Voltage Drop Compendium

[pete scalia]

Originally Posted by irrig8r

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]

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]

Originally Posted by Chris J

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]

Originally Posted by Firefly Prof. Lighting

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]

No doubt. He obviously has things dialed in a lot better than I do. Cudos to you Chris.

[johnh]

Originally Posted by James Solecki - INTEGRA

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;




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]

Originally Posted by irrig8r

(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]

Originally Posted by Chris J

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]

Originally Posted by johnh

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




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]

Originally Posted by johnh

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




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.