Burned 110v wires on my Parallax 7300 power supply

[114FLHXS]

I have a question about my Parallax 7300 power supply in my 2001 Coucourse. The 110V wires on the bus bar next to the breakers are burnt. Does anyone have an educated clue as to why this might have occured? Thanks!

[Manitou]

Burnt wires in general is a bad connection no? Have you tried removing one and having a look at the end and the screw? Seems odd.

[114FLHXS]

Possibly poor connections or maybe even a 30a connection in a 50a box. Still looking at the problem.

[chin_k]

I don't think 30A connection in a 50A box will case that problem. I am with Manitou and think that it is poor connection between the wires and the bus bar. Each of the screws need to be torqued to a specific amount, because if not torqued correctly, it will cause loose connection and increased resistance, sparking and heat. I would replace the damaged wires, and inspect each connection to ensure there is no oxide and replace the bar and screws if necessary. Then I will put the wire torqued according the the specification.

[Scott]

It's strange to me that they'd all be subjected to the exact same condition that would result in that type of (fairly) equal charring, Hmm.

From the photo, it looks like you have decent service loops in those neutral wires (plus whatever is behind the box). Replacing the whole Romex cables would be a huge PITA and I don't advise it. Just pull them from the bus, clip and strip them back to the un burned insulation, and reinstall. Tighten them well, and check your breakers' connections for tightness as well; those frequently go loose. IT's not that they need to be super tight, it's that they need to be re-tightened later, especially after years on the road. This "might" not happen again. Keep that steel service panel on whenever these connections are live! Also keep in mind that we're looking at residential-style solid-core wires here, not really intended for mobile use. A lot of things are far from ideal here, but as usual in RV land, it works well enough in most cases.

I wonder if at some point the rig was connected to a power pole with reversed polarity. This is a mystery.

Please let us know whatever you find out, and how you go about the repair. I'm sure the screws are loose, but how loose .... ?

[JabberBox]

Check all of your ground connections, remove the cover from the transfer switch box and check the connections for your shore power cord. It connects inside of the transfer switch. Highly likely you will find a loose connection imo. Another way to tell if you possibly have a loose ground is by plugging into shore power, if the cords getting hot somethings wrong. Course i wouldnt recommend plugging yours in until you sort out the problem at this point.

[chin_k]

Definitely a loose connection that cause the heat that melt the coating on the wires. Ditto that you should sort this out before using the rig as JabberBox said. I used a thermo camera for this sort of things. It will certainly light up the area inside the panel that is not properly tightened. I am not too sure if it is from the ground, however. For AC, the return path is via the neutral wire (which are all burnt), and the ground is there for safety, and there should be little, if any electricity going thru the green wiring. You do need some clean up there with the rust/oxidization, since a safe AC connection can't be like this.

Solid wire, like Scott said is for residential use. For rig, it is better to use stranded wire because they can handle the vibration better. (It amuses me that stranded wire for mobile application, but maybe it is what is called a pun?) The hex screws on the bus bar probably got loose and oxidized due to heat.

I can see exposed copper wiring on the break side. That is another bad sign. Someone had done some work on it, and probably never check the torque on the bolts. Sorry that you end up with the mess and need to do the clean up. Good luck.

[68camaro]

I don't think 30A connection in a 50A box will case that problem.

I agree, sadly I know because when electrician installed a 30v receptacle in garage he mistakenly put in 50v and when we plugged into RV we heard a loud pop. It fried the Power Station but wires did not burn like this.

[chin_k]

68camaro, it has been a while, and my memory often fails me, but if I remember correctly, it was the electrician who was not familiar with the TT-30 connector, and put 240V on your 30A connection, correct?

[68camaro]

68camaro, it has been a while, and my memory often fails me, but if I remember correctly, it was the electrician who was not familiar with the TT-30 connector, and put 240V on your 30A connection, correct?

Correct, I never thought of using my surge protector as insurance to make sure all was good. I also did not make a big deal of it or called his company as I didn't want to see him in trouble. As soon as I got new one he came right over and installed. Alls well that end well.