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  #31  
Old 12-08-2007, 04:40 AM
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INTEGRA Bespoke Lighting INTEGRA Bespoke Lighting is offline
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Quote:
Originally Posted by Chris J View Post
No, no. This scenario dictates 2.13v of voltage drop from my calculations. Again, you are not multipying by two. Your volt meter after finalizaton will confirm your methods. You should always check the voltage at your fixtures after everything is hooked up. I'm suprised that you guys aren't doing this.
Gee thanks for the great tip Chris.... It never dawned on me to ever check the voltage at my fixtures.... ummm how would I do this? Should I stick the wires on my tongue to see how they taste or is there a meter or something that I could use?

OF COURSE the voltage is checked at the fixtures! 11.3 is my fav. and I take great pride at 'engineering' my circuits to deliver as close as I can get to that.

As for different voltage drop calculations and techniques, there are many different ones to choose from. The NS method has always served me well. I believe you will find that the Cable Constant they use in their method is different from the ones you use... it takes into account the AC circuit and the full run of the wire so you dont have to multiply the length by two

Have a great weekend.
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  #32  
Old 12-08-2007, 09:39 AM
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Originally Posted by Chris J View Post
This is probably the first time I've had a problem with you, but I'm gonna speak my peace. If you're such a good friend of Matt, then you should just go ahead and do the job for him and provide him with a little knowledge. Or, you could call him directly, and tell him over the phone in 5 minutes everything you know about lighting?
The first post of this forum is for "home owners" and/or "do it yourselfers".
It is clearly explained that we professionals make our living from designing and installing quality lighinting systems. Please don't try to defend someone who is not a lighting pro that happens to wander upon this forum. We are not here to help people take business from our individual companies, nor should you. Even though this person might be a good person, or even a great friend, he is still not a lighting contractor. This forum is for lighting contractors!!
No offense, but you hit a nerve.
So then you have someone around my parts that could fix up my system for me? Why would I pay someone to come out and tell me what I could hopefully learn in this forum from people who are here to help other contractors; I'm not stupid around the house, I just dont know electrical systems like people who congregate in here. I mentioned right off the bat that I dont do lighting, dont care to do it and dont plant to get into it, but I wanted a simple and CHEAP system at my place, which I got. There is no denying I bought close to the cheapest stuff you can get (though there is cheaper). If my ignorant post is such a waste of time to you, then why spend time writing three responses? How is Gregg helping me from CA going to affect you in FL or Scalion in New York? Is your bottom line going to suffer this year because I didnt hire a real lighting contractor for my house? Gregg did help by providing a little knowledge, if you dont care to read it because you wouldnt have done the same, then get the F out of this thread.

I appreciate everyone that is willing to help and I understand my system and electrical jargon now too, especially when related to plumbing/irrigation.

Maybe you can get Sean to screen all members who want to "enter" the lighting forum to make sure they are full-fledged lighting contractors. Or you can just keep your nose up there in the clouds with only your lighting buddies. I heard stories of some people in this lighting forum, thanks for confirming it.
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  #33  
Old 12-08-2007, 09:52 AM
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I take it your going for a quick easy homeowner fix.

Couple options here... I got a few transformers removed from jobs... mutitap kichler AZT transformers you can have for CHEAP... they are also 600w units so if you wanted to expand you could.

You can rewire and bring your home run into the middle of that run so you esentially have a T or you can loop it back. I doubt your getting 12v out of that box anyways. You still definatly wont be in spec but it will be more even.

Since you have no intrest in spending alot of money I would get a used multitap (ask a lighting guy in your area or im sure several here have some) or pick up a 300w new one someplace. Then run a main line to the center of your other wires or where you put a splice. Guys... he doesnt wanna mess with calculations... he is happy with the way the first run looks. He doesnt care to spend the money for pro grade installations or materials. He can make this work out. Would any of us do it like this ? prolly not but in his situation it will work.

bottom line... your transformer will keep you from obtaining desireable results. Multip tap and T is will be your easiest most cost effective fix.

Last edited by Pro-Scapes; 12-08-2007 at 09:59 AM.
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  #34  
Old 12-08-2007, 10:43 AM
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Originally Posted by Pro-Scapes View Post
I take it your going for a quick easy homeowner fix.

Couple options here... I got a few transformers removed from jobs... mutitap kichler AZT transformers you can have for CHEAP... they are also 600w units so if you wanted to expand you could.

You can rewire and bring your home run into the middle of that run so you esentially have a T or you can loop it back. I doubt your getting 12v out of that box anyways. You still definatly wont be in spec but it will be more even.

Since you have no intrest in spending alot of money I would get a used multitap (ask a lighting guy in your area or im sure several here have some) or pick up a 300w new one someplace. Then run a main line to the center of your other wires or where you put a splice. Guys... he doesnt wanna mess with calculations... he is happy with the way the first run looks. He doesnt care to spend the money for pro grade installations or materials. He can make this work out. Would any of us do it like this ? prolly not but in his situation it will work.

bottom line... your transformer will keep you from obtaining desireable results. Multip tap and T is will be your easiest most cost effective fix.
Sweet. I like the sound of the T. If I run to a T, and each side of the T is going to remain #12, should that line to where it splits be #12, or better?

