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INTEGRA Bespoke Lighting
12-11-2007, 07:28 AM
Ok Everyone.... Lets see them....

I would like to build a compendium of VOLTAGE DROP FORMULAS.

So, get out your handy slide rule, or look up the info in your favourite manufactueres tech manuals, or call your local cable rep, and lets post up as many different Voltage Drop Formulas as we can find.

No Bickering, lets keep it clean!

Then once we have a few different versions here, I will purchase a brand new, calibrated, TRUE RMS Meter from either Fluke or Greenlee and set about to test each method, reporting back my findings.

This should be fun!

Chris J
12-11-2007, 07:37 AM
I just use the simple formula to get me very close. I always use the meter for final calculations and settings.
Length x watts divided by cable constant, then multiply by 2.
This generally puts me right where I need to be, but the meter has the final say.

INTEGRA Bespoke Lighting
12-11-2007, 07:52 AM
Ahh I should have been more specific here! Can you please also include the "Cable Constant" figure you are using. Lets keep things simple and go with 12/2 as our base line cable.

Thanks.

pete scalia
12-11-2007, 08:11 AM
If you must rely upon referencing a mathematical formula every time you build a low voltage lighting circuit then you'd better find another line of work cause you'll never make it in this business. If you have experience and a voltage and amperage meter then you will never ever need to even know any voltage drop formulas.

irrig8r
12-11-2007, 09:34 AM
Pete, please explain to me how you plan a job on paper with your multimeter. It simply ain't gonna happen my friend.

Pro-Scapes
12-11-2007, 09:40 AM
its rare i find myself determining voltage drop before a job. I can usually come REAL close by adding up the run what tap I need to be on then without a formula I check a lamp underload for the proper voltage and adjust if needed. Often times I find wire runs need to be routed another route or otherwise changed in lenght. There is no one formula that will compensate for real world testing and adjustment of each and every system

Its also a rarity I need a tap over 14v too. I think I recall 1 time needed a trans that would go over 15v and that was on a retro/reinstall where client declined all new

If I need to determine vd before a job I use chris's method

As for planning on paper we use a sketch or site plans... determine wattages and ALWAYS assume more will be added. Additional lights are an easy upsell if they do not need to purchase a new trans. I do run calculations but I have no practice of determining VD before a Job. The cast wire calculator or unique wizard will do all of this for you

JoeyD
12-11-2007, 09:55 AM
AMPS x DISTANCE x 2 x .00162 (12/2 RESISTANCE)

No need to run a test, I am telling you that this is the best and most accurate VD method. Trust me when I say we have run all the tests you plan to run and this method always is most accurate. Like Pete said a Volt Meter is the absolute best way to calculate and then to echo Billy, my Wireng Wizard does all of the thinking for you.

But have at it, MAKE SURE YOU POST YOUR METHOD OF CHOICE JAMES!!!!! and let us know the criteria becuase for fun I will run the same tests. So what is our citeria

200ft 12/2 run w/ 100watts? testing to the first point of connection?? Hub wireing or Daisy Chain, or T?

irrig8r
12-11-2007, 09:57 AM
James,
Nate Mullen's formula doesn't use a cable constant... as I showed in my example the other day, it's like this:

(Distance x 2) x Amperage x Resistance

At first I thought that they might have a vested interest in raising voltage drop numbers to justify their multi-tap system.

Then I checked it with the formula Vista uses. It is the same as Nightscaping's formula except that the wire length is multiplied by 2 (by some notion that the electricity is flowing both directions on the wire) and it gets results similar to but not quite as high as the Unique formula..


(Distance x 2) x VA/ cable constant

(using the same cable constants as the NS formula)

I've tested Vista's formula against my meter readings, and it comes the closest and is good enough to plan jobs with.

BTW, I was talking with the Vista rep yesterday at my distributor about it. He said they sell multi-tap systems that go up to 22 V too (probably just to maintain market share) but he'd never run into a job where more than 15 V was needed.

He said that in the long run the client pays more for wasted electricity and that as the cost of power goes up (who on earth thinks it won't?) it will outweigh the initial materials savings.

On the other hand, we both agreed that LEDs will change everything.

JoeyD
12-11-2007, 10:05 AM
James,
Nate Mullen's formula doesn't use a cable constant... as I showed in my example the other day, it's like this:

(Distance x 2) x Amperage x Resistance

At first I thought that they might have a vested interest in raising voltage drop numbers to justify their multi-tap system.

Then I checked it with the formula Vista uses. It is the same as Nightscaping's formula except that the wire length is multiplied by 2 (by some notion that the electricity is flowing both directions on the wire) and it gets results similar to but not quite as high as the Unique formula..


(Distance x 2) x VA/ cable constant

(using the same cable constants as the NS formula)

I've tested Vista's formula against my meter readings, and it comes the closest and is good enough to plan jobs with.

BTW, I was talking with the Vista rep yesterday at my distributor about it. He said they sell multi-tap systems that go up to 22 V too (probably just to maintain market share) but he'd never run into a job where more than 15 V was needed.

He said that in the long run the client pays more for wasted electricity and that as the cost of power goes up (who on earth thinks it won't?) it will outweigh the initial materials savings.

On the other hand, we both agreed that LEDs will change everything.

Your Vista rep needs to do a bit more research. why would having taps 16-22v cause wasted electricity.makes no sense?

And yeah Vista makes a TF that is NON UL 1838 it is listed UL 506 and goes to 22v to COMPETE WITH UNIQUE!! obviously.

We did not manipulate the formula to increase VD, unlike what most think we are not slimeballs looking to make an extra buck. Anyone who comes to our classes for the last 10 years knows we lead the industry in education and we always inform people based off of FACT and we prove this with volt meters and amp probes. And no we do not calibrate our own meters.

unbelieveable. Never been on a job that needed more than 15V HAHAHAHAHAH

Must not of ever pulled a 12/2 run more than 200 ft with 80 watts on it???? Sounds like the rep has never been on a big job. Oh wait let me guess, he uses 10/2 for those long runs.......sounds real cost effective.

Lite4
12-11-2007, 10:07 AM
"Vd" voltage drop = "A" Amps in wire x "R" Resistance in wire x "L" Length of the cable to the hub x 2

Resistance for 12/2 wire = .00162

Always verify with Voltmeter

Lite4
12-11-2007, 10:09 AM
You know I have always wondered about different manufacturers wire as well. Testing the same length and guage of wire of 3 or 4 different manufacturers and see if all the wire is fairly even.

klkanders
12-11-2007, 11:24 AM
Can I just say I love saying the word "Compendium". I love reading these posts late at night, they are great, but they sometimes make me soporific. :)

INTEGRA Bespoke Lighting
12-11-2007, 01:03 PM
Reading never ending arguments can tend to make one soporific I find...

Ok so we have the Nightscaping Formula, and we have the Unique Formula, and we have the Vista Formula...

Are there any other, different Voltage Drop formulas out there that people know of? Not much of a compendium unless we find more then three....

Lets not break down into bickering about who does what to whom, where and when here... That doesnt enter into the scientific method as I recall. This isnt about exposing those who do VD analysis during planning or build out VS. those that use meters at the end of the job to balance Multi-Tap Transformers. This is simply to do some exploring and testing of method and accuracy.

INTEGRA Bespoke Lighting
12-11-2007, 01:20 PM
There has been some talk here that the Nightscaping Voltage Drop Formula is inaccurate and that it only applies to DC circuits. It has been suggested that when using this formula on AC circuits that the cable distance needs to be multiplied by two.

The people who suggest this state that the multiplication x 2 needs to be done because in an AC circuit the electricity must run the length of the wire and then back again.

As far as I understand it (that phrase is for you Pete), This is backwards thinking. In an AC circuit the electricity is "flowing" back and forth at 60hz, thus setting up a 'wave' of energy through the circuit. It is in a DC circuit that the electricity travels from one pole down the length of one side of the cable, through the load, and back down the other side of the cable to the other pole. (thuse twice the distance) This, as I understand it, (again for you Pete) is the inherent inefficiency of large or long DC circuits and thus one of the main reasons our electricity distribution system is an AC system

I stand to be corrected, but please, if I am wrong about this, take the time to fully and completely explain your rationale. Perhaps one of our electrical contractor friends might be able to chime in here. Could just set us all straight.

Thanks.

steveparrott
12-11-2007, 01:58 PM
CAST uses the same formula as Unique - the most accurate that I know of.

