30A to 50A Adapter Causes MH Fire

[Cubey]

Plenty of people would say my entire motorhome is unsafe since it doesn't have airbags and anti-lock brakes.

And heck, I'm at a MUCH greater risk of death or injury on my scooter than I am plugging into a 50A outlet with a good condition adapter stored outdoors. I have no desire to become a crispy critter so I practice safety with electricity.

Oh... and the original way cord was, it was a hard wired 25ft cord that was MEANT to be coiled and stored in the compartment for generator use. I didn't like having to wrangle the cord to get it out the small hole meant for running it out, or having such a long cord inside plugged up, so I did this:

Plan V - A van dwelling blog: 30A hookup modification

I made the excess cord into a 25ft extension cord with new 30A ends, meant for mending RV cables. (And yes, I will get around to fixing the hard wired harness insulation soon)

I do NOT use adapters in the compartment however even when on 20A service.

Accidents happen no matter how well you think you are prepared though. All you can do is be as safe as possible with what you have to work with. And don't do stupid, lazy things trying to cut corners.

[jerichorick]

I think Adaycj was referring to some of my statements. I can assure you, Adaycj, that if you lose the neutral on your 50A RV service it WILL cost you bucks for a new inverter and other things. I know folks that have had this problem. The 'protective' ground plays into the circuit at that point. I am not trying to be rude or argumentative. I am simply speaking from experience at one of the volunteer projects. The guy who was working on the rig in question did not verify the neutral. The folks using the rig had major and expensive problems.

I saw a mention of 'sticky breakers'. I think Adaycj will agree here that this is a more common problem than realized. One of the recommendations and practices I have used is to manually exercise the breakers once a year. This is a good practice even in your fixed domicile.

I have not noticed mention of the power control center of RV's. I am unfamiliar with most brands so I can only talk from my experience. I have had 3 DPs and each has had a power control center. When plugged into a 50A service the panel indicator told me I was on 50A. On 30 or 20A service I had to select which I was using and the amperage I was drawing was indicated. I mention this because of the way some of the discussion have gone. I am guessing this is not so in all RVs?

The folks with the fire have certainly gotten the attention of a bunch of us! This is a great and lively conversation. Too bad it had to start at the expense of these folks. I hope we all come away wiser.

Rick

[Route 66]

I too had always heard that leaving excess power cord coiled up could cause an overheat condition.

However, I always kept excess (50 amp) cord coiled up in the power bay. I would check it from time to time over the years and never found it to be hot. YMMV.

Regarding dogbones and connectors overheating, dirty or bad connections are a well known cause of overheating, but IMHO, internal defects are also a problem. Improper internal connections during manufacture or assembly and excessive flexing from repeated use can damage internal connections.

A lot of the adapters and dogbones appear to be cheaply made and I question their safety.

[94-Newmar]

Just as an observation I think we can all agree that any 30amp plug has much smaller/thinner/shorter blades as compared to the 50amp. If you accidentally drop your 30amp male end on the ground the blades will bend over very easily. As mentioned in various replies in this thread, owners keeping the blades clean and greased to prevent corrosion is another huge factor in having 30/50amp connections get so hot. I intend to switch over my 30amp connections and extension to nice twist locks as those blades are very thick and very heavy duty. Even though I keep mine clean and lubricated they still have a tendency to run pretty warm when in moderate use. Honestly I'm surprised the entire industry hasn't gone to twist locks.

[HD4Mark]

We had a 30 to 50 amp adapter burn up a couple of years ago. At a state park that only had 30A at the ped I ran my 50A cord to it and plugged in a standard "dog bone". The on board EMS recognized it as 30A and all was well until the power went out. We found the adapter melted at the ped, ruining it as well as the CGs plug. The breaker did not trip. A ranger replaced the plug and breaker just in case and we were lucky enough to have a spare adapter the MH dealer threw in.

