All wires on bus bar fried at same time

[pachudzik]

Hello, all!

Just got my first Toy home, a 1991 Warrior 321RB.  Everything was working great until today:

 

Connected to shore power, I turned on the air conditioner on High Cool and within a minute smelled cooking wires. When I opened the panel below the sofa-bed, I found all the wires connected to the bus bar are equally fried and the breakers had not tripped at all (See photo attached). The only other electrical draw was coming from the stock Dometic fridge on a low thermostat setting. I have been using this set-up for several weeks with no problems, so why all of a sudden?  Any thoughts on what caused this?

Thanks in advance!

 

 

Edited June 17, 2019 by pachudzik

[fred heath]

Check the neutral connections for your AC. A loose connection arcing across the line voltage would cause this problem. 

Locate and isolate the wires (Romex?) from the A/C and the panel.Do a continuity check for both the black and white wires. With your tester on either white or black probe both wires you should only get continuity on the wire you’re attached to. If both, you’ve got wires touching somewhere. (Mice maybe?).

After thought. Are your 12V wires and 120v wires maybe crossed?

Edited June 17, 2019 by fred heath

[Maineah]

You got some serious smoke there tell me about you power cord? Does it have a replacement end?

[Maineah]

I had another look at you mess. Due to the corrosion on the large white wire I believe this has been going on for awhile the load on the white wire was a high resistance fault such as a loose screw it in turn cause the entire buss bar to get hot, really hot. The buss is a floating neutral the black plastic thing behind the buss keeps it from contacting the case of the load center most of it is pretty cooked more so where the large white wire is landed.  The use of high demand things like a microwave and or the AC will cause overheating of a poor connection this kind of load is like a high resistance load from space heater. This is not from a short circuit otherwise it would have tripped a breaker either in the camper or the city outlet it was connected to. There really is only one fix replace the load center and cut back/replace the wires that were over heated. This kind of fault is why we are now pledged with arc fault breakers this is the kind of thing that sets fire to houses.

[pachudzik]

Maineah, You are correct! I believe this was a long time in the making. That large, multi-strand white wire was only hanging on by 3 hairs. 

 

Per a friend's suggestion, I cleaned up the bus bar, clipped the wires back to fresh copper and reconnected them with dielectric grease and everything works great again. 

 

I just left the bus bar "floating" by the wires in the box since that plastic piece was too fried to put back. Any issues with leaving it that way?

 

Thanks everyone for your responses. 

[Maineah]

OK here is the deal your RV panel is what is called a sub panel a sub panel is wired differently than a normal panel it's white wires (neutral) are not grounded unlike a house this is a safety precaution so it can't touch and thing that is grounded or the protection would become mute. They do sell the buss bars at big box stores in various lengths I would replace it they are cheap it's been cooked pretty good.  One work around would be nylon screws and nuts with a plastic/phenolic backing and re bolt it to the panel  just letting it hang my not be the best bet. One of the best dielectrics is Noalox it also is used with dissimilar metals copper/aluminum.