50 Amp power cable fire

[Munson]

Currently own a 2020 Sierra 379FLOK , power cable just exploded at the post end. Blew a pencil size hole out the back of the plug right at the location of one of the blue led lights that indicate power is on. Caught on fire, luckily we were here and I turned off the power quickly. Anyone else had this issue?

[Bama Rambler]

Plug end failures happen once in a while. It sounds like there was a loose connection in the plug and that created a lot of heat that melted the plastic. I'd like to see a picture of it if you have one.

You can replace just the plug or the entire cordset.

[Munson]

. Already put a new head on. Back in business

[n1acguy]

Can't see it too clearly, but it looks like the prongs got real hot. That usually happens due to a bad connection.

For myself, if the plug doesn't fit snug due to a worn receptacle, I'll use an adapter to plug into the 50A.
Since you need the 50A, if you use the 30A with an adapter you'll have to watch what you turn on.

Whichever way you need to do it, using a worn and loose receptacle will always lead to a problem eventually, so I recommend avoiding doing so even if you have to compromise.

[Munson]

Prongs were in good shape, from the box I have a voltage protector circuit which plugs into my power cord, I work maintenance at a trailer park so I’ve seen faulty connections before, my concern here is that because my power cord is less than 2 years old I’m wondering if any other people out there bought new trailers in the last couple of years have had a similar issue. This is just a badly manufactured power cord and that scares me if there’s more of them out there.

[nic7320]

Originally Posted by Munson

... I work maintenance at a trailer park so I’ve seen faulty connections before,

It could have been a manufacturing defect, but it's more likely your plug failed due to a worn out socket on the pole. As you know, the pedestals get lots of abuse, and each mating takes a little bit of the plating off the contacts. Once the resistance rises, both the socket and the plug will get very hot and something will fail, but it's not always the socket.

Unless you check your connections with an infrared camera or check it with your hand, you'll never know how hot it's getting. Add to that, the peak current draw will probably happen when you're busy doing something else.

If you're still concerned, touch your plug after your AC has been running for a while and see if it's hot.

[Bama Rambler]

Looks to me like it was a bad connection inside the molded plug. Definitely a mfg. defect.

Even though you've already replaced the end, I would contact the mfg. and send them a few pics of it.

[5picker]

Originally Posted by Bama Rambler

Looks to me like it was a bad connection inside the molded plug. Definitely a mfg. defect.

Even though you've already replaced the end, I would contact the mfg. and send them a few pics of it.

Agreed... this is good advice.

[Lee Pedrick]

That molded plug was fine. The outlet in the campground post is worn out. They should replace it for you. Always check your connections every once in a while for heat. The left side connection on the post outlet is wore out. I almost lost my $200.00 surge protector because of that same exact problem.

[5picker]

Originally Posted by Lee Pedrick

That molded plug was fine. The outlet in the campground post is worn out. They should replace it for you. Always check your connections every once in a while for heat. The left side connection on the post outlet is wore out. I almost lost my $200.00 surge protector because of that same exact problem.

I won't say for sure since we really didn't see the plug (now cut off) from the blade side but what you can see of the blade and the plastic/rubber moulded around it, the blade doesn't show the same melting as it does where the wire attached to the blade up inside the plug.

[Mike134]

Originally Posted by Lee Pedrick

That molded plug was fine. The outlet in the campground post is worn out. They should replace it for you. Always check your connections every once in a while for heat. The left side connection on the post outlet is wore out. I almost lost my $200.00 surge protector because of that same exact problem.

I will disagree. If the connection was bad at the outlet itself that would be the greatest point of heat melting the plug back from the face. He described it as melting at the back of the plug so a manufacturing defect.

[D W]

Originally Posted by nic7320

It could have been a manufacturing defect, but it's more likely your plug failed due to a worn out socket on the pole. As you know, the pedestals get lots of abuse, and each mating takes a little bit of the plating off the contacts. Once the resistance rises, both the socket and the plug will get very hot and something will fail, but it's not always the socket.

X2. I can't tell you the number of times that I've arrived at a campground and found both the 50A and the 30A receptacle circuit breakers on when I go to plug in. This tells me there's a certain mentality out there to just grab the power cord and disconnect while under load. This has a detrimental effect on the receptacles.

[Scrapper]

Originally Posted by Lee Pedrick

That molded plug was fine. The outlet in the campground post is worn out. They should replace it for you. Always check your connections every once in a while for heat. The left side connection on the post outlet is wore out. I almost lost my $200.00 surge protector because of that same exact problem.

Since you were not there how can you be so sure? When an outlet is worn out there is arcing where the prongs meet the contacts. It may show up on the prong as a discoloration if the wear is minor or pitting if the wear is more severe. Once pitting starts it always gets worse even if left plugged in. OP states that the prongs appear to be in good shape.

