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  #1  
Old 03-31-2014, 11:58 AM
cmatthews77 cmatthews77 is offline
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Running low voltage landscape 100+ feet from transformer

This weekend I was attempting to run low voltage landscape lighting to a place a good distance from the transformer. Specifically, the line ran nearly 100 feet before reaching the first light.

I was using 12/2 guage wire and was very much under the total wattage allowed for the 300 watt transformer, however the lights were EXTREMELY DIM and kept tripping the transformer after a few seconds.

My question is, what can be done to resolve this? Would switching to a 10/2 guage wire solve the problem? Do I need a junction box at 100 feet and then my wires to the lights run from there?

I've also read where LEDs may also help.

Any help would be greatly appreciated?
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Old 03-31-2014, 12:09 PM
WenzelOSLLC WenzelOSLLC is offline
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I'd say the wire is creating too much resistance because of the long run. Stepping up gauge could help. It there a way to get the transformer closer?

I don't do enough LVL to know off hand and I don't have a voltage drop reference handy.
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Old 03-31-2014, 12:13 PM
WenzelOSLLC WenzelOSLLC is offline
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What voltage lights and transformer are you using? You're looking at about a 2v drop just to the first light assuming you're using about 150w of lights.

L.E.D. could help because it uses less watts and thus less of a voltage drop. Stepping up the transformer a few volts would compensate as well as the wire gauge.
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Old 03-31-2014, 01:20 PM
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Lite4 Lite4 is offline
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Wow, where to start.

1. Are you using a professional, multi-volt transformer or a lowes, home cheapo kind?
2. What is the total load of your run (how many total watts on that home run?)
3. What wiring method did you use?- Daisy chain, T, Hub?

Can't really help you until we get more info
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Old 03-31-2014, 01:28 PM
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Lite4 Lite4 is offline
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Quote:
Originally Posted by WenzelOSLLC View Post
What voltage lights and transformer are you using? You're looking at about a 2v drop just to the first light assuming you're using about 150w of lights.

L.E.D. could help because it uses less watts and thus less of a voltage drop. Stepping up the transformer a few volts would compensate as well as the wire gauge.
Hi Wenzel, you voltage calculations are off a bit. Here is the formula you would want to use:

using the calculation: VD=AxRxLx2

You would have a voltage drop of 6.07 volts at the first light if you indeed had 150' of 12/2 with a 150 watt load.

If this person is using a single tap transformer (12v only), his lights will be incredibly dim. He would need to place his lead wire in the 18v lug to counteract the VD and give him 12v at the first light.
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Old 03-31-2014, 01:42 PM
WenzelOSLLC WenzelOSLLC is offline
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Lite, thanks for actually doing the math; I just grabbed the numbers off a site that had a pretty close example. Like I said, don't do a whole lot of lighting but looking to get into it.

Better for the OP too having the right numbers.
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Old 03-31-2014, 02:00 PM
cmatthews77 cmatthews77 is offline
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Thanks for the quick replies... More info as requested:

1. It's a 12 vac transformer only (yes the big box store kind). Note, this isn't a big time professional lighting job but rather helping a friend DIY.

2. The set up is I have one transformer (300w max, 12 vac only as mentioned above) with two runs coming out. The first run of 12/2 wire powers 4 20 watt spot lights. These 4 lights are daisy chain designed but all pretty close proximity to the power source. This part of course is working fine.

The second part or the addition was to run a second line roughly 100 feet or so and power 4 to 5 more 20 watt spot lights. The first light is probably at 80-90 feet and and a total distance of maybe 120-130 feet. I had used 12/2 guage wire again. This is causing the transformer to trip within just a few seconds. Both when running both lines into the box and also tried just running the long distance line without the short run hooked up.

3. The long stretch was also a daisy chain set up which I now know just won't be possible at that distance so I suppose I'll look for a junction box so I can spider the lights from the box?

Curious as to whether the 10/2 guage wire will solve the the transformer tripping as a result of voltage drop. Is that sufficient wire to run that distance. Can I use the junction box along with the 10/2 wire as the best fix?

Thanks in advance

Last edited by cmatthews77; 03-31-2014 at 02:07 PM. Reason: accidentally posted before finished typing
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Old 03-31-2014, 04:37 PM
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Lite4 Lite4 is offline
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Quote:
Originally Posted by cmatthews77 View Post
Thanks for the quick replies... More info as requested:

1. It's a 12 vac transformer only (yes the big box store kind). Note, this isn't a big time professional lighting job but rather helping a friend DIY.
This is problem #1. You will never be able to counteract the voltage drop with that transformer- it simply wasn't made for that kind of distance and load. Your friend will need to purchase a multi-tap transformer (12-22v) to offset the voltage drop if you are going to continue on with using halogen lamps.

