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Joined: Jan 2004
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I checked the voltage at the panel. The customer has changed the bulb a couple times and it still does it. I didn't get any complaints about lights getting brighter but they do dim when A/C starts.
I'm not sure of the transformer kva. However, the meter/main (200 amp) disconnect is approx. 180 feet from transformer. Then about another 60 feet the the house distribution panel (also 200 amp). The pole barn also taps from the main panel and travels about 200-250 feet to the pole barn. This is #2 aluminum wire feeeding a 100 amp loadcenter with very little load.
This problem just started within the last few months. Makes me think it is a PoCo issue ahead of meter.
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Joined: Apr 2002
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There could be a lot of contributing factors, POCO loads on the transmission lines, Vd in the customer owned service feeder and sub-feeders, and the branch circuit.
Vd calcs for the above for starters. Thorough recording of events (Voltage and amperage) at main and sub panel(s) will give more details. You have 500' +/- of conductors. Also, the AC unit may be starting to have issues.
One side ? for my curious mind....AC on at this time of year?
The amount of time that would be required to do what I suggest, vs. the swap to 230/240 volt fixture may take care of the HPS light issue.
Good Luck
John
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Joined: Jul 2004
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You really need to hang a power line monitor on the service if you want to start pointing fingers at the PoCo. I have done it but they usually deny a problem until you show them the tape and they still try to say that is within the nominal tolerance if they can.
Greg Fretwell
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Joined: Apr 2002
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IMHO, someone has to draw a line on how much $$$ to spend, IF the only issue is the HPS fixture.
John
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Joined: Jul 2004
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It's too bad Merlin is so far away. I would loan him my Dranitz.
Greg Fretwell
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I thought we had an underground problem. So, I done a fault locate and found 2 spots with leakage to earth. I dug them up only to find minor nicks in the cable and fixed them. After further investigation and watching voltages and current on cables, I think it is just a case of voltage drop.
I got out my measuring wheel and determined it is 400+ feet from main distribution panel to building with the issue. I decided plug all the information into my electri-calc. With the 400', #2 AL, 121 volts, and 11 amps....it tells me that i have a VD of like 4.4 volts. That is about what I'm seeing.
BUT, I still don't understand why equipment in the house is affecting the light in this building. The voltage drop is on the service wire feeding the building only. No effect on the main panel. And there is no other load on in this building at night when the light is on.
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Joined: Apr 2002
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Merlin:
Did you check the voltage at the source of this 'feeder', and see IF it varies.
Anything cycling to affect the load, like the HPS variation in startup and full luminance?
John
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Joined: Jun 2004
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The repaired conductor must be Megged.
Aluminum is at extreme hazard when in contact with the earth.
It corrodes ENDLESSLY in the presence of chlorides. ( table salt )
Unless you used epoxy encapsulation -- you shouldn't trust your underground repair.
The light is controlled by a photo-eye. That's what's dropping out the lamp. It can change its logical state in microseconds. Ordinary field test equipment is not going to spot that.
Tesla
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Joined: Jan 2004
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An issue still continues with this service. I followed some advice (and my gut feeling). I decided to change the fixture over to 240 volts. This required changing the fixture ballast, photo-eye, and some minor rewiring. And after all that.....the problem still occurs! When a heavy load starts, the light goes out. Any more ideas aside from replacing 425 foot of URD all for a simple light?
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Joined: Jul 2007
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You mentioned earlier that the lights dim win the AC compressor kicks on. It still sounds like a voltage drop issue. If you can and have a voltage recorder of a max/min setting on your meter, I'd track the voltage as close as possible to the light.
Can you guesstimate the wire size of the utility's triplex? I remembered doing a service upgrade one time and the old service had #6 or possibly #8. It was and old 60 amp service put in a 200 amp service. The poco showed up and just reconnected the existing service drop
?=^P
"Live Awesome!" - Kevin Carosa
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