Plugs on fire

[ITSNO60]

Originally Posted by eubank

At the RV park that we used to own, this was a constant problem. Early on, people would arrive with badly burned or corroded blades on their plugs, and stick them into our receptacles. Guess what: Next thing you know, the receptacle on our side was burned up. We finally instituted a change of procedures whereby I got a peek at every plug before it got plugged into our system. And, if need be, either cleaned up their plug (I carried a sacrifical pocket knife for that very purpose) or, in exteme cases, did not permit them to plug it in. (The extreme case was vanishingly rare.)

Of course, a regular part of maintence on both sides is to examine the system, both park side and RV side. If one of our receptacles was going down, I replaced it. It's not rocket science. And with permission, I also replaced a couple of customers' plugs at cost. Enlightened self interest.


Lynn

As a retired electrician I carry a spare plug and receptacle. If I run into a worn out receptacle I would change it with the park manager's permission but not sure if most would agree to that, none the less I'm prepared anyway.

[Flathead1984]

There are breakers in the trailer and on the post. They did not trip. Also, the fire occurred at the connection of my main power cord and an equally sized extension. The dogbone was not damaged.

The 30amp post was “old” according to maintenance staff. Breakers loose. The manager had me use my extension to reach the 50 amp outlet, which was new.

I have been in place for 2 weeks on the 50 amp circuit. I have 1 Dometic AC. Do use the electric hot water heater to save propane.. after start up, I probably draw 15 amps with both compressor and fan motor.

From the discussion, here is my best guess:

1. It was a very hot day 95+. Everyone had a/c running. Park full. There may have been a voltage drop causing increased current and heat

2, or one of the leads inside came loose. However, it must not have shorted otherwise one of the breakers would have tripped?

I went to local RV dealer and replaced the plugs with Campco version ($42 each! ). I am going to find better/heavy duty 30 amp plugs.

[az-streamer]

I wonder if this would have occurred with a surge protector in place?

Did not see one mentioned here as being used.

[John Ware]

Originally Posted by Al and Missy

The last time I looked, NFPA-70 (NEC) code requires a main breaker. I'm surprised that your trailer doesn't have one. Mine does. It is not like a home panel with the mains breaker at the top. It is one of the 6 breakers in the box and the incoming feed is connected to the load side of that breaker creating a reverse feed, which is allowed by code.

You're right. I couldn't imagine why I had no Main breaker either but I'm so used to seeing a double pole main that I forgot my trailer is 110v. I couldn't tilt my head far enough back to see the 30 with my bifocals. It's the one on top.

[Al and Missy]

Originally Posted by John Ware

You're right. I couldn't imagine why I had no Main breaker either but I'm so used to seeing a double pole main that I forgot my trailer is 110v. I couldn't tilt my head far enough back to see the 30 with my bifocals. It's the one on top.

That thing with the bifocals is going around.....

[Al and Missy]

Originally Posted by waninae39

best to clean the connection each time.
dielectric grease is also good to use.

as other have stated, dirt and loose can connection are dangerous , as resistance goes up, so does heat. best to use good quality stranded copper vs, aluminum or solid wire

also , avoid cheap products , they are not worth it

I often see recommendations for the use of dielectric grease on connectors. As a retired electrical engineer, I always wondered. By definition a dielectric is an insulator. I finally decided to look into it and this is what I found.

"Ensure that the grease does not touch the path of electrical currents or where parts are connecting. This is because the grease is an insulator, and it disrupts the flow of currents. Therefore, it is recommended to use dielectric grease on surfaces of electrical parts where the currents are not passing."

Put it on the outside of CATV connectors before sliding the covers on. Put it on car battery terminals after they are connected to eliminate corrosion that can "grow" into the connection. But do not put it on the connector pins of your power connector. Use a good contact cleaner instead.

My opinion, YMMV, do your own research from reliable sources.

[ITSNO60]

Originally Posted by Al and Missy

I often see recommendations for the use of dielectric grease on connectors. As a retired electrical engineer, I always wondered. By definition a dielectric is an insulator. I finally decided to look into it and this is what I found.

