Why didn't the breaker trip ?

Old 02-17-13, 09:40 AM
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Why didn't the breaker trip ?

I'm trying to understand why a breaker did not trip. If this needs to be moved to a different section, please do so mods.

House built in 1964. Copper wiring. We bought the place in 2005. Breaker box is a Federal Pacific Electric Stab-Lok (Catalog 108-16). The breaker in question has a "20" marked on it. It controls the home office and a guest
bedroom. In the home office, that light fixture has always burnt out bulbs fairly common.

8th - lost power to the home office. The overhead 2 bulb light fixture not coming on. No power from outlets. Breaker was not tripped. After my wife reset a few times it came back.
14th - bulb blew. Decided to deal with it in the a.m.
15th - lost power again. I turned off the the breaker. Decided to inspect the wall switch that controlled the overhead light. I noticed paint on the light switch. When the former owner painted the room, I'm guessing he'd left the wall cover off the switch. I decided to replace the switch. After doing so, everything came back. Until late that night, when we lost power to the office again.
16th - turned the breaker off. I decided to inspect that overhead light. I noticed that the one bulb socket had a little corrosion. When I removed the fixutre, I found the red wire nut on the white wire had a black discoloration. It'd also split. Please see attached picture.

In thinking back, I do recall putting 75w bulbs into the fixture sometimes. So that was extra heat. At this time, I've replaced it with another two bulb fixture. I've got 2 60 w CFL equivalent bulbs in there at this time.

Things seem to be resolved.

Was the fixture overheating and the split wire nut put it over the top ? Also, how come the breaker did not trip ?

Any insight would be appreciated.
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Old 02-17-13, 09:49 AM
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The breaker will trip on a dead short or a continuous overload. I don't think either was present in your issue there.

However..... Federal Pacific breakers have proven themselves as being completely undependable and in some cases down right dangerous when they don't trip when they are supposed to.

Is My Electrical Panel Safe? - Important Information About Federal Pacific Electric, Zinsco and Outdated Electric Panel Boxes
Old 02-17-13, 10:22 AM
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While using higher wattage bulbs than you are supposed to is a problem, I don't know if that caused your wire nut to split. My guess is that the wire nut may have been damaged from the beginning and over time opened up and allowed the connection to come loose.

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