The Nightscaping formula seems to be off because they don't have the 2X multiplier.

As far as calculators go, the system calculator on the CAST website is the most accurate and full-featured. It warns you when commons are overloaded and when wire ratings are exceeded. It also calculates energy cost.

JoeyD
12-11-2007, 02:15 PM
The CAST wire calculator is very nice I must admit!

I came by your booth (IA) Steve to say hello but you were not there. Just wanted to put a face to the name.

Maybe next time!!

steveparrott
12-11-2007, 02:25 PM
Thanks Joey, sorry I missed you!

johnh
12-11-2007, 04:38 PM
Are there any other, different Voltage Drop formulas out there that people know of? Not much of a compendium unless we find more then three....



AC Circuits

For AC circuits, where AC resistance and inductive reactance are considered, the following is the IEEE Std 141 exact voltage drop formula.



where:
Vd = Voltage drop (Line to Neutral)
V = Voltage (source)
I = Current in amperes (A)
R = AC Resistance from NEC® Chapter 9 Table 9 (Ohms to Neutral)
X = AC Reactance from NEC® Chapter 9 Table 9 (Ohms to Neutral)
distance (L) is considered from the Resistance & Reactance Tables
where Ohms per unit / 1000 * L in same unit = R or X
θ = Angle of Phase Offset = Arc Cosine (device or circuit Power Factor)
Line to Line is computed by Line to Neutral VD / Sqrt(3).


DC Circuits



where:
Vd = Voltage drop
R = DC Resistance from NEC® Chapter 9 Table 8
L = Distance
I = Current in amperes (A)

K = Material Resistivity constant - 12.9 for Cu & 21.2 for Al
CM = Circular mils of conductor

These are the IEEE formulae if you've got a good calculator and a dictionary!
JH

INTEGRA Bespoke Lighting
12-11-2007, 04:53 PM
Oh gee thanks John! Now I have to ge get my electrical engineering degree to decipher all of that.

I dont suppose you would like to work that out into a working formula and then put it through a test for us would you?

Chris J
12-11-2007, 07:00 PM
Can I just say I love saying the word "Compendium". I love reading these posts late at night, they are great, but they sometimes make me soporific. :)

:laugh::laugh::laugh: Stop it! I think I just pissed on myself! :laugh::laugh::laugh:

Chris J
12-11-2007, 07:03 PM
Ok so we have the Nightscaping Formula, and we have the Unique Formula, and we have the Vista Formula...

Are there any other, different Voltage Drop formulas out there that people know of? Not much of a compendium unless we find more then three....

.

What am I, chopped meat? What about the Johnson Lighting formula!?

Chris J
12-11-2007, 07:09 PM
AC Circuits

For AC circuits, where AC resistance and inductive reactance are considered, the following is the IEEE Std 141 exact voltage drop formula.



where:
Vd = Voltage drop (Line to Neutral)
V = Voltage (source)
I = Current in amperes (A)
R = AC Resistance from NEC® Chapter 9 Table 9 (Ohms to Neutral)
X = AC Reactance from NEC® Chapter 9 Table 9 (Ohms to Neutral)
distance (L) is considered from the Resistance & Reactance Tables
where Ohms per unit / 1000 * L in same unit = R or X
θ = Angle of Phase Offset = Arc Cosine (device or circuit Power Factor)
Line to Line is computed by Line to Neutral VD / Sqrt(3).


DC Circuits



where:
Vd = Voltage drop
R = DC Resistance from NEC® Chapter 9 Table 8
L = Distance
I = Current in amperes (A)

K = Material Resistivity constant - 12.9 for Cu & 21.2 for Al
CM = Circular mils of conductor

These are the IEEE formulae if you've got a good calculator and a dictionary!
JH

Just tell us the web site you cut and paste it from and we can figure out the rest.

klkanders
12-11-2007, 07:46 PM
:laugh::laugh::laugh: Stop it! I think I just pissed on myself! :laugh::laugh::laugh:

I am quite proud of myself......soporific was the Webster word of the day.
Compendium is so yesterday. Glad you enjoyed it Chris! :laugh:

Chris J
12-11-2007, 08:04 PM
I come more from the "Jeff Foxworthy" dictionary. These big $10 words just confuse us rednecks. See ya later, gotta go catch a gater in my pond!

irrig8r
12-11-2007, 08:07 PM
Your Vista rep needs to do a bit more research. why would having taps 16-22v cause wasted electricity.makes no sense?

Nate talked about the energy wasted in his book Joey. He justifies that cost of running the system by the savings in the initial materials outlay.

Electricity runs me $0.11 / KWH currently. If I doubled my use it would cost me a $0.23/ KWH. Large residential users pay more. One customer where I'm planning a job is already paying $400/ mo. for electric and gas. i don't expect power to be less expensive in the future, do you?

And yeah Vista makes a TF that is NON UL 1838 it is listed UL 506 and goes to 22v to COMPETE WITH UNIQUE!! obviously.

Yep, as I said in another post they play both sides of the 1838 fence. Just goes to show you the impact Unique is having in the marketplace.

We did not manipulate the formula to increase VD, unlike what most think we are not slimeballs looking to make an extra buck. Anyone who comes to our classes for the last 10 years knows we lead the industry in education and we always inform people based off of FACT and we prove this with volt meters and amp probes. And no we do not calibrate our own meters.

You're a class act Joey.You know I respect you and Nate. I didn't accuse you of any funny business. I admit to having once had a bias against your company, reinforced by what I was hearing from some of your competitors...

I'm more open-minded now. But even they weren't calling you slimeballs.

unbelieveable. Never been on a job that needed more than 15V HAHAHAHAHAH

Must not of ever pulled a 12/2 run more than 200 ft with 80 watts on it???? Sounds like the rep has never been on a big job. Oh wait let me guess, he uses 10/2 for those long runs.......sounds real cost effective.


Well most of the jobs I encounter have (for instance) power available at each end of the driveway, for gates and post lights at the far end, and in or near the garage at the other. Most of those aren't longer than 200 ft., so a 100 ft. run isn't unreasonable to work with up to 15 v.

Chris J
12-11-2007, 08:44 PM
I agree that the 22v trans is not normally necessary with my installs, but sometimes a 16v tap would come in real handy. My position is that if I needed a 22v tap, the lights are WAY too far from the tranny, thus causing me to bring in the electrician for an extra power source. There have been situations in the past that have provoked me to use the higher volt transformers, however, and this is why I will always promote their existence. There is absolutely no reason why 22v should scare anyone who knows what they are doing (UL 1838 listing or not). In my opinion, this is what seperates the men from the boys. You either know how to handle your tools or you don't......simple as that.

irrig8r
12-11-2007, 09:30 PM
Except for the ones that don't really know how to handle them but try anyway.... I don't mean anyone here of course, but I've had to correct a lot of stupid install mistakes made by other folks out there.

irrig8r
12-11-2007, 09:48 PM
(continuing because I let this sit for longer than 10 minutes)

This past year that's included 3 jobs w/ multi-tap transformers where the first fixture on the run had 14 V and the customer wondered why her lights kept burning out so quickly... One had the lower voltage to the more distant fixtures and the higher voltage to the closer ones... Another had two cables installed so the hot and common went to different circuits (still ran though).

As much as distributors and manufacturers try to pass along how things are supposed to be put together, even offering various free basic workshops and seminars, there are still a lot of dummies out there that do things wrong because they either don't know any better or don't care.

When they go out of business, they leave a wake of unhappy customers who end up paying twice for a job. These are the ones I worry about doing something stupid like causing a fire and giving the industry a bad name. Not that I'm losing any sleep over it, but just saying....

klkanders
12-11-2007, 10:09 PM
Hey Gregg, It makes you wonder thats for sure. Spending more money on the bigger trans. that they usually do not need. I for the most part use the 15v tap max but on a few occasions had one longer run w more fixtures that I used 10g on to do it right. Can it be they are taught wrong or just forget everything when they walk out the door? The problems you mentioned should not happen even with a 2 hour class if the individual has half a brain and a meter? Guess your the lucky one that gets to fix them! Take Care!