"Ensure that the grease does not touch the path of electrical currents or where parts are connecting. This is because the grease is an insulator, and it disrupts the flow of currents. Therefore, it is recommended to use dielectric grease on surfaces of electrical parts where the currents are not passing."

Put it on the outside of CATV connectors before sliding the covers on. Put it on car battery terminals after they are connected to eliminate corrosion that can "grow" into the connection. But do not put it on the connector pins of your power connector. Use a good contact cleaner instead.

My opinion, YMMV, do your own research from reliable sources.

I did a lot of research on this myself a while back and came to the conclusion that I will keep using it as I have been. When you tighten down your connection the dielectric grease gets pushed out of the contact areas but forms an airtight seal around them, filling the irregularities. With or without the grease the metals will make contact where they can and the voids will remain where they are, but with the grease the voids will fill and stop oxidation. I read about conductive grease as well and I read an in depth study on it where they had failures with it that they didn't have with plain dielectric grease due to incompatibilities of the tiny metal particles in the conductive grease and the terminal material. Anyway that's my conclusion and haven't had problems after doing it that way all my life.

As far as my plug end it's not a big deal to change it on the spot, I think the biggest offender is going to be worn out pedestal receptacles which we don't have a lot of control over.
As far as cable connections, I don't use it on those, not sure how well it would work since the connection is just a wire in a hole.

[Al and Missy]

My concern is the sockets in these connectors are, in my experience, at best a double blade wiping connector. If they make a good connection it is only over a small area. The 30A connectors get more use than the 50s. That is why I carry an adapter and will use the 50A connection if the 30 doesn't look or feel right. The only thing that could be at risk is my cable since there is a 30A breaker in my trailer.

I agree with you fully in a tight clamped connection.

Your research and experience is broader than mine, as may be true with others. That is why I put the disclaimer in my post.

[CruizinDux]

Just to tag on with a similar experience on a trip last fall to CA. Stopped in Bakersfield...high 90's and everyone's AC was running. Nice newer park (with newer ele/pedestals). EMS-PT30X (newer) at the pedestal and ran AC most of the night. All good and no alarms. Next morning, could not disc the SP at TT. Had a deadline heading for wife's 50th class reunion in the bay area, so disc from the EMS and wrapped the cord around the Fiamma. Didn't think to look for errors there but power was on in the TT and everything worked, nothing tripped.


Got to Friends at Livermore and their side yard...had to remove the TT connection (which on a 20 is not a standard shelf product due to the angle of the romex) and cut it off. Bought a new Furrian cord locally and ordered from Amazon and new TT connection (that didn't fit with the romex approach as AS apparently in the thin wall section needed an approach from the bottom vs the back....and no dealer in the bay area, AS or otherwise had one). Crud. Netx stop go by a batter charger.


Thinking back the night before in Flagstaff (hot too!!) , had some difficulty attaching the SP to the TT, later thought maybe someone debris fro the very gravely & dirt surface pads. NOte to self, when home give all contacts and cleaning and some dielectric** (see note at end)

Anyway limped to the reunion and then back to MO on a battery charger setup. AS in StL had a stack of the connection on the shelf. Go Figure.

Some folks said, debris in the SP>TT connection. Others said low voltage at the park (my first reaction).


Back to Livermore, when I cut off the TT connection I could clearly see the neg lead was discolored and the screw are in meltdown. The ground was fine but the black hot I was able with some difficulty turn in the connection. Wouldn't necessarily say loose and nothing melted but was twist-able if that's a word.

Long route to the unknown part is that AS has a torque spec for these screws

https://www.airforums.com/forums/f37...-230779-2.html post 26

"this from JC..."The setting for a 30Amp inlet is 14-17 inch lbs. on a 50Amp it is 20-25 inch lbs. "

This item is now on my summerize check list! I now carry a batter charger as well.

Happy trails
b


p.s. and what got me started on this post, after this happened there was a long thread with much discussion re dialectic grease, when and where is should be AND SHOULDN'T be used. The latter was a surprise.



I think this is it as the dates are about right.


https://www.airforums.com/forums/f37...-230475-2.html


but also found this one in my search


https://www.airforums.com/forums/f37...se-205771.html

[WellSaid11]

OP - several people have asked: did you have a surge protector?

