Blowing out PAR 36s left and right....

[fakie99]

Good morning -

In the fall of 2010, we installed a 30+ fixture system for a very good client. The system is comprised of 3 transformers, roughly 14 well lights (PAR 36), and the remainder are MR16 bullets and path lighting. The PAR 36 fixtures have never been right; I've been through about 30 bulbs now (for being old headlights, these things aint cheap as most of you know....). Each time I get the system up and running again and replace the fixtures, they all test at 10.6 -11.6 volts. Then, they start blowing within 2-3 days. The prob is mostly on two transformers, one especially.

The loading on it goes like this:

Transformer 1 (300W), run 1 - 13V tap (on circuit 1), 3 lamps, 11V, 11.3V, 11V
Transformer 1 (300W), run 2 - 13V tap (on circuit 2), 3 lamps, 11V, 11.1V, 11.2V

Again, it's always the well lights - everything else is fine. I have installed good, GE bulbs. All wiring is 12 ga, and connections are silicone nuts. One thing - because the fixtures have been moved / bulbs changed so often, the wiring where it meets the lamp is worn and probably not clean - not sure this could be causing burnouts so quickly though.

So, I'm at the end of my rope on this one - any thoughts on what might be happening? My feeling at this point is that it's fluctuations in primary voltage, but how the heck do you prove that... I have toyed around with getting some direct burial voltage regulators just to see if that fixes it. If it does, then primary voltage is likely the problem.

Thanks for your help

[Lite4]

That's odd. Your voltage range is fine on the pars. I have always had very good luck with GEs. Some I have in my yard are going on three years usage.

Your thought on primary power fluctuations could have merit. You might install surge protection in the panel to smooth out spikes, this will help protect their home electronics too. That's probably where I would start.
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[steveparrott]

Some utilty companies will respond to this type of complaint by temporarily installing a device that records voltage fluctuations over time. If the power problems come from the utility (and not the home) they are required to fix it.

[LLC RI]

You didn't say specifically what PAR36 lamps you are using. The lamp life on those varies considerably. I don't use too many PAR36's but I do like the Halozene ones.

Also worth asking is if your fixtures are open top - ie the lamp is exposed to the elements, or is there a plastic cover or some other lens on top?

Another thought would be to convert them as they burn out to a quality PAR 36 LED retrofit. I've seen many and they pack quite a punch for the watts used. Make sure what you use are damp location rated or better.

RE what steve says... yes.. the electric co can come in and put a voltage meter on the house line to track the voltage level over a couple of days on a graph. Keep in mind, however, that a 10 volt surge or fluctuation on the line voltage side, only results in a 1 volt differential on the 12 volt side.

How long are those wire runs? what is the total wattage on each of the runs? With load, those lamp readings are where they are. If you were to take one lamp off line, see what the voltage jumps up to. If you have 35-36 watt PAR's, I'll bet the reading will go up at least a volt. What this means, is that as soon as one lamp burns out, the delivered voltage to the rest of the lamps increases and so on. You might be better served to drop the taps down to 12 volts, or at least on the line with the PAR's. You could rewire a home run that feeds the 3 par lamps and drop the tap down is one other suggestion I'd offer.

GOod luck.. let me know how you make out

George