And if I could move the TF closer to the actual runs, that would help some too?

Im going to check voltage on the TF and get back to you on that Kichler. What is cheap for something like that?
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  #35  
Old 12-08-2007, 11:43 AM
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Originally Posted by irrig8r View Post
So if you go back to the first message it sounds like Matt says he has 2 runs of 100 ft of 12/2. One run has 30 W, the other has 40 W. That's a total of 70 W on 200 ft of cable. (As I read it, the two runs are spliced together away from the transformer somewhere, distance not made clear)

So, I would take each run, making sure I was using 12/2 and not 14/2 or whatever else Malibu sells these days, and attach them to the transformer separately, because otherwise it's 70 W over 200 ft.

Instead we have 30 W over 100 ft. where you get 2.50 A x .00162 x 200 L = 0.81 Vd
and 40 W over another 100 ft. where you get 3.34 A x .00162 R x 200 L = 1.09 Vd

These numbers are acceptable.

Using the same mathod, with 70 W on 200 ft of wire the calculation is something like this:

5.84 A x .00162 R x 400 L = 3.79 Vd.

Totally unacceptable.


So, first thing to do, in this case, is run the two lines separately from the TF.

Do you agree Joey?
I do agree that he should pull two home runs
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  #36  
Old 12-08-2007, 11:46 AM
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Quote:
Originally Posted by James Solecki - INTEGRA View Post
Gee thanks for the great tip Chris.... It never dawned on me to ever check the voltage at my fixtures.... ummm how would I do this? Should I stick the wires on my tongue to see how they taste or is there a meter or something that I could use?

OF COURSE the voltage is checked at the fixtures! 11.3 is my fav. and I take great pride at 'engineering' my circuits to deliver as close as I can get to that.

As for different voltage drop calculations and techniques, there are many different ones to choose from. The NS method has always served me well. I believe you will find that the Cable Constant they use in their method is different from the ones you use... it takes into account the AC circuit and the full run of the wire so you dont have to multiply the length by two

Have a great weekend.
The NS method you are using is wrong James. It was designed for DC. Nate is going to chime in on this so I will leave it up to mr VD himself. Remember we developed our entire system because of that 7500 constant method that NS was preaching even back before I was born. Nate tried it and it didnt work, Nate called Bill (this is back when Nate was a big contractor) Bill says you have a bad volt meter. Nate buys a new volt meter , same method, bad voltage. Hence the new Multi Tap and Nate digging into the electrical formula books to re discover the correct method. He didnt invent it it was always there.
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  #37  
Old 12-08-2007, 11:55 AM
ccfree ccfree is offline
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Craig Freeman CLVT #0412

Hey Joey, I did a study on the voltage drop constant method. I did the math with the exact footages of the wire and load. It is accurate to within 1/10th of a volt. I did it with the daisy chain, tee, and hub methods for wiring. The nightscaping formula works...if you times if by two.
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  #38  
Old 12-08-2007, 12:09 PM
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Originally Posted by ccfree View Post
Hey Joey, I did a study on the voltage drop constant method. I did the math with the exact footages of the wire and load. It is accurate to within 1/10th of a volt. I did it with the daisy chain, tee, and hub methods for wiring. The nightscaping formula works...if you times if by two.

If you times by 2 it makes it much closer, yes you are absolutly correct Craig. But why not just do it the right way. Forget about cable constant. You need to times it by the wire resistance.

Nate is going to break it down on this subject sometime soon as he does in his book. (but he loves reading this forum so he would like to chime in) There are a few methods that will put you close, the method we use and a few others now use (manufacturers) is the most accurate.

It's a whole other subject to discuss now distributing that voltage. The VD formula and your TF can only ensure 12v tot he first connection. Everything there after is soley based off of wire design. T and Daisy chain have way to many rules to come out with results that just make voltage "close". Hub is the only way to distribute exact even voltage to all lamps.

Joey D.
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  #39  
Old 12-08-2007, 12:12 PM
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Quote:
Originally Posted by hoskm01 View Post
Sweet. I like the sound of the T. If I run to a T, and each side of the T is going to remain #12, should that line to where it splits be #12, or better?

And if I could move the TF closer to the actual runs, that would help some too?

Im going to check voltage on the TF and get back to you on that Kichler. What is cheap for something like that?
Moving the trans closer would definatly help with the drop but without a multi tap your still more than likely going to have issues.

first step... get the EXACT lenghts of your runs and the voltage readings at the trans. If you have 7 fixtures and they are equally spaced I would probably bring the T in at the center fixture. Since they are only 10w and you have 12ga I doubt your drop would be noticable to the eye.

How bout some pics... this would help tremendously. Perhaps we could help you with a more effecient design. But rememeber... come spring your going to be helping me with my irrigation!

PM me about the trans I dont wanna discuss a price in public but trust me. Its a steal. Also ask your local irrigation dist about a multi tap 300w. I think I only have 5 units that are all 600w... .
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  #40  
Old 12-08-2007, 12:33 PM
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Pics, readings, drawings, all coming. Will have them up tomorrow.
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