Power Cord Fire

[rvrev2]

Had my 21 year old Jayco parked in my driveway and hooked up to my 30 AMP outlet on the garage. I used an RV 30 amp extension cord which is just 6 months old to span the distance from the rig to the outlet. I had the fiver hooked up for 4 days this way with the AC and fridge running with no problems. It was 104 degrees according to the bank sign while I was inside the fiver. Next thing I know, the AC starts to sound funny. Then I heard electrical buzzing from outside. I raced outside to see the electrical cord on fire where the RV cord plugged into the RV extension cord. I unplugged from the garage outlet, but the cord kept burning. It finally went out.

Some things to note:
1. I didn't have a single breaker go off. Not in the house and not in the fiver.
2. Plug from the RV extension cord going into the garage outlet showed absolutely no sign of burning or arcing. It was pristine.
3. I removed the RV cord where it was hard-wired into the RV. Once again, no sign of burning or arcing.

I won't get a replacement RV cord until tomorrow night, so I won't know if I have any damage to the fiver until then.

I'll try to attach a picture of the remains. The first photo shows both ends of the extension cord. The second photo shows both ends of the RV's cord. The third picture shows both cords side by side.

[mike837go]

The connection between the extension cord and the RV's cord is were things started. That connection got overwarm and then started arcing.

You noticed it at stage half and shut things down before any serious damage occurred.

Quick thinking and fast action!

[RedHorse1]

Wow, that's ugly. Glad to hear no serious damage and it's fixable. You think the TT cord was past its prime?

[Buckeye Hunter]

Wow, lucky you were there.

[NDJollyMon]

Wow...the things that can happen. Thanks for sharing.

[Filthy-Beast]

Glad you caught it in time.

It's important to keep the contacts of both the male and female clean and corrosion free. corrosion or loose connection in the plug or loose connection between the male and female plug will lead to over heating.

All of these scenarios reduce the connection contact surface area and would be equal to running high amps through a small wire.

I always check the CG pedestal contacts to make sure they are not corroded. I've seen corroded post contacts cause this to multiple trailer plugs. I also carry contact cleaner in case I have no choice.

EDIT: Also be very leery if your plug feels loose when you plug it in, odds are you don't have a solid connection.

[buckeyejim]

We did not have a fire, but our plug gets very hot when, ac, Refg. & Water Heater are on. To help reduce the load on hot days, I switch the water heater & Refg to Gas. The plug on the Rv cord gets warm but not hot. I agree keep the contact clean, and test the outlet for a tight fit. I have had to replace the male end of the cord, due to burnt terminals. Good to watch cord @ every campsite.

Happy Camping
Buckeyejim
Columbus OH
2011 Eagle

[33 RLDS]

Even though we all use extension cords at one time or a another, I guess this is why the owners manual says to not use them.

[Filthy-Beast]

Good contacts, no loose connections and extension cords with the proper gauge wire for the amperage flowing are not a problem. The issues I've seen like this with poor pedestals were all without an extension.

[TWP723]

Good night!!! Glad you caught it in time and no one was injured!

[VicS1950]

Not that anyone asked...

Originally Posted by rvrev2

...

Some things to note:
1. I didn't have a single breaker go off. Not in the house and not in the fiver.
2. Plug from the RV extension cord going into the garage outlet showed absolutely no sign of burning or arcing. It was pristine.
3. I removed the RV cord where it was hard-wired into the RV. Once again, no sign of burning or arcing.

...

As was stated already, the problems relate to the overheated plug connection. The high ambient temperatures and a black colored cord in the sun contributes to overheat issues. As that connection deteriorated the resistance increased which reduced the system voltage to those fairly high load appliances.

The reduced voltage caused increased amperage which is why you noticed the change in operating noises. The voltage lowered and current increased, but the current didn't go high enough to trip any breakers. That is why nothing tripped.

Had the fire continued long enough the insulation between the current carrying conductors, or the ground would have likely broken down to a dead short which would have eventually tripped the pedestal breaker. Given the failure details I would not expect the RV breaker to trip.

The fire which started in the plastic/cord would have continued to burn even with the power off, but with the proper UL approved insulation should burn itself out over a short time once the heat source is removed (breaker tripped).

Originally Posted by Filthy-Beast

Good contacts, no loose connections and extension cords with the proper gauge wire for the amperage flowing are not a problem. The issues I've seen like this with poor pedestals were all without an extension.

I agree.

It is important to periodically clean the male plug blades with a medium aggressive Scotchbrite or scrubby pad to help keep the prongs conducting properly. A light coating of Vaseline or contact grease helps keep corrosion to a minimum. The grease also helps to preserve the receptacle contacts which are difficult to access and clean.