Chris J
12-11-2007, 10:12 PM
Greg,
I am right there with you on this one! There are far too many people installing lighting than there should be. This is the main reason why I tell my customers that I am the ONLY lighting contractor in Jacksonville, Florida who holds a state license for both Florida and Georgia. No other contractor in my region can make this claim! I have spent many years, and tens of thousands of dollars toward learning my craft. There is no other person in my market that I could honestly call a true competitor, however, there will always be the thrifty homeowner looking for the cheaper way out. They, too, will ultimately become my customer when their "so-called" contractor abandons them.

pete scalia
12-11-2007, 10:23 PM
Pete, please explain to me how you plan a job on paper with your multimeter. It simply ain't gonna happen my friend.

Plan a job on paper? why do you need to do that. I determine all my cable and fixture configurations in the field.

Chris J
12-11-2007, 10:39 PM
There has been some discussion on installation time, and I think this is one of those time consuming areas where others might have missed the boat.
I do all of my preliminary calculations on paper before I arrive at the job site. I know which lights are going to which runs. I know which runs are going to each voltage tap.
I thought everyone did this, but I was obviously wrong. I can tell you this though, I still install 20 light systems in 3-4 hours and this is probably one of the main reasons why we can do it so efficiently.

Lite4
12-11-2007, 11:29 PM
I thought everyone did this, but I was obviously wrong. I can tell you this though, I still install 20 light systems in 3-4 hours and this is probably one of the main reasons why we can do it so efficiently.


Man Chris, 3-4 hours for an install. That is usually how long it takes me to set up a demo by myself with the wires above ground. That is smokin fast brother. I want to dig in the sand too.

pete scalia
12-11-2007, 11:32 PM
Man Chris, 3-4 hours for an install. That is usually how long it takes me to set up a demo by myself with the wires above ground. That is smokin fast brother. I want to dig in the sand too.

Tim, me and you should take a trip down this winter and study under the master Johnson. In fact he should be hosting Aolp. He's the finest around.

Lite4
12-11-2007, 11:40 PM
No doubt. He obviously has things dialed in a lot better than I do. Cudos to you Chris.

johnh
12-11-2007, 11:47 PM
I dont suppose you would like to work that out into a working formula and then put it through a test for us would you?

Sorry James, thought the formulas were there when cut and pasted that in. Here they are;

http://www.flickr.com/photos/thehigos/2105078126/
http://www.flickr.com/photos/thehigos/2105078148/

I didn't bother with the DC calculation, but for the AC at 100W and 100ft, i calculated it to be 1.68. Perhaps someone could verify that?

There also seems to be a lot of discussion around multi-tap and voltages up to 22V. My $.02...the reason UL1838 limits to 15V is a matter of safety, and not for the experienced contractors on here, but the uneducated and unaware homeowner, the kids playing in the yard, the unsuspecting gardener. 15V is the maximum safe voltage for let go current.
JH

INTEGRA Bespoke Lighting
12-12-2007, 12:34 AM
(continuing because I let this sit for longer than 10 minutes)

This past year that's included 3 jobs w/ multi-tap transformers where the first fixture on the run had 14 V and the customer wondered why her lights kept burning out so quickly... One had the lower voltage to the more distant fixtures and the higher voltage to the closer ones... Another had two cables installed so the hot and common went to different circuits (still ran though).

As much as distributors and manufacturers try to pass along how things are supposed to be put together, even offering various free basic workshops and seminars, there are still a lot of dummies out there that do things wrong because they either don't know any better or don't care.

When they go out of business, they leave a wake of unhappy customers who end up paying twice for a job. These are the ones I worry about doing something stupid like causing a fire and giving the industry a bad name. Not that I'm losing any sleep over it, but just saying....

Gregg, you speak the truth.

There is a certain level of responsibility we all should have in installing our systems. Lets face it, even the best contractor in the world will not maintain 100% client loyalty, or properties get sold, etc etc. Why bother installing equipment that could be an issue in the future, making the whole system and the LV lighting biz in general look bad. (" I have a LV system and it has never worked right, the lights keep burning out" or whatever)

The number of times I have needed more the 15v on a tap to accomplish an install is so rare as to not be an issue. I am lucky, most of my larger jobs are new construction and I have the opportunity to spec. in a complete electrical system as required. I can see the occasional need for up to 22v, but the possible trouble and misunderstanding that it can cause in the future (caretakers, irrigators, electricians... who all think it is a 12v not a LV system) is not worth it to me.

Well, that is my .02 for tonight.

irrig8r
12-12-2007, 01:30 AM
Greg,
I am right there with you on this one! There are far too many people installing lighting than there should be. This is the main reason why I tell my customers that I am the ONLY lighting contractor in Jacksonville, Florida who holds a state license for both Florida and Georgia. No other contractor in my region can make this claim! I have spent many years, and tens of thousands of dollars toward learning my craft. There is no other person in my market that I could honestly call a true competitor, however, there will always be the thrifty homeowner looking for the cheaper way out. They, too, will ultimately become my customer when their "so-called" contractor abandons them.

(Chris, when you mention all that I get a better understanding of why you were a little bent out of shape when I was advising Matt the other day about his home system.)

irrig8r
12-12-2007, 01:34 AM
Sorry James, thought the formulas were there when cut and pasted that in. Here they are;

http://www.flickr.com/photos/thehigos/2105078126/
http://www.flickr.com/photos/thehigos/2105078148/

I didn't bother with the DC calculation, but for the AC at 100W and 100ft, i calculated it to be 1.68. Perhaps someone could verify that?

There also seems to be a lot of discussion around multi-tap and voltages up to 22V. My $.02...the reason UL1838 limits to 15V is a matter of safety, and not for the experienced contractors on here, but the uneducated and unaware homeowner, the kids playing in the yard, the unsuspecting gardener. 15V is the maximum safe voltage for let go current.
JH

Maybe I need computer glasses, but I don't see any formulas John. AHHH....I do see two flickr.com links right now as I type this in my reply, but they didn't show up in your post. Weird.

INTEGRA Bespoke Lighting
12-12-2007, 01:52 AM
Sorry James, thought the formulas were there when cut and pasted that in. Here they are;

http://www.flickr.com/photos/thehigos/2105078126/
http://www.flickr.com/photos/thehigos/2105078148/

I didn't bother with the DC calculation, but for the AC at 100W and 100ft, i calculated it to be 1.68. Perhaps someone could verify that?

There also seems to be a lot of discussion around multi-tap and voltages up to 22V. My $.02...the reason UL1838 limits to 15V is a matter of safety, and not for the experienced contractors on here, but the uneducated and unaware homeowner, the kids playing in the yard, the unsuspecting gardener. 15V is the maximum safe voltage for let go current.
JH

Sorry John, the links did not show up in your post for some reason.

johnh
12-12-2007, 08:48 AM
Sorry John, the links did not show up in your post for some reason.
Wierd, showed up on my computer at home, but not here. Anyway, here is the link to the website;
http://www.dolphins-software.com/IEEE_ExactFormulae.htm
I used .95 as the powerfactor. I can also attach the NEC table if anyone needs it.
JH

JoeyD
12-12-2007, 09:16 AM
Your Vista rep needs to do a bit more research. why would having taps 16-22v cause wasted electricity.makes no sense?

Nate talked about the energy wasted in his book Joey. He justifies that cost of running the system by the savings in the initial materials outlay.

Electricity runs me $0.11 / KWH currently. If I doubled my use it would cost me a $0.23/ KWH. Large residential users pay more. One customer where I'm planning a job is already paying $400/ mo. for electric and gas. i don't expect power to be less expensive in the future, do you?

And yeah Vista makes a TF that is NON UL 1838 it is listed UL 506 and goes to 22v to COMPETE WITH UNIQUE!! obviously.



Yep, as I said in another post they play both sides of the 1838 fence. Just goes to show you the impact Unique is having in the marketplace.

We did not manipulate the formula to increase VD, unlike what most think we are not slimeballs looking to make an extra buck. Anyone who comes to our classes for the last 10 years knows we lead the industry in education and we always inform people based off of FACT and we prove this with volt meters and amp probes. And no we do not calibrate our own meters.

You're a class act Joey.You know I respect you and Nate. I didn't accuse you of any funny business. I admit to having once had a bias against your company, reinforced by what I was hearing from some of your competitors...

I'm more open-minded now. But even they weren't calling you slimeballs.

unbelieveable. Never been on a job that needed more than 15V HAHAHAHAHAH

Must not of ever pulled a 12/2 run more than 200 ft with 80 watts on it???? Sounds like the rep has never been on a big job. Oh wait let me guess, he uses 10/2 for those long runs.......sounds real cost effective.


