Lighting Circuit


Old 09-07-00, 10:54 PM
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I have a 6 light circuit in the lobby of my workplace controlled by a regular light switch. For the 7 years since the building was open the lights have worked fine, but for the past 3 months the bulbs burn out way too fast. Now, all but one burn out as soon as they are put in. This morning I tested the voltage at two of the light sockets and it was 230 instead of 120. What could possibly have allowed the voltage at the light sockets to have gotten so high? Can a circuit breaker allow excess voltage if it goes bad? What else can I test?
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Old 09-08-00, 05:51 AM
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sounds like you may have lost the neutral or the grounded conductor. check other circuits and see if you get a real low voltage reading on any of them.GO to your main panel and check to see if you have 120 volts on each leg coming in if one is way high then call the utility company if they are the same then you will have to start looking for something that has came loose in your wiring system most likely it will be a white wire loose some where
Old 09-08-00, 07:05 AM
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This can also happen on shared-neutral circuits when someone removes an outlet.
Old 09-08-00, 02:45 PM
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The loose neutral is a good suggestion. I take it that we are talking about incandescent bulbs. Not flourescent. If you have regular incandescent bulbs then the loose connection, most likely a neutral or grounded conductor is the culprit. Neutrals and grounded legs are notorious for causing the voltage to raise.

I got an idea out of left field. You are quoting a voltage on a single phase system matching what is expected for a double pole breaker. Have you tested this voltage several times and found the voltage to be 230 volts each time. If so, I suspect wiring has been worked on sometime in the past and either a white wire has been connected to the other hot phase by mistake or you may have had a service upgrade and the electrician may have missed read the circuit and put you on a double pole breaker.

Check your voltage at the socket several times. If the voltage is the same each time, then somewhere their is a connection made by mistake to another hot phase.

If this is a commercial building and the sockets you are talking of are on a set of flourescent fixtures then I suspect that you may have a 277 volt 3 phase lighting circuit.
Check you light panel and see if it is 3 phase rated. If this circuit is a circuit coming from a 3 phase panel. Your voltage at the light would be expected to be 277 volts. If you are using a light up style tester you would not see any difference between a 230 volt reading and a 277 volt reading.

Good luck.

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