[nic7320]

Originally Posted by n1acguy

... For myself, if the plug doesn't fit snug due to a worn receptacle, I'll use an adapter to plug into the 50A.

Really good idea to use a 50Amp to 30Amp adapter.

[Munson]

People plugging in their trailers without checking breakers, absolutely true, another interesting point, apparently coiling your power cord as opposed to laying it out also could cause excessive heat as each coil builds upon the heat from the lower coil. Not sure if this is true but will no longer coil my power cord.

[Mike134]

Originally Posted by D W

X2. I can't tell you the number of times that I've arrived at a campground and found both the 50A and the 30A receptacle circuit breakers on when I go to plug in. This tells me there's a certain mentality out there to just grab the power cord and disconnect while under load. This has a detrimental effect on the receptacles.

I don't ever recall turning off the breaker before pulling the plug. But then again won't be any harm because there's no load. Microwave is off (wife would be upset if she was cooking something and I pulled the plug) lights off so battery doesn't run down while traveling, A/C off cause it's part of the shutdown/close up routine, so yep no need to worry no load when i break the connection. As an added benefit no load when I connect at the next stop.

[Larry-NC]

Originally Posted by Mike134

I don't ever recall turning off the breaker before pulling the plug. But then again won't be any harm because there's no load. Microwave is off (wife would be upset if she was cooking something and I pulled the plug) lights off so battery doesn't run down while traveling, A/C off cause it's part of the shutdown/close up routine, so yep no need to worry no load when i break the connection. As an added benefit no load when I connect at the next stop.

Well...the converter, maybe. I doubt that you pop the breaker for the converter every time.

The water heater, maybe. There are a lot of folks who have a propane phobia and always use electricity for it.

[formerFR]

I had this same 'melting' of the neutral connection WITHIN my coach, on the way back from Alaska, while traveling thru Montana - stopping in Missoula at a RV dealer who had an employee/tech who was nice enough to help pinpoint the issue, for a $20 bill. : )

what happened: my coach originally came with a sidewall 50amp inlet connection for the twist-lock 50amp shore cord, near the rear driver side of the coach. I never liked having to 'take out' the whole heavy shore cord in order to attach it to the coach, and then plug into the outlet at the pedestal. So, I thought, 'why not' hard-wire it directly into the point where the shore cord would enter the coach? If so, I'd only have ONE end to deal with - the 50amp MALE plug, and ONLY have to take out the amount of shore cord to reach the pedestal. Yep, since the DEF tank bay is where the inlet's shore cord wiring snakes thru and ultimately into the inside of the coach thru the bottom of the master bed 'frame', it became evident that this was something that was easily possible - actually, I don't know why the factory doesn't do this as a typical shore cord wiring, anyway.

So, I pulled the coach's external 50amp inlet cover. Easy enough. After removing the wiring from the inlet's plug, it was then easy enough to pull it back out thru the DEF bay, leaving me an 'extra' 6' of shore cord all the while.

I simply re-connected the male twist lock end, and permanently plugged in the female end of the Shore Cord. Easy modification, and now no more 'hauling out' the heavy shore cord. It simply stored while wound around the DEF tank, and it was never easier hooking up easily to shore power.


That worked just fine for many trips and miles, and to and thru Alaska, until one day when I have some issue with things working properly when on shore power. This is where Missoula MT and the nice dealer employee came into the picture. He did some sleuthing, and come to find out, the neutral connections within that twist lock male/female connection had 'burned' together, melting the surrounding twist-lock plastic as well, and creating connection issues.

I thanked him, and decided to tackle this easy job myself. While difficult, I eventually got the ends removed and was ready to re-wire these line together, removing both twist-lock connections all together.
I then simply mounted a substantial 'j-box'(junction box) on the sidewall of the DEF bay where I could then easily connect the newly removed coach-end wiring to the coach-end of the Shore Cord, after I also removed it's female twist-lock device. Easy. Yes, these are large #6 gauge wires, and yes, you need substantial sized 'wire nuts' to connect them, hence the need for a substantially sized j-box.
Now, though, the j-box is mounted within the DEF bay, on the sidewall, out of the way, and the WHOLE shore cord is easily stored while curled around the DEF tank. I've never had a problem since.

[nic7320]

Wire nuts by themselves are not allowed in RVs due to vibration issues, but they are acceptable if taped with an approved electrical tape.

[Larry-NC]

Originally Posted by nic7320

Wire nuts by themselves are not allowed in RVs due to vibration issues, but they are acceptable if taped with an approved electrical tape.

What do you recommend for connecting two large-gauge (AWG 10-8-6) stranded wires carrying 120 or 240v? Butt splice or pigtail splice?