Well most of the jobs I encounter have (for instance) power available at each end of the driveway, for gates and post lights at the far end, and in or near the garage at the other. Most of those aren't longer than 200 ft., so a 100 ft. run isn't unreasonable to work with up to 15 v.

Sorry Gregg, I had a long couple of days. I knew you werent calling us slimeballs, sometimes I can think I can read intot he mind of these other reps.

At any rate, I appreciate you giving us a shot. I may have mis understood what you were meaning by wasted electricity. My thinking was that they were stating why have extra taps that waste extra energy. You dont always use a higher tap but there are times that you may need it. Our competiton will tell you to use bigger cable or put your transformer out further in the yard. We simply tell you to pull the run and distribute the voltage. 200ft runs are not uncommon when using our products, they are more uncommon when you limit your TF to 15v. You find ways to not pull 200ft. But when you have the ability why not?

Joey D.

JoeyD
12-12-2007, 09:19 AM
Sorry James, thought the formulas were there when cut and pasted that in. Here they are;

http://www.flickr.com/photos/thehigos/2105078126/
http://www.flickr.com/photos/thehigos/2105078148/

I didn't bother with the DC calculation, but for the AC at 100W and 100ft, i calculated it to be 1.68. Perhaps someone could verify that?

There also seems to be a lot of discussion around multi-tap and voltages up to 22V. My $.02...the reason UL1838 limits to 15V is a matter of safety, and not for the experienced contractors on here, but the uneducated and unaware homeowner, the kids playing in the yard, the unsuspecting gardener. 15V is the maximum safe voltage for let go current.
JH

NEC CLEARLY STATES 30V OR LESS IS SAFE!

JoeyD
12-12-2007, 09:34 AM
When is the test being done James?? I am ready to go here buddy!!

johnh
12-12-2007, 09:45 AM
NEC CLEARLY STATES 30V OR LESS IS SAFE!

Hi Joey, I didn't just make this up. This is an excerpt from the IAEI magazine, Nov/Dec 2004 issue.
"A non-sinusoidal peak voltage of 42.4 volts for an ac circuit is considered a safe voltage under dry conditions and would not normally constitute a shock or fire hazard. In wet conditions, this voltage must be limited to 15 volts for a sinusoidal ac and 21.2 volts peak for a non-sinusoidal ac. Since the body’s resistance is decreased by water, the permissible voltage of the output of the low-voltage system is decreased accordingly to ensure safe handling and operation of these circuits where water is a concern. Using low-voltage systems in close proximity to or in fountains and swimming pools should only be considered when all the NEC requirements are applied"
Link to full document here http://www.iaei.org/subscriber/magazine/04_f/ode.htm
The outdoor landscape is generally considered to be wet conditions, although this may not be the case in some desert climes.
This is substantiated by the IEC Technical Specification 60479-1 on touch voltages.
30V is the maximum safe voltage for ventricular fibrulation. 15V is the maximum safe voltage for painful "Let-Go" current. By limiting to 15V, UL1838 has eliminated 15V of pain!
JH

JoeyD
12-12-2007, 10:46 AM
Hi Joey, I didn't just make this up. This is an excerpt from the IAEI magazine, Nov/Dec 2004 issue.
"A non-sinusoidal peak voltage of 42.4 volts for an ac circuit is considered a safe voltage under dry conditions and would not normally constitute a shock or fire hazard. In wet conditions, this voltage must be limited to 15 volts for a sinusoidal ac and 21.2 volts peak for a non-sinusoidal ac. Since the body’s resistance is decreased by water, the permissible voltage of the output of the low-voltage system is decreased accordingly to ensure safe handling and operation of these circuits where water is a concern. Using low-voltage systems in close proximity to or in fountains and swimming pools should only be considered when all the NEC requirements are applied"
Link to full document here http://www.iaei.org/subscriber/magazine/04_f/ode.htm
The outdoor landscape is generally considered to be wet conditions, although this may not be the case in some desert climes.
This is substantiated by the IEC Technical Specification 60479-1 on touch voltages.
30V is the maximum safe voltage for ventricular fibrulation. 15V is the maximum safe voltage for painful "Let-Go" current. By limiting to 15V, UL1838 has eliminated 15V of pain!
JH

This is great!!

Thanks John. I have so much I want to say but I am going to keep my mouth shut and let the authority for our company on this subject speak. This is nothing new by the way. We have been doing this for quite a while now and have read and heard all of the arguments pertaining to UL 1838. The UL guy at AOLP last year regergatated the same stuff and it is fact driven but Nate quickly had the guy back peddling when he began questioning him. But mind you UL1838 is not the only code listed for powering up low voltage lighting in wet or dry locations. Call us what you will but you cannot find one job that we have been flagged on or dismissed on and there are reasons....more to come...I do love this though!!!

Along with the whole article I did find this part quite interesting and apply's to this subject we are on here.......

"If larger wire is necessary to counter voltage drop in long runs, Type UF (Underground Feeder and Branch circuit) cable could be used. Another method would be to start a long run with 12 AWG SPT-3 cable and then convert to 16 AWG or 14 AWG in the middle or toward the end of the run. Limiting the number and size of lamps on the long run will also provide a solution for excessive voltage drop. The following formula will help determine the voltage drop in your circuit: 2 X length of run X ampacity of load X the resistance of the wire in thousand feet (that value can be found in Table 8 of chapter 9 using the uncoated wire column) divided by 1000 feet = voltage drop."


Looks like someone else believes in our VD method...That again we did not create, we only pulled from electrical engineering books.

Nice work John!!

INTEGRA Bespoke Lighting
12-12-2007, 11:26 AM
I'm thinking a better challenge would be John H up against Joey in an arm wrestle! Knowing John, I would put my money on him!

John, keep all the technical research and quotes you have amassed over all these years coming.... I don't have the time or the opportunity to pour through all this stuff and you certainly have a ton of experience and knowledge in this area. I for one really appreciate the input and the greater understanding of the technical issues that you are bringing to this group.

Have a great day.

JoeyD
12-12-2007, 08:46 PM
OK back to the topic at hand. This afternoon I ran the test. I also videotaped my findings. I hope to post it tommorow. I tested 3 different VD methods. I hope to have the video loaded and posted by tommowor afternoon. James, you should still run your own and let us know what your findings are.

Lite4
12-12-2007, 09:39 PM
This is great info guys, can't wait to see the results.

INTEGRA Bespoke Lighting
12-12-2007, 09:44 PM
OK back to the topic at hand. This afternoon I ran the test. I also videotaped my findings. I hope to post it tommorow. I tested 3 different VD methods. I hope to have the video loaded and posted by tommowor afternoon. James, you should still run your own and let us know what your findings are.

Joey, you are WAYYYYY ahead of me man! I spent the better part of today taking apart the various UL and CSA standards to see how they tick, then I rigged up a nice parallel trickle charge system for all my boat batteries that are stored for the winter...

I was thinking about getting around to these Voltage Drop Tests sometime in January to be honest... A guy has to ease into the winter 'experimentation season' if you know what I mean.

:)

JoeyD
12-12-2007, 10:41 PM
James you should know how we Unique guys roll. We start work at 6 am and going until 10-11pm is not uncommon. Dont get me wrong this isnt an academy award winning film, this is a real basic thing that I did by myself with a video camera. But it works.

Joey D.

PatriotLandscape
12-13-2007, 12:53 PM
for my systems I have used the cast ligthing system calculator. I have only installed one system but have used it for proposals.

JoeyD
12-13-2007, 01:14 PM
We have the Unique wiring wizard which does the same thign but also allows you to print detailed reports for all your transformers and hubs. It is a really cool program that is going through revisions to make it even better. It soon will be it;s own web page so we can constantly update it. You can request one for me to mail out or you can download it from http://www.uniquelighting.com/product_pages/Wiring_Wizard.htm

Joey D.

JoeyD
12-13-2007, 06:30 PM
Ok boys so after reviewing my video I can tell you the results are very very interesting. I think you ugys will be surprise to see the method that actually comes out closest. After reviewing I decided that I could use it for so much more than just for us here on Lawnsite. So I reshot it this afternoon with my Creative Director and we are going to use some graphics to better explain. I origionally shot it with my hand held camera and used a white board for the graphics. It worked but me being a darn perfectionist had to go on and re film it. I will post within a few days as my guy just has to edit and put in some porno music in the background........bow-chika-bow-wow

klkanders
12-13-2007, 06:56 PM
Oh My! Is it titled " Joey does Voltage Drop"
I hope this has a G rating.
Sorry for this but you made me do it Joey!

