issue with lights not coming on fully


Old 10-23-16, 10:29 PM
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issue with lights not coming on fully

My daughter is having an odd electrical problem at her home. The home was purchased earlier this year and she is doing some renovation. An electrician came in and updated the service and much of the wiring... upgraded to 200a service, ran new lines to include a ground wire, split busy circuits, etc.

Everything works fine with one problem.

On a line that has NOT been replaced (original wiring) there is a light fixture (incandescent bulb chandelier). When the light is turned on, it does not come on fully. After a minute or two, it will go to full brightness. Once at full brightness, it stays there (no flicker, doesn't dim to a lower level) and works as expected.

Any idea what would cause this?
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Old 10-23-16, 10:57 PM
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Has this one fixture always had this problem? Is this fixture located where changing the bulbs is difficult?

If the answers to the questions are yes I can think of one possible reason although it IS a long shot. In such a situation it is possible (not real likely, but possible) that the fixture has a device called a thermister installed. This device, when cold, adds resistance to the circuit with the result the lights will be dimmer. As the thermister warms the resistance becomes less allowing more voltage to reach the light bulbs. It is sometimes used in fixtures where changing bulbs is difficult to limit the voltage on the bulbs during the first few moments after turning on the switch as this is when most bulb burn-puts occur.

If I am correct then it is normal operation and implies a quality fixture. If I am not correct then I don't have a clue.
Old 10-24-16, 06:27 AM
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Is there anything else (light, receptacle) on that line? Try an incandescent bulb or fixture at that location.
Old 10-24-16, 08:08 AM
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Hard to say if it has always been a problem. They are new to the house and have been doing quite a bit of renovation. They just started using the room with the fixture.

The fixture is over the dining room table. Very accessible. I will look into the thermister idea.

I will have to go there to see, but I am sure there are other items on that circuit. Very possible that a small fluorescent light fixture in the next room. As it turns out, the fluorescent fixture is having issues with either a bad bulb or bad transformer. Could that have something to do with the problem?

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