Fire Hazard

[SteveandTerri]

Hi - Here's a copy of my post from last year. It explains the way the electric system started to misbehave and how I figured out the problem... There are pictures on the posting (link noted above).

The wife and I have been on the road in Sisters, Oregon for the last 10 days. A few days ago - all of a sudden - the TV, Microwave Oven, and Fireplace stopped working. This was the second time this had happened. The first time everything came back ON after about 20 minutes. This time the appliances didn't come back ON.....

So, I thought maybe a breaker had tripped. Checked the 5ers panel: all breakers ON... but I opened and re-closed all of them anyhow - you never know... no change: appliances still OFF. Went to the power pedestal (operating on the 50 Amp Service) and checked the breaker: it was ON but I opened and re-closed it anyhow. Still no change: appliances still off.

Went back to the 5ers panel and stared at it for a while... noted that all of the appliances that were OFF were fed by breakers on the right side of the panel. Got out the Volt Meter and started troubleshooting. First checked the Power Pedestal: 120 volts on each leg. Then went to the 5ers panel: found 120 volts on one leg and 0 volts on the other leg.

So, if there's power at the pedestal and no power at the 5ers breaker panel, the problem has to be somewhere between the two... Figured the most likely spot would be the Shore Power Inlet. First checked power at the end of the power cord: 120 volts on each leg: all good. Then noticed evidence of burning at one of the power prongs inside the Inlet Socket (see picture)... not good.

At that point I knew I had to take the Shore Power Inlet Socket out and see what was going on. Found a set screw on one of the power leg wires wasn't tight. The prong that was connected to that wire had brownish discoloration indicating arcing in the area. Next step was to take the whole assembly apart: sure enough, found the plastic around the prong had started to melt. Finally determined the root cause: one of the power leg wires had been inserted too far: the plastic insulation was partially in the clamp.

Over time, the insulation had gotten warm, deformed, and the clamp-to-wire connection loosened up. Arcing then developed and the connection failed completely. Thank goodness it didn't lead to a fire. When the Power Inlet was first installed at the factory, the technician probably tightened the terminal clamp just like the others: nice and snug.