JoeyD
12-13-2007, 07:36 PM
LOL......Dont worry you will not see any bare flesh. I want you guys to be able to learn like I did here and not throw up!! When I did it myself it was good enough but my creative director saw it and about freaked out. "Why did you do this without me!?" I can make this much better......waaa waaa waaa..." So I let the guy re do it so he could sleep at night. He's my good buddy so I guess I will just have to put my homemade video away.

steveparrott
12-14-2007, 12:58 PM
Hi Joey, I didn't just make this up. This is an excerpt from the IAEI magazine, Nov/Dec 2004 issue.
"A non-sinusoidal peak voltage of 42.4 volts for an ac circuit is considered a safe voltage under dry conditions and would not normally constitute a shock or fire hazard. In wet conditions, this voltage must be limited to 15 volts for a sinusoidal ac and 21.2 volts peak for a non-sinusoidal ac. Since the body’s resistance is decreased by water, the permissible voltage of the output of the low-voltage system is decreased accordingly to ensure safe handling and operation of these circuits where water is a concern. Using low-voltage systems in close proximity to or in fountains and swimming pools should only be considered when all the NEC requirements are applied"
Link to full document here http://www.iaei.org/subscriber/magazine/04_f/ode.htm
The outdoor landscape is generally considered to be wet conditions, although this may not be the case in some desert climes.
This is substantiated by the IEC Technical Specification 60479-1 on touch voltages.
30V is the maximum safe voltage for ventricular fibrulation. 15V is the maximum safe voltage for painful "Let-Go" current. By limiting to 15V, UL1838 has eliminated 15V of pain!
JH

John,

Your assessment of the IEC TS 60479-1 is correct on the assertion that 30V is the maximum safe voltage for ventricular fibrulation (assuming a bodly resistance of 1000 ohms). Note that this corresponds to large surface area contact between two sweaty hands. In practice, the scenario would need to be something like grasping an energized wrench firmly in each hand. How that would ever happen during an installation is a mystery to me.

Much more likely (as a worst case scenario) would be holding (with sweaty hands) onto an energized screwdriver shank and a live bare wire. The bodily resistance of such a contact would be about 9 times the above - resulting in a current exposure of about 2 mA (at 22 volts) that would deliver a shock but nowhere near the let-go threshold.

Let's not forget that there has never been a serious injury reported from contact with any circuit under 30 volts. In fact, in a 12-year study from OSHA, there were zero deaths reported from contact with any volltage under 110 volts.

The 1838 voltage limitation of 15 volts has no authentic scientific basis.

steveparrott
12-14-2007, 01:18 PM
A further note - the reason I'm taking the time to dispute any claims that lv lighting is dangerous is because I'm working hard to change state laws that restrict lv lighting to licensed electricians. We're introducing legislation that will exempt lv lighting in NJ and will move onto to other states. Half of our 50 states require some form of licensing and there is movement in other states to adopt new licensing.

Let's all of us, the landscape lighting professionals, deliver clear and indisputable assertions that lv lighting is 100% safe from harmful electric shock. Electricians across the country would love to make people believe otherwise.

JoeyD
12-14-2007, 01:22 PM
Very well put Steve. We are all in this togeather and all this talk of anything non UL 1838 being dangerous and a hazard is just proposterous and simply is not true.

pete scalia
12-14-2007, 08:46 PM
I will tell you that I've gotten some very real shocks from 12 volt lighting. Try touching a conductor to an open cut on your hand. Try holding two conductors loosely between your thumb and forefinger and you will singe your skin. Also with twelve volts it's not so much the shock risk but the risk of fire due to overheated conditions during shorting and overloads. It's the high amperage that'll get ya there. Better safe than sorry.

Pro-Scapes
12-15-2007, 07:26 AM
I agree with ya pete. It was damp out when I was working one time and I got a little zap. I guess thats what you get for not shutting the power off.

I got burned one time pretty bad when I was younger from a 7.2v RC battery at high amperages. Anything high amperage and bad connections is dangerous. There should be more regulation on LV lighting but you shouldnt need to be a full electrician for it. Respect the electricity and it will do what its supposed to do.

NightScenes
12-15-2007, 11:07 AM
I agree with ya pete. It was damp out when I was working one time and I got a little zap. I guess thats what you get for not shutting the power off.

I got burned one time pretty bad when I was younger from a 7.2v RC battery at high amperages. Anything high amperage and bad connections is dangerous. There should be more regulation on LV lighting but you shouldnt need to be a full electrician for it. Respect the electricity and it will do what its supposed to do.

Billy, you can't compare ac and dc voltage like this, dc voltage is much more severe and we do not work with it.

As for arching, you can put 16 amps on 12/2 wire with 12 volts, 15 volts, or 22 volts, it really doesn't make a difference. Amps are amps no matter the voltage. So that's not a good argument either. You can create just as much arch from a 10 volt system on smaller wire as you can on a 24 volt system. It's just a matter of knowing the rules and how to apply them.

The facts are, no one has ever been injured by 30 volts or less. This is why the NEC has placed this limitation in the code (411).

pete scalia
12-15-2007, 07:25 PM
I agree with ya pete. It was damp out when I was working one time and I got a little zap. I guess thats what you get for not shutting the power off.

I got burned one time pretty bad when I was younger from a 7.2v RC battery at high amperages. Anything high amperage and bad connections is dangerous. There should be more regulation on LV lighting but you shouldnt need to be a full electrician for it. Respect the electricity and it will do what its supposed to do.

Excellent post Billy. That statement that nobody has ever been hurt from 30 volts or less is absolutely ludicrous and unfounded. I can't believe that some people would be so unscrupulous to suit their own agenda to perpetuate a statement like that. I would bet that even the slightest shock to someone with a pacemaker or a weak heart could be potentially fatal.
I'm sorry but it's not worth potentially harming someone over a landscape light system operating at higher than 15 volts.

ChampionLS
12-16-2007, 03:20 AM
It's not the voltage thats dangerous, it's the amperage at a specific voltage that can harm you. Low voltage lighting is regulated not to exceed 15 Volts at 25 amps as per UL1838. This is where they set the cap as a safety regulation. No secondary circuit should exceed 300 watts, because that equals 25 amps. The golden rule is 25 amps or 300 watts at whichever voltage you decide 12-15.

Can you be electrocuted from 300 watts/25 amps... most likely not, but you can definitely count on feeling the current from it. There is more of a burn hazard from short circuiting of wires then any type of voltage arch. It's best to have the power supply turned off when splicing, or if your hands are wet.

pete scalia
12-16-2007, 09:20 AM
It's not the voltage thats dangerous, it's the amperage at a specific voltage that can harm you. Low voltage lighting is regulated not to exceed 15 Volts at 25 amps as per UL1838. This is where they set the cap as a safety regulation. No secondary circuit should exceed 300 watts, because that equals 25 amps. The golden rule is 25 amps or 300 watts at whichever voltage you decide 12-15.

Can you be electrocuted from 300 watts/25 amps... most likely not, but you can definitely count on feeling the current from it. There is more of a burn hazard from short circuiting of wires then any type of voltage arch. It's best to have the power supply turned off when splicing, or if your hands are wet.

Isn't this exactly what I said in the post that Billy agreed to?:waving:
Though the higher the voltage the greater the buzz. UL chose 15V limit for a reason. Who am I to challenge them?

It's much easier to comply with an inspectors ruling (requiring UL rated equiupment) than to attempt to fight them. I've got much bigger fish to fry and I can get along just fine with 15V. If you are using a Good transformer that puts out constant power and is giving you 15v out of the transformer when you are fully loaded then there will be very rare occasion that you would ever need more power. Keep your transformers within 100' of one another on jobs and use a X-10, UPB or a 12V relay if you want them to trigger together. You'll get along just fine.
Don't taser me Bro!

irrig8r
12-16-2007, 01:21 PM
Don't taser me Bro!

Interesting topical quote.....

steveparrott
12-17-2007, 08:56 AM
To clarify how amps and volts play into electric shock - The amperage that comes into play in an electric shock is based solely on the voltage of the source and the resistance through the body.

Current (Amps)= Voltage / Resistance (ohms)

Whether you are contacting a lighting circuit carrying 25 amps or 1 amp is irrelevant. Loads which are external to the through-the-body circuit do not affect the severity of the shock through the body.