If so, please provide details such as internal/external, brand, model, errors if any, etc.

Thanks.

[John Ware]

Originally Posted by Al and Missy

That thing with the bifocals is going around.....

You should have seen me getting up and down off the floor. I am wondering also if the OP was using an EMS or a surge protector and would it have given him a warning.

[ROBERTSUNRUS]

Hi, poor connections cause heat and melt. This does not trip circuit breakers.

[Mach5]

That yellow plug looks suspiciously like a replacement. Is it possible your power cord was repaired at some point? Whenever I use a screw terminal replacement plug or receptacle, I wait a while after attaching the wires and go back to re-tighten all the screw connections before reassembly.

[tjdonahoe]

Loose connection there

[pteck]

Originally Posted by 10Smiles

I'm guessing it is a resistance issue at the power cord/extension connection (the site of the burned components). This can be due to several things, corroded pin or socket, not good contact between one of the pin/sockets, or?? This is why you stay away from extension cords when running high current/long duration appliances. Similarly, when you run a space heater (high current/long duration) it is HIGHLY recommended to not use an extension cord (even of large gauge - more than required for the current draw).

Ding ding ding. This needs to be highlighted more.

It's surely a combination of factors, perhaps even a marginal electrical system of the campsite, but ultimately resistance created by extensions, worn connectors, etc., led to overly high current draws.

Inductive loads such as A/Cs, draw constant power. That is if they need for example 2000W, they will draw that in voltage or current, because power = voltage * current. Current may be used to make-up shortfalls in voltage.

Problem comes with too high resistance created by extensions, connections, and perhaps too much load by everyone in the campsite - this causes voltage to sag. As said earlier, current will be used to compensate.

Electrical elements are usually limited by current, so in this case, you were clearly drawing over 30amps. Creating heat at the point of most resistance. Fortunately, that was at the junction of the extension, and not somewhere more difficult to repair.

TL;DR - absolutely avoid extensions if possible when drawing lots of power.
TL;DR #2 - If breakers are tripping, don't sidestep them before evaluating possible reasons. A voltmeter would be useful in this situation.

[RoverZac]

I don't want to read through all the posts if they're like the first page. Everybody has a different theory, but the actual cause is in the original post.

Camper drawing over 30 amps, pops 30 amp breaker. The breaker is doing its job to protect its wiring.

Switching to a higher output receptacle (50 amp) and attempting to draw over 30 amps through plugs and wiring designed for 30 amps max will overheat and distort your plug and can cause fire... as you noticed.

This is a big no-no. If the 30 amp breaker keeps popping, reduce your load. Never oversize your breaker to prevent it from popping. It's there to protect the wiring.

/solved

[GrandpaMac]

Originally Posted by Flathead1984

I am in a KOA in Montana. 30amp kept tripping. Moved the plug to a 50amp outlet with dog bone. That was 2 weeks ago.

While inside (95 degrees outside) my power went out.

Went out to check breaker on box, and the connection between my 30 amp cord and extension (I was 2’ short of box) was on FIRE!

I have been using these cords for 2 years.

What cause?

Ed

To me, we are missing a significant contributor- the post says he was using an extension. All of our ‘shore power’ cords are big ‘ole resistors. Resistors reduce the voltage, and in doing that, create heat. Plugs and receptacle ALSO drop voltage and create heat. We ALL know not to string cords together, but we do it. Then, the increased current overheats things.

He MAY have been able to sidestep this issue by moving the rig two feet, and not using an extension. Let’s see - we had a plug and receptacle at the pedestal for the dog bone, another plug/receptical set between the dog bone and the first cord, and another between the two cords, and yet another at the RV inlet. Add the resistance of the wiring in the dog bone and the two cords, and we have real issues cropping up. I would say he simply got a fire at the worst of all those connections!

[10Smiles]

Originally Posted by GrandpaMac

... I would say he simply got a fire at the worst of all those connections!

And probably at the safest place to have a fire.

[onemorejeff]

Here's some light reading regarding the limitations of older style plugs and how much better the smart plug replacements can be. It is a marine website but electricity is electricity. https://marinehowto.com/shore-power-...tplug-vs-1938/