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Old 11-13-2020, 02:40 PM   #1
Brand: Thor Motor Coach
Model: 2018 Siesta 24ST
State: Ohio
Posts: 96
THOR #15089
Check your high - amperage cables !!

Last weekend we were boondocking, inverter on, watching TV and waiting for the coffee maker to finish brewing, when all 120AC power went off. I checked the inverter remote panel and it said "fault". Tried to reset it, and it went to fault again. And we smelled what seemed like burning plastic.

On examining the inverter in the basement, I found the plastic housing on the 200A fuse completely melted, and the incoming plus cable insulation scorched. The fuse never blew. Turns out the incoming cable to the fuse had an improperly attached ring terminal, so that only 20% or less of the copper strands were actually making good contact with the terminal. The fuse didn't blow because the problem wasn't amperage or a short circuit, it was heat.
The cable was 4 AWG to start with (I've now replaced it with 2AWG even though it's only 3 feet to the batteries), so with less than 20% connection, it was creating intense heat as if I was trying to run 1200 watts through a small gauge wire.

You might think that buying cable with the ring terminals already attached would assure you have a good connection. Also, the heat shrink insulation (which burned up) disguised the inadequate attachment.

This could have been a full blown disaster if the intense heat had ignited anything flammable near to the cable. Don't assume your cables are good just because they are the right gauge. Check out the connections !!

steve2777 is offline   Reply With Quote
Old 11-13-2020, 03:17 PM   #2
Senior Member
Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
Posts: 894
THOR #20289
In addition to the bad crimp, which I agree was the reason for overheating, #4 gauge wire with normal insulation is only good for 160 amps. That installation should have had a 150A fuse or #2 gauge as you later installed.

DavidEM is offline   Reply With Quote

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