The UL 25-amp limitation to the secondary circuits is entirely meant to prevent fire - it has nothing to do with electric shock.

steveparrott
12-17-2007, 09:07 AM
Excellent post Billy. That statement that nobody has ever been hurt from 30 volts or less is absolutely ludicrous and unfounded. I can't believe that some people would be so unscrupulous to suit their own agenda to perpetuate a statement like that. I would bet that even the slightest shock to someone with a pacemaker or a weak heart could be potentially fatal.
I'm sorry but it's not worth potentially harming someone over a landscape light system operating at higher than 15 volts.


Pete, with all due respect, I've spent days pouring through every engineering and safety database including OSHA, NIOSH and CDC records. I failed to find a single incident of serious injury from contact with any voltage below 30 volts. In addition to this anecdotal evidence, studies with animals and human volunteers confirm these statements on safety.

Your accusation of 'unscrupulous' behavior is more fairly applied to those whose agenda is to conflate the notion that low voltage is dangerous.

johnh
12-17-2007, 11:00 AM
I agree with Pete. The fact is the higher the voltage, the higher the propensity to penetrate the skin, allowing the current to travel through the body. The resistance of the skin is greatly diminished with contact with water, (in particular salt water {sweat}). The studies that Steve refers to both by Prof. Dalziel in the 1940's, and more recently by the IEC, both put the "let-go" threshold at 16mA which when considering the resistance of the human body at 1000 ohms (generally accepted as the impedance for hand to hand contact in saltwater wet conditions) translates into 16V as the maximum voltage. (Ohm's Law I=E/R or Amps=Volts/Ohms, 0.016=16/1000) This is reduced for women and children. It is further reduced if there is any break in the skin. 23V is the maximum for before severe pain and difficutly breathing. By limiting to 15V, the UL is eliminating the pain threshold.
Again, in the hands of a professional, higher voltages are safe, but the concern is for the general public.
Steve is correct that the 25A rating only serves to reduce fire hazzard, we just went through this with our local electrical authority who was trying to limit us to class 2 (5A) installations. Our point to them was that public safety could better be served by limiting voltage (currently at 30V) to 15V. This seems to be the direction we are going, but I'll keep everyone posted as to how the negotiations turn out.
JH

INTEGRA Bespoke Lighting
12-17-2007, 11:09 AM
I agree with Pete. The fact is the higher the voltage, the higher the propensity to penetrate the skin, allowing the current to travel through the body. The resistance of the skin is greatly diminished with contact with water, (in particular salt water {sweat}). The studies that Steve refers to both by Prof. Dalziel in the 1940's, and more recently by the IEC, both put the "let-go" threshold at 16mA which when considering the resistance of the human body at 1000 ohms (generally accepted as the impedance for hand to hand contact in saltwater wet conditions) translates into 16V as the maximum voltage. (Ohm's Law I=E/R or Amps=Volts/Ohms, 0.016=16/1000) This is reduced for women and children. It is further reduced if there is any break in the skin. 23V is the maximum for before severe pain and difficutly breathing. By limiting to 15V, the UL is eliminating the pain threshold.
Again, in the hands of a professional, higher voltages are safe, but the concern is for the general public.
Steve is correct that the 25A rating only serves to reduce fire hazzard, we just went through this with our local electrical authority who was trying to limit us to class 2 (5A) installations. Our point to them was that public safety could better be served by limiting voltage (currently at 30V) to 15V. This seems to be the direction we are going, but I'll keep everyone posted as to how the negotiations turn out.
JH

Great follow up post here John. I for one appreciate the attention to detail and the sources that you provide to support your posts.

johnh
12-17-2007, 11:10 AM
Sure one could argue, and probably successfully that 30V is safe. But could you argue that 15V is not safer? I guess I don't understand the need for voltages higher than 15V for our applications. I am gathering that Pete has been pretty successful designing his systems around this limitation, I know our contractors around here have also, so why fight it?
JH

johnh
12-17-2007, 11:15 AM
I'm sorry but it's not worth potentially harming someone over a landscape light system operating at higher than 15 volts.

To clarify, when I said in a previous point that I agree with Pete, I was referring to this statement, not that I agree with everything Pete says or has said. No offense Pete!

JH

INTEGRA Bespoke Lighting
12-17-2007, 11:37 AM
Sure one could argue, and probably successfully that 30V is safe. But could you argue that 15V is not safer? I guess I don't understand the need for voltages higher than 15V for our applications. I am gathering that Pete has been pretty successful designing his systems around this limitation, I know our contractors around here have also, so why fight it?
JH

Exactly! "Why fight it?" Is 30V safe? Yes, no, maybe... whatever the answer is, 15V is surely indisputably safer. UL and CSA certainly think that is the case.

I have said it before and will say it again:

1: Know your product, know your systems, understand the limitations of the code and certifications that exist for the application and build systems to meet those codes, certifications and limitations. It isn't rocket science.
2: The public and the untrained commercial sector need to be kept safe, long after the lighting system has been installed. When have you ever encountered a caretaker, maintenance guy or home owner who didn't assume that what we do is "all 12 volts, right?"
3: Finally, we all want this industry to flourish right? So why complicate systems with wildly ranging voltages from 11 to 22v (and hopefully not beyond)? LV lighting used to suffer from a bad reputation... why not standardize the industry so that mistakes after installation are not made. These mistakes cost us all because if the system is not standardized and other, untrained individuals start to make adjustments and changes (it does happen!) then the systems fail and ultimately this gives the whole industry a bad name. Who hasn't heard something along the lines of: "Oh I don't want that low voltage junk. I had one of those system a while ago at home and it never worked. What a waste of money."

K.I.S.S.

JoeyD
12-17-2007, 06:15 PM
WOW......So wheres UL to save all the irrigators when wiring up 24v irrigtion wires in "wet locations?"

irrig8r
12-17-2007, 08:16 PM
WOW......So wheres UL to save all the irrigators when wiring up 24v irrigtion wires in "wet locations?"

It's funny Joey, most of the time I read 27 or 28 V on irrigation control wires. I've gotten a little jolt now and then.. no biggee.

And often times sprinkler controllers are located in garages and control wires go through walls without any conduit....

In all my years I've never found a sprinkler wire get hot, although solenoids will if they are turned on with the water off....

But this is probably the key: amperage in sprinkler system control wires is a lot less than with lighting .. Solenoids are usually no more than 0.3 to 0.4 Amps inrush, and maybe 0.2 Amps holding...

pete scalia
12-17-2007, 09:02 PM
WOW......So wheres UL to save all the irrigators when wiring up 24v irrigtion wires in "wet locations?"

Cause their is no load on sprinkler wire. it's used for switching not to handle a load.

JoeyD
12-18-2007, 01:54 PM
SO whats the danger with the 22v tap upon wiring if you have no load on it?? if I am holding a 22v tap with 3 amps on it and I put both sides togeather it is going to burn me for a second until I pull it apart. But it is not going to electricute me nor will it even come close to killing me. Funny thing is I can get the same exact sensation from holding 2 ends of a 15v tap togeather with or without any amp draw. This UL1838 is a crock and no matter how much technical stuff you may cut from magazines I am going to go with what the NEC claims as safe. Wet salty sweaty hands or not, I have been doing this for way to long for you guys to keep trying to pull the wool over the eyes of the industry to believe that 17v is dangerous yet 15v is safe. Bottom line is if we never had a Malibu system we probably would never have UL1838. It was written for complete systems and is written to protect DIY homeowners and not PROFESSIONAL lighting installers. So to each his own, you use 15v max and big wire and pull 120v all over the place and we will promote using smaller wire, higher taps to compensate the VD and more affordable efficient systems. UL1838 is a subject that is always worth debate but it is so hard to debate online. Nate is working on a VD post for the Lawnsite.com community. He will address UL concerns and will also address VD. We always will tell you though if you would like further information on this or any other subject related to installing or designing low voltage lighting then please do not ever hesitate to contact myself or Nate directly on his cell at 760-580-4980. Nate has a tremendous ammount of experience here and that is why Unique has been so succesfull. We design our products for the professional installer.

My next post will be the results of the VD test.

Joey D.

JoeyD
12-18-2007, 03:26 PM
So my video guy is going to take a little longer to put this video together so I figured since Nate is working on a large response to this topic I would go ahead and get the results up here so we can keep the discussion moving.