It is a good idea to remove and re-install a semi-permanent plug periodically for inspection and cleaning. R&R of those plugs "wipes" the receptacle contacts which helps with cleaning and will most times change the points of contact in the receptacle when re-inserted. Those are all good things.

Unfortunately many campground receptacle contacts degrade over time. There is little you can do to help that situation, but you can feel your connection plug occasionally to make certain it is not getting extremely hot. A spritz of WD-40 into the pedestal receptacle (with the breaker off) might help with corrosion. It can't really hurt anything.

Being that the equipment was shut down almost immediately I would expect that your RV is ok.

FWIW. vic

[rvrev2]

thank you all for the encouraging words. The RV Cord is supposed to arrive tonight. I hope so, because I want to install it and check things out to ensure there is no damage.

Also, thank you all for the ideas on keeping contacts clean and maintenance.

[silverark]

I would use some dielectric grease. Auto parts store sells it. The heat buildup is caused by resistance due to corrosion of the plug ends. it doesn't take much corrosion to cause a problem. Another tip is to use the grease on your 7 pin plug to keep it in good condition. This can cause some braking problems with electric brakes.


http://www.permatex.com/products-2/p...-grease-detail

[BJR]

Originally Posted by silverark

I would use some dielectric grease. Auto parts store sells it. The heat buildup is caused by resistance due to corrosion of the plug ends. it doesn't take much corrosion to cause a problem. Another tip is to use the grease on your 7 pin plug to keep it in good condition. This can cause some braking problems with electric brakes.


Electrical System Maintenance : Permatex® Dielectric Tune-Up Grease

Keep in mind dielectric grease can be an insulator. I wouldn't use it too liberally on contacts.

[mike837go]

Originally Posted by BJR

Keep in mind dielectric grease can be an insulator. I wouldn't use it too liberally on contacts.

The act of making the connection wipes the grease from the metal parts.

"Just enough to coat" is the instructions on the package, if I recall...

[Filthy-Beast]

By sanding( using an abrasive) you create less contact surface and it should not be done on contacts in good shape. However if badly corroded or oxidized it will increase surface area.

This is made specifically to clean contacts, even oxidized ones. I carry a bottle of the 100% solution of Deoxit D, This also works great for cleaning battery contacts in remotes and stuff that have had a battery leak or corrosion on the contacts. For other applications where reducing voltage drop is important I also use Deoxit Sheild and Deoxit gold.

Amazon.com: CAIG DeOxIT D100 Power Booster Metal Electric Connection Cleaner, Enhancer, and Lubricant: Electronics


Data sheet
https://system.netsuite.com/core/med...&cktime=131820

[RACarvalho]

This may happen when the contact of the pin is not strong.
If the contact between two metallic parts have too little area, the current is forced to pass through that and this condition generate heat.
you don't need to trip the 30 amp shunt/fuse, you just need to reduce the contact area enough so the resistance to the current increase and heat is generated.
That is the reason the shunt/fuse didn't trip (better check though).
It's the same principle used on those robots that are welding car body parts on assembly lines.... The heat from the resistance on the contact of the two metal sheets melts the spot and they are "welded" together....

[VicS1950]

Originally Posted by Filthy-Beast

By sanding( using an abrasive) ...

We seem to disagree on some things.

I specifically mentioned a medium Scotchbrite or scrubby pad, not sandpaper. It would take a real effort on the part of a determined individual using a scrubby pad to significantly reduce the overall size of a contact prong to the point of affecting conduction. Less effort with sandpaper, but even then the person would still need to be somewhat determined.

Not many will take the time to purchase and use specific products to prepare for the task.

Many people will actually follow up and clean their plug ends with commonly available items like scrubby pads and Vaseline. Clean is better than unseen and corroded over time. Maintenance with common items will improve their situation.

Receptacle contact clamping force is certainly a factor. There are test methods for verifying proper receptacle clamping forces. Again, who is going to purchase such testing equipment? I personally believe staying with more basic practical methods has a better chance of success.

vic

[Filthy-Beast]

Originally Posted by VicS1950

We seem to disagree on some things.

Sorry if you took it personally, I did not quote you or call you out. I said sanding, specifically because many people will use sand paper or even nail files, the micro scratches created by abrasives do reduce surface contact area, increasing voltage drop, raising temps. I also said that doing it on contacts in good condition was not a good idea but would help older corroded contacts.

Using a white eraser from and ink pen to clean good contacts would be better.

[rvrev2]

Good news. New cord arrived. I installed it and nothing appears to be damaged on the rv.