2018 Torque T322 Electrical Problems

[renerod1969]

So last weekend I took the toy hauler out and was running my A/C, next thing I know, no AC power from Gen, figured the transfer switch went out, gen was still running strong, only has 35 hours on it, replaced the switch today and still nothing. Figured I better trace power from Gen to the transfer switch, I found a junction box in the storage unit, after crawling my fat *** in there and taking the cover off I smelt melted wires right away. attached are pictures of the wires, wire nut was melted completely and it never trip the breaker on the Gen or on the panel.

My questions are, Would a loose connection and arcing cause this? Why didn't it trip a breaker?

Its working now that I cut off that melted wires and wired back up but I am concerned that it might happen again and I wont be so lucky.

Onan 4000 Gen

 

[danemayer]

Here's my guess:

• Poor connection at the wire nut.
• Resistance gradually increased.
• Increased resistance caused the wire to get hot.
• Electric demand from the A/C plus heating the wire raised the amperage demand on the generator, but did not exceed the generator breaker rating.
• Eventually the wire connection got so bad that the transfer switch wasn't seeing 105V on L1, and it shut down.
• If the wires that overheated didn't come into contact with a ground, there would be no short circuit to trip the generator breaker.
• The metal junction box contained the overheated wires, preventing damage outside the box.

 

[renerod1969]

Here's my guess:

• Poor connection at the wire nut.
• Resistance gradually increased.
• Increased resistance caused the wire to get hot.
• Electric demand from the A/C plus heating the wire raised the amperage demand on the generator, but did not exceed the generator breaker rating.
• Eventually the wire connection got so bad that the transfer switch wasn't seeing 105V on L1, and it shut down.
• If the wires that overheated didn't come into contact with a ground, there would be no short circuit to trip the generator breaker.
• The metal junction box contained the overheated wires, preventing damage outside the box.

Should I be concerned? I replaced all the bad wire and made sure the connection was good. Would it be wise to maybe put a breaker or even a fuse at that connection?
The wire from the gen to the junction box is stranded, from there it is romex to the xfer switch.

 

[danemayer]

Should I be concerned? I replaced all the bad wire and made sure the connection was good. Would it be wise to maybe put a breaker or even a fuse at that connection?
The wire from the gen to the junction box is stranded, from there it is romex to the xfer switch.

It can be hard to get a good join of stranded and solid wires. I like Wago connectors (hat tip to Jesstalkn). Each wire is clamped by its own lever so it does a great job with different wire types and different wire sizes. Here are some rated at 30 amps/300V and handle up to 10awg wire. They'll work unless you have some 6 or 8awg in there, in which case you might look for larger ones.