There are going to be some that live by the fact that 15v is the maximum voltage you should use. They have their reasons, safety and UL/ETL, and if they feel they are protecting themselves from a problem then so be it. Nothing wrong with that. Then there will be some guys who will decide to use transformers that go beyond 15v for the sake of using smaller wire and traveling further distances while still ensuring 12v to each and every lamp. They are still UL/ETL approved safe and are also still well within the limitations of the NEC safety requirements for Low Voltage Lighting.

For this test I took what I would consider a very common situation in lighting. So here is the scenario: 200ft 12/2 run with 4x35w Par 36 lamps= 140watts.

Materials Used
1-Unique 840 I Force (118v at Primary Plug, 11.6-8v @ 12v Tap)
4-35w F225 Well Lights w/ 25ft 16/2 leads= 140watts
200FT of 12/2 Low Voltage Direct Burial Cable
Wired up in a Hub style format using 2 red wire nuts

Method 1

2(ac) x 12(wire value) x 200(12/2 run) x 11.67(amps on run) / 6530 (Circular Mills)
= 8.578 Volts of Drop

Method 2

200(12/2 run) x 140watts / 7500 (Cable Constant)
= 3.733 Volts of Drop

Method 3

11.67(amps on run) x .00162(12/2 wire resistance) x 200(12/2 run) x 2(ac)
= 7.562 Volts of Drop

Results

After I wired the run up, 4 35w fixtures in a Hub style wiring method I set the home run to 12v first to see what my VD would be. My Hub (first point of connection) measured at 5.9v and 6v fluctuating back and forth. So we can say that our VD is 6v. So that put Method 1 off by Positive 2.578volts, and put Method 2 off by Negative 2.267volts and Method 3 being off by Positive 1.562volts. But that can’t be the end of the test; you need to get the amperage up on the lamps before being able to really determine your VD. At the 12v tap I was only drawing 8amps on a run that should be pulling 11.67 amps.
So if I do my VD calculation, my VD was 6 volts so that would mean ideally that I would need to step my TF up to the 18v tap, which my TF has. So I bump it up to 18v and I am still only burning at 10.4volts at my Hub and only pulling about 10amps. So I then bump my run up to my 20v tap(19.8v @ 20v Tap) where I then was burning at 11.6-8v at my Hub, putting my lamps at 11.1-3v and my amperage at 11.5amps.

So what does this mean?

What it means is that my VD was actually 8.5volts and that is exactly what Method 1 calculated which means method 1 is actually the most accurate. Method 2 was off by negative 4.767 (almost 5 volts) which makes it the worst, and method 3 was off by negative .938 volt which puts it in second place and makes it pretty darn accurate.

So I ask Nate, why do we tell guys that Method 3 is the best to use when you have Method 1 in your book and it is much closer, practically perfect? His reason is that Method 1 although being so accurate is harder to remember. You can find resistance values for all sizes of wire where finding Circular Mills and Wire Values is not as easy to acquire for all sizes of wire. He then followed up and explained that the bottom line is the best method to use is by utilizing your volt meter when wiring your system. The VD methods should only be used for ball parking a job and for determining the size TF you will need and what voltage taps you will require. He then pulled another VD method out on me which he calls his own and is right on. He says when using a 35w lamp you will have a 1volt drop for every 100ft of 12/2 cable. That means with 4 35w lamps and 200ft of 12/2 cable that puts your VD at 8volts. Pretty darn accurate.


So again, once I get the video done I will post here and on my website. If you guys have another method you want to test just give it to me and I will utilize the same stuff for the same test, I have all the materials including exact TF and lights set aside to run any other test you guys would like.

Let me know what you guys think.

Joey D.

I attached section 5 from Nate's book that address's VD.

pete scalia
12-18-2007, 08:03 PM
SO whats the danger with the 22v tap upon wiring if you have no load on it?? if I am holding a 22v tap with 3 amps on it and I put both sides togeather it is going to burn me for a second until I pull it apart. But it is not going to electricute me nor will it even come close to killing me. Funny thing is I can get the same exact sensation from holding 2 ends of a 15v tap togeather with or without any amp draw.

Maybe no danger to you because you are young and healthy. Take an elderly person with a heart condition and it may be a different story. Call me crazy but getting burned is not fun and very painful. The day UL cerifies a transformer over 15 volts is the day I use em. Until then I'll stick to 15 volts. I have no trouble bringing 12v to the lamp and have no desire to prematurely burn lamps out lamps with a 22volt tap when I lose a bulb or two on that cable run.

pete scalia
12-18-2007, 08:13 PM
Pete, with all due respect, I've spent days pouring through every engineering and safety database including OSHA, NIOSH and CDC records. I failed to find a single incident of serious injury from contact with any voltage below 30 volts. In addition to this anecdotal evidence, studies with animals and human volunteers confirm these statements on safety.

Your accusation of 'unscrupulous' behavior is more fairly applied to those whose agenda is to conflate the notion that low voltage is dangerous.

You can't believe that your investigation was anywhere thorough . To make such a claim that no one has ever been seriously injured by less than 30 volts is ludicrous based upon your peripheral investigation. 15 volts was not just plucked from the air by UL. I have seen case after case where higher than 15v transformers dessimate lamps powered by higher volt taps. Not everyone changes a bulb immediately after it blows like they should. it's a domino effect and it's not pretty. even halogens don't last long when operating over 12 volts. Set aside safety and that alone is a real problem

JoeyD
12-18-2007, 09:36 PM
You can't believe that your investigation was anywhere thorough . To make such a claim that no one has ever been seriously injured by less than 30 volts is ludicrous based upon your peripheral investigation. 15 volts was not just plucked from the air by UL. I have seen case after case where higher than 15v transformers dessimate lamps powered by higher volt taps. Not everyone changes a bulb immediately after it blows like they should. it's a domino effect and it's not pretty. even halogens don't last long when operating over 12 volts. Set aside safety and that alone is a real problem

Pete, do you really think 15v to a lamp wont burn them out just as quick. Fact is if you are using a 22v tap you probably are hundreds of feet away and need it. It would be no difference if you were closer and need a 15v. That argument is weak, stick with the fact that 16,17,18,19.........30v is so much more dangerous than 14, and 15. The fact that lamps burn out has nothing to do with the higher taps as much as it does with an increase when you lose a lamp. 13, 14, and 15 v are capable of overloading a lamp just as 22v can.

Its all in how you test and wire your system. An unliscensed contractor or homeowner should not be wiring our systems. We build them for the professional that should know what happens when you touch 2 sides of the cable togeather and also what happens when you stick your tounge on a frozen metal pole.

But hey if you dont need 15v then more power to you, I have said it before and I will say it again, we make a UL1838 TF, we just dont sell many of them.

Joey D.

pete scalia
12-18-2007, 10:23 PM
Joey as much as I love you the higher voltage tap argument is not weak. When you have 11.8 volts at your homerun and you lose a 35 watt lamp you are in trouble on a long distant run with a higher than 15v tap. You are going to lose those other lamps very soon if you don't change that burnout immediately. Lamps were made to operate at 12v . They don't last very long at 12.5v and higher.

JoeyD
12-18-2007, 10:28 PM
Pete the chain reaction can and does happen when hooked up to taps 15v and below. Its all relative. If you are putting 12v on a run using a higher voltage tap you are going to increase the 12v no matter if its the 14 or 16v tap feeding it. This is just part of LV lighting. This is not a strong argument, do I have to break out the test equipment again?

pete scalia
12-18-2007, 10:36 PM
Pete the chain reaction can and does happen when hooked up to taps 15v and below. Its all relative. If you are putting 12v on a run using a higher voltage tap you are going to increase the 12v no matter if its the 14 or 16v tap feeding it. This is just part of LV lighting. This is not a strong argument, do I have to break out the test equipment again?

It doesn't take an electrical engineer.
The voltage drop from lamp load is greater than the loss of voltage due to resistance in cable
So if you are far out and get a burn out I'd rather be on a 15V tap than higher. The higher the tap in this instance the higher the voltage and the sooner the lamp will die.

JoeyD
12-18-2007, 10:41 PM
Quit avioding the fact that your 15 tap can create the same exact problem. That doesnt take an electrical engineer.

I will test it, and then let you know the results.

pete scalia
12-18-2007, 10:46 PM
The higher the tap the higher the voltage.

nate mullen
12-19-2007, 09:42 AM
Joey as much as I love you the higher voltage tap argument is not weak. When you have 11.8 volts at your homerun and you lose a 35 watt lamp you are in trouble on a long distant run with a higher than 15v tap. You are going to lose those other lamps very soon if you don't change that burnout immediately. Lamps were made to operate at 12v . They don't last very long at 12.5v and higher.


