Sudden problem developed that I need some basic advice on. Symptom is: lights dim slightly for 3 – 4 seconds, then come back up to normal. Seems to happen on a regular cycle…2-3 minutes normal, the 3-4 second dim, 2-3 minutes normal…etc etc. Not associated with any other appliances kicking on or off, but does seem to dim more when the electric dryer is running.
What kind of trouble shooting should I do? I’m comfortable working in panels and subpanels, but don’t own testing equipment beyong current probe and three prong circuit tester.
This was an inspected DIY job I did myself 8 years ago…this is the first problem of any sort.
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All the lights in the house? On one or a few breakers? Does the dryer vent go anywhere near the breaker box? For any appliances that you can hear when they are running, do you hear the motors slow down when the lights dim?
It sounds to me like an arc fault. It arcs for 2 - 3 seconds, which heats the wire until it flexes enough to cure the arc. Hard to know if it opens when it heats up or closes.
Seems to be confined to an addition with its own subpanel, which also runs the washer, dryer, fridge and freezer. Any or all of these applicances running or not running don't affect the dimming.
Guess I'll have to dedicate some time to isolating circuits to see if any one circuit has a problem, then go through the boxes one by one, checking connections.
I would start with the main pannel. Check the connections on the feed breaker, neutral and ground.
Then do like wise on all of the connects on the sub-pannel.
If it seems like all the lights in the house are doing this then likely it's line voltage variations on the incoming power.
I've noticed the same thing around here in the early AM as loads are coming on-line -- the stepping transformers that control line voltage keep adjusting themselves, trying to keep up with the rapidly changing load.