Troubleshooting Low Voltage Landscape Transformer


Old 01-02-16, 07:11 PM
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Join Date: Sep 2004
Location: Florida
Posts: 30
Troubleshooting Low Voltage Landscape Transformer

I have a low voltage light placed under a waterfall that keeps burning out. All along I assumed that water was penetrating the seal and would replace the bulb. Today, I decided to spend more time diagnosing the problem as I didn't see any water inside and the replacement bulb didn't work. I replaced the interior socket and after multiple trips to lighting store figured out the problem was also that the connection to other low voltage wires became loose. That was also a contributing factor. So, I replaced the wire nut and some fresh electrical tape and hope that problem is resolved on a more permanent basis.

However, when I went to the transformer to re-adjust the timer tonight (which I never do), the stainless steel enclosure holding the transformer was extremely hot to the touch. If I kept my finger on the enclosure it would have burned me. I immediately unplugged the transformer.

Here is what I know and don't know:

1) Is it possible that I reversed the wiring today on the low voltage socket such that it is causing the heat overload at the transformer? (my limited electrical experience says that if it works, then it isn't the problem but I would appreciate confirmation).

2) The original landscape installer cut corners on every part of the project and hosed me completely. He walked off the job after getting paid in full (my mistake). Everything he did has been replaced and I now question if he put in the wrong specs on the transformer.

I am running 17 low voltage 20W halogen bulbs.

12 bulbs: Halogen JC GY6.35 12V 20W
5 bulbs: Halogen MR16BAB/L/HX 12 V 20W

The transformer shows 300W max rating. Until now I never investigated/researched the transformer.

What should I do next?

If your suggestion is to buy another transformer, please tell me what brand/model?

If your suggestion is to replace the bulbs with non-halogen bulbs, please tell me what to buy?

Thanks in advance.

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Old 01-02-16, 07:42 PM
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Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 4,292
First do the math. 17 20watt bulbs needs 340 watts. Your transformer can only put out 300 watts.
Yes, it will get hot and may kick out any internal overload protector.
You need a transformer in the 400 - 500 watt range.

As to the wiring, the voltage is a nominal 12 volts AC so it does not matter which wire is on which terminal.

Do some shopping. Look for the proper size, U.L. label, and probably a brand name in low voltage outdoor lighting.
Old 01-02-16, 07:52 PM
ray2047's Avatar
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Join Date: Mar 2006
Location: USA
Posts: 33,049
So, I replaced the wire nut and some fresh electrical tape
Only armatures tape wire nuts. One of the purposes of a wire nut is to replace tape. However if the connection is exposed to water you might want to use silicone filled wire nuts. Example:

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