Pete, hey Buddy I'm a big fan and I am happy to set the record strait on this topic today and I will be setting the record straight on the NEC, UL 1838, 506, 1571, 1593, 2108, and the non existent 5058, as well as Voltage Drop..

I have sat back for my whole lighting career and watched how the industry has evolved and has ceased to evolve. There is no identity to this lighting industry. We as contractors sit here and have been taught by who? Yourself, a book that you cannot understand because you have no foundation, a manufacturer that has never installed a lighting job in their life...............I'm just about ready to get side tracked so back on point.

Increased Voltage to Lamps Above 12

FACT: you have 2 light bulbs @ about 100ft and you are using the 15v tap. This means you have a 3 volt drop shared between 2 fixtures, 1.5v per lamp. When one lamp burns out the other lamp will have 13.5v. At 13.5v the lamp life is dramatically reduced from 100% to 21% life which is 855 hours. If you had 15 volts at the lamp your life at the lamp is reduced to 5% of lamp life 215 hours. Above 15 volt.................what does it matter,.............fact is anything above 12 volts kills the lamp life.

THERE IS NO DIFFERENCE BETWEEN 13.14.15.16.17.18.19.20.OR 22 IT IS EXPONENTIAL EVEN AT 12.5 VOLTS THE LAMP LIFE IS 59% OF RATED LIFE. This is where it all gets back to proper wiring design.( more on this later)

So your right the higher the voltage the faster the lamp burns out. whether it burns out within 1 month or anything less it just does not matter.

I just have to say this, it is the NEC that is mandated across the US (and almost every other country), it is the bible when it comes to electricity NOT UL! Article 411 states 30v or less not 15. There is no need to discuss this further although I know it is going to be (please find me one job that has been turned down in the US, 10's of thousands of inspectors cant be wrong). If any of you wish to discuss this further I am more than willing to pay for a conference call and discuss this with great dialog.


To A Brighter future,
Nate

pete scalia
12-19-2007, 08:02 PM
Pete, hey Buddy I'm a big fan and I am happy to set the record strait on this topic today and I will be setting the record straight on the NEC, UL 1838, 506, 1571, 1593, 2108, and the non existent 5058, as well as Voltage Drop..

I have sat back for my whole lighting career and watched how the industry has evolved and has ceased to evolve. There is no identity to this lighting industry. We as contractors sit here and have been taught by who? Yourself, a book that you cannot understand because you have no foundation, a manufacturer that has never installed a lighting job in their life...............I'm just about ready to get side tracked so back on point.

Increased Voltage to Lamps Above 12

FACT: you have 2 light bulbs @ about 100ft and you are using the 15v tap. This means you have a 3 volt drop shared between 2 fixtures, 1.5v per lamp. When one lamp burns out the other lamp will have 13.5v. At 13.5v the lamp life is dramatically reduced from 100% to 21% life which is 855 hours. If you had 15 volts at the lamp your life at the lamp is reduced to 5% of lamp life 215 hours. Above 15 volt.................what does it matter,.............fact is anything above 12 volts kills the lamp life.

THERE IS NO DIFFERENCE BETWEEN 13.14.15.16.17.18.19.20.OR 22 IT IS EXPONENTIAL EVEN AT 12.5 VOLTS THE LAMP LIFE IS 59% OF RATED LIFE. This is where it all gets back to proper wiring design.( more on this later)

So your right the higher the voltage the faster the lamp burns out. whether it burns out within 1 month or anything less it just does not matter.

I just have to say this, it is the NEC that is mandated across the US (and almost every other country), it is the bible when it comes to electricity NOT UL! Article 411 states 30v or less not 15. There is no need to discuss this further although I know it is going to be (please find me one job that has been turned down in the US, 10's of thousands of inspectors cant be wrong). If any of you wish to discuss this further I am more than willing to pay for a conference call and discuss this with great dialog.


To A Brighter future,
Nate

Finally a fan. You see you numbskulls Nate Mullen knows class when he sees it. I'm a huge fan of you too Mr. Mullen. Can I call you Nate?

johnh
12-22-2007, 01:04 AM
Pete, hey Buddy I'm a big fan and I am happy to set the record strait on this topic today and I will be setting the record straight on the NEC, UL 1838, 506, 1571, 1593, 2108, and the non existent 5058, as well as Voltage Drop..
[JohnH]How about we let the authority set the record STRAIGHT? I have posed the question(s) to UL, the NFPA, and the IAEI, let's see what their responses are. And by the way, UL 5058 may not exist, but 5085(Joey transposed some numbers from a previous post) very much does exist. It is the binational code that your outdated now superseded CSA standard conforms to.
I have sat back for my whole lighting career and watched how the industry has evolved and has ceased to evolve. There is no identity to this lighting industry. We as contractors sit here and have been taught by who? Yourself, a book that you cannot understand because you have no foundation, a manufacturer that has never installed a lighting job in their life...............I'm just about ready to get side tracked so back on point.

Increased Voltage to Lamps Above 12

FACT: you have 2 light bulbs @ about 100ft and you are using the 15v tap. This means you have a 3 volt drop shared between 2 fixtures, 1.5v per lamp. When one lamp burns out the other lamp will have 13.5v. At 13.5v the lamp life is dramatically reduced from 100% to 21% life which is 855 hours. If you had 15 volts at the lamp your life at the lamp is reduced to 5% of lamp life 215 hours. Above 15 volt.................what does it matter,.............fact is anything above 12 volts kills the lamp life.

THERE IS NO DIFFERENCE BETWEEN 13.14.15.16.17.18.19.20.OR 22 IT IS EXPONENTIAL EVEN AT 12.5 VOLTS THE LAMP LIFE IS 59% OF RATED LIFE. This is where it all gets back to proper wiring design.( more on this later)
[JohnH]Except that there is a significant difference in the amount of heat generated from a 12V lamp operating at 15V and one operating at 22V.
So your right the higher the voltage the faster the lamp burns out. whether it burns out within 1 month or anything less it just does not matter.

I just have to say this, it is the NEC that is mandated across the US (and almost every other country), it is the bible when it comes to electricity NOT UL! Article 411 states 30v or less not 15. [JohnH] If the UL is so inconsequential, why do your transformers not say "conforms to NEC Article 411", why bother listing them at all, and labelling them as conforming to UL Standards?There is no need to discuss this further although I know it is going to be (please find me one job that has been turned down in the US, 10's of thousands of inspectors cant be wrong). If any of you wish to discuss this further I am more than willing to pay for a conference call and discuss this with great dialog.


To A Brighter future,
Nate

We may have a different hierarchy here in Canada, the CSA who develops the standards and provides the testing (others like UL, ETL, CE are also acceptable, as long as they are to Canadian standards) also writes the CEC (equivalent to NEC). Then there are the local authorities that enforce the code. But the CSA standards and the CEC are closely tied together, one referring to the other.
Do the NEC and UL not have a similar symbiotic relationship?
JH

nate mullen
12-23-2007, 10:00 AM
We may have a different hierarchy here in Canada, the CSA who develops the standards and provides the testing (others like UL, ETL, CE are also acceptable, as long as they are to Canadian standards) also writes the CEC (equivalent to NEC). Then there are the local authorities that enforce the code. But the CSA standards and the CEC are closely tied together, one referring to the other.
Do the NEC and UL not have a similar symbiotic relationship?
JH

If the jobs are being inspected they need to be listed by a NRTL. at my last count there were 14 including ETL and UL. UL is a great company but all they do is wright standards. Then they come up with tests to meet those standards. 1838 was intended for lighting kits with every single conponate being tested and sold together, the wire, lamps, connectors,fixtures. With the expect ion of Malibu kits I know of nobldy that does this. I'm still waiting for some one to tell me why 120 volt lighting is OK .....if 1838 is the rule at 15 volts...by the way does't Kitchler, Nightscaping, Hadco, Vista and most other sell 120 volt lighting...........So back to UL standards there are many standards: under 15 volts, under 30 volts. over 30 volts to 120 volt's or higher. But make no mistake in the USA it is the NEC that stated what is legal or not legal. I really don't care .....I make all transformer's to comply with all listing for all standards for all uses.
To a Brighter Future.
Nate