2. The set up is I have one transformer (300w max, 12 vac only as mentioned above) with two runs coming out. The first run of 12/2 wire powers 4 20 watt spot lights. These 4 lights are daisy chain designed but all pretty close proximity to the power source. This part of course is working fine.


The second part or the addition was to run a second line roughly 100 feet or so and power 4 to 5 more 20 watt spot lights. The first light is probably at 80-90 feet and and a total distance of maybe 120-130 feet. I had used 12/2 guage wire again. This is causing the transformer to trip within just a few seconds. Both when running both lines into the box and also tried just running the long distance line without the short run hooked up.
With that load and distance, you are probably experiencing about 3-4 volts of drop (enough to make the lights a very dim orange and totally defeat the purpose of having lighting). You may get 20-25% of the rated light output at that voltage. The total wattage on that run is not the problem. You could load that 12/2 up to around 180 watts and still be in NEC regs. The problem you are having is a direct short at one of your connections. I am assuming if your friend purchased the throw away lights from the box stores, that you are also using the terrible "pierce point" connectors that came with them. This is probably the worst connection possible next to twisting the wires together and wrapping them with electrical tape. I would take the connections apart and cut the crazy pierce point connections off. Go get some grease filled wire nuts and connect it properly (wire nuts are still not my favorite connector, but are homeowner friendly and much better than those silly clip connectors the manufacturer gives you.

3. The long stretch was also a daisy chain set up which I now know just won't be possible at that distance so I suppose I'll look for a junction box so I can spider the lights from the box?
It doesn't matter what junction box you use. You won't improve on the voltage any. The lights will still be dim until you upgrade the transformer to a multi-volt unit. You need this one Here

Curious as to whether the 10/2 guage wire will solve the the transformer tripping as a result of voltage drop. Is that sufficient wire to run that distance. Can I use the junction box along with the 10/2 wire as the best fix?
Forget the 10/2- Fix the connections so it doesn't short and get a transformer to offset the voltage drop properly. You should be in good shape then.

Good luck



Thanks in advance

See notes above in blue- hope this helps
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Old 03-31-2014, 07:02 PM
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meets1 meets1 is offline
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Great advice....not hijack thread but having issues myself. I use all kichler lighting and transformers. Well I installed a large timberTeck deck 1.5 years ago. Home owner is home from winter vacation, 5 of the 12 lights are out. These are 3 watt LED Post Cap Module lights from Timber Tech. Longest run I assume is 40ft away from transformer. Using a Kichler 15E60 BK. Good for 60 watts. I took some apart the other day and found nothing - connections are tight, sealed yet for what I could tell etc. THing is the first three lights dont work, skip a few then another doesnt work, skip two more then one last one furtherest away doesnt work. Timber Tech says its the transformer since I did not use there transformer to begin with and that is it. There very littlw help. I sumbled onto this thread tonight and thoughts are I need to ask a few questions.
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Old 03-31-2014, 10:25 PM
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Lite4 Lite4 is offline
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Originally Posted by meets1 View Post
Great advice....not hijack thread but having issues myself. I use all kichler lighting and transformers. Well I installed a large timberTeck deck 1.5 years ago. Home owner is home from winter vacation, 5 of the 12 lights are out. These are 3 watt LED Post Cap Module lights from Timber Tech. Longest run I assume is 40ft away from transformer. Using a Kichler 15E60 BK. Good for 60 watts. I took some apart the other day and found nothing - connections are tight, sealed yet for what I could tell etc. THing is the first three lights dont work, skip a few then another doesnt work, skip two more then one last one furtherest away doesnt work. Timber Tech says its the transformer since I did not use there transformer to begin with and that is it. There very littlw help. I sumbled onto this thread tonight and thoughts are I need to ask a few questions.
If you have good voltage and your connections are sound, it is most likely that the LEDs have failed. Just because a manufacturer says "this LED will last X amount of hours" doesn't mean it actually will. I have never heard of timer tech, but I would bet you $10 your LEDs are dead. The whole "their transformer" thing, is just a jacked up excuse for them to walk away from a cruddy product offering. They probably know their products stinks, they are just looking for a way out so they don't have to reimburse you for them. It doesn't matter what transformer you use- 12v is 12v.

Are those kichler LED lamps you are using in the timber tech fixtures? Get a volt meter with probes and check the sockets. If you have voltage its the lamps, if no voltage- then probably the socket or connection.
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