Fire in electrical compartment

[CaptBill]

Glad you're ok, and the motorhome can be repaired.

Looking at the photo, I can see a spiral area meltdown of the cord's outer jacket, which indicates that just under that outer jacket is a conductor that efectively became a toaster element. In order for that to happen, it seems it would be a backfeed of power into the cord (inverter?), from the transfer switch, shorting to the ground wire, more than likely, at the 30A adapter. Please let us know.

Once again; glad you are ok.

[LizCarmel]

Originally Posted by CaptBill

Please let us know.

Will do. I should know something on Monday.

Liz

[RoamingGnome]

Originally Posted by LizCarmel

I will post what they find out. It's in the shop.

Liz

Attachment 49434

What I see in the photo is that the ground pin area of the 50A plug looks the most heat damaged and as someone else noted the spiral-wound ground conductor melted its way up the cord. It also appears to me that the 15A socket on the wall behind the melted plug has significant heat damage at the top of its faceplate and the metal plate that the socket is mounted on possibly has spark damage in the same area as the melted faceplate. Based on this I would venture to guess that somehow the metal plate that the 15A socket is mounted to is energized by 115v, possibly because a wire disconnected from the socket and contacted the metal plate on the backside, and the ground pin of the 50A powercord rested up against the energised metal plate. Perhaps the 15A socket is powered by the inverter. If the metal plate was not grounded like it should have been then the ground conductor of the 50A power cord became the return path when they came in contact with each other. I'm just thinking out loud here ...

[wa8yxm]

There is no way at all a 50 amp cord should do that when plugged into 30 amps. Not even if you plug in in to to two 30 30 amp sockets using a cheater box. (I double typed on purpose) since 60 amps is not that far removed from 50. (20%)

HOWEVER.... Many RVers have a few screws loose. and I'll bet you were one of 'em.. The screw that attches to the end of that cord to the transfer switch is my guess. (at least one of 'em)

[LizCarmel]

Thanks for the info.

[palehorse89]

It is really hard to believe that even if it was warm or hot when unplugged and coiled up for storage that it continued to build enough heat to do this to that size of cord.
Wow! to say the least, I am sure glad you are OK and your Coach was not a total loss.

[Mr_D]

Originally Posted by LizCarmel

Thanks for the info.

Attachment 49517



Attachment 49518

I see that the cover is off the electrical components above the cord end. Was that cover in place and it melted too or is the cover missing? If missing it's possible for the plug end to have come in contact with the hot leads there and then melt the cord enough to fall out of contact.

[gemini5362]

Originally Posted by Dr4Film

Liz,

Your first clue to a problem was the cord feeling warm when you stored it into your compartment. The damage had already started internally and it continued.

You are very fortunate to have not had a large fire as a result.

Things to have checked are the Dog-Bone adapter, the 50 amp cord, the TRC Surge Protector and Transfer Switch.

There was obviously way too many amps being drawn through the shore power supply cable, etc.

You dodged a bullet this time. When using Dog-Bones always check them often for warmth and problems. Also, when using a 50 amp coach on a 30 amp shore power supply, pay VERY close attention to the amount of amps you are drawing at any given time.

If you have a Load Shedding device usually that will take care of the task for you.

Dr4Film ----- Richard

I Hope that when the OP finds the problem he will tell us. The one thing I am sure of is that it will not be because he pulled too many amps through the cord. Each leg of that cord is capable of 50 amps. When he pulled over 30 amps for a short period of time he would have tripped the breaker before he started damaging the cord.

[94-Newmar]

I see a 50amp to 30 amp step-down (with a 15amp reducer in the end) under the whole mess running from left to right. I see a 30amp to 15amp step down on the left side, and it appears the shore cord 50amp end is positioned vertically against the back wall on the right side. In my KS that rear 15amp outlet and 15amp plug you see goes directly to the engine block heater. I'm wondering if that is true in this model DS too? Due to the melted mass right there it certainly seems that whatever is plugged into that outlet may have been the culprit, based upon what I can see in these pictures.

[Dr4Film]

Originally Posted by Mr_D

I see that the cover is off the electrical components above the cord end. Was that cover in place and it melted too or is the cover missing? If missing it's possible for the plug end to have come in contact with the hot leads there and then melt the cord enough to fall out of contact.

I am having a hard time seeing any device in either photo that doesn't have a cover. Please help direct me to your observation. Thanks!

Originally Posted by 94-Newmar

In my KS that rear 15amp outlet and 15amp plug you see goes directly to the engine block heater. I'm wondering if that is true in this model DS too? Due to the melted mass right there it certainly seems that whatever is plugged into that outlet may have been the culprit, based upon what I can see in these pictures.

If that outlet does go to the engine block heater it would have no power to it once the shore power has been severed. If it is NOT the engine block heater but something else possibly driven by the inverter AND the inverter was on at the time, that could be one possibility suggested by a previous poster.

When I look at the photos the mass of damage is by the input side of the TRC Surge Protector. Personally, I don't like the any of the TRC products and would recommend the Progressive Industries HW-50C EMS System for a replacement.

I am only guessing in what my thoughts are and prefer to wait until I hear from the OP as to what the actual cause for this accident.

Dr4Film ----- Richard

[focker]

Originally Posted by Dr4Film

I am having a hard time seeing any device in either photo that doesn't have a cover. Please help direct me to your observation. Thanks!

Ditto on that, I can't see anything that doesn't have a cover. I was wondering if Mr_D didn't realize the clear cover was indeed a cover but I was going to ask that someone post the photo with an arrow to the uncovered device.

[Iwillbeit]

I am going to throw out my best guess based on the pictures and your description of what happened. I believe the cord had a broken wired or two causing excessive heat while you were plugged in. The burning inside the cord led to it being hot when you disconnected it. Rolling it up cause a direct short due to the insulators being burned. The constant voltage variations took its toll on the transfer switch/converter and caused it to malfunction at stick. This caused direct 12 volt current to be fed back to the cord from the house batteries down the already shorted power cable ..and yes the house batteries are more that strong enough to fry that cable.. I know it sounds like the perfect storm, but that's my educated guess and the only reasonable conclusion I can come up with for a burning unplugged power cord.

Randy

[palehorse89]

Hi Randy, I am reading and wondering how the 12VDC can backfeed into the 120VAC system and do this damage?

[Hooligan]

Is the surge guard before the transfer switch? ? If the surge guard is hot all the time, the ground pin on the power cord have gone under the edge of the surge guard and contacted one of the power wires....
(electricity had to come from and to somewhere???