Since the EMS will shut down things if we attempt to draw more the the amperage that is connected I really don't know what happened. Never had an issue again but it did make us think about the condition of the cords and what is running in the coach.

About coiling up the cords. The heating up idea makes sense but any of you that have an automatic cord reel like us have the cord coiled up. Ours winds it up into a round tub inside the electric bay. In a situation where the power ped is close to the bay most of the cord is coiled up in there. So should I be running more cord out on the ground?

[JohnBoyToo]

Cubey, you are probably right about others saying it's unsafe, I'm surprised they haven't forced you to sell

94, good observation about care when handling your cords !!

HD, I would, but that's just IMHO (and our new 5th is going to have a cord storage wheel, so I'll be testing soon I hope )

Now, would I roll it out when the ambient temp is 20 degrees ? probably not, but an unplugged cord in our southwest sun can almost overheat (just like we do !!!)

I have actually hurt my forearm reaching over the f350's bed sidewall to reach something and the black paint would be so hot it would cause almost a sunburn !

[gemini5362]

Originally Posted by Cubey

[moderator edit]

I have a pretty good grasp of electrical safety and wiring so I am not fearful of it the way you seem to be. I do all my own brake work too... but I know what's safe and what isn't.

We drive with huge tanks filled with gasoline or diesel. In a wreck it could ignite and you could burn to death. But you still put fuel in your vehicles, right?

Your propane tanks could rupture in a wreck and you could be blown to bits if the gas ignites, but you still fill them right?

Your batteries could explode in your face but you still have them, right?

It's all possible but the chances are slim so we take the chance. And statistically it's a chance worth taking since that's what you have to do to acheive a goal of driving somewhere, having propane for your stove, starting your engine and storing electricity for power when not hooked up to the grid.

Of all the dangers of RVs, a 30A cable plugged on a 50A pedestal is one of the least likely dangers assuming your cords, adapter and wiring isn't damaged and you don't do stupid things like trying to run 50A on it.

[moderator edit] I do not really care what you do with your motorhome other than the concern I might park next to you. I do not know how good a grasp you have of electrical safety. I spent 6 years in the navy working on an extreme high powered missile system. In addition to the ships power we had 3 50,000 watt generators to power the high power transmitter tubes on each of the beams. They spent a lot of time teaching electrical safety in the schools I went to. I went to college for electrical engineering they spent a lot of time teaching electrical safety. When I worked at Nasa on the S band telemetry system they spent a lot of time on electrical safety. When I worked at the steel mill in fort smith which had their own substation and were powered by a 1600 volt line which was brought down to all the voltages in the plant and converted to 250 volts DC at 4000 amps to run the two 125 ton cranes and the 6 15 ton cranes they had in the plant not to mention the furnaces which used electrodes which were carbon rods about 2 feet across to melt the stell. They were very big on electrical safety. I probably do not know anything about it at all I am sure you know much more than i do.

I do not know how you do your wireing or what kind of maintenance you do on it. However there are people that are reading this who might not check connections where the wiring comes in. They might be trying to use more current than they should. They read your post and think it is fine to just plug into the 50 amp circuit with their 30 amp cable. It is not a good idea. As far as the other stuff you mentioned their are dangers in anything. I use things as they are designed to be used. I would not hang a couple of 5 gallon jugs of gas on the back of my car and run off of them if I had a hole in my gas tank because that would be dangerous in case someone rear ended me. For the most part in my limited experience this is a mute point any way. Most of the parks I have been to have both 50 and 30 amp plugs in them or they just have 30 amp service. It has always amazed me why I can go to a park and see camper after camper sitting in a site that has 50 amp capability when the camper only is set up for 30 amps. The 50 amp sites cost more and there are usually a limited number of them versus 50 amp which limits the people with bigger coaches which need the 50 amp sites from being able to fully utilize their coach.

[Sky_Boss]

Originally Posted by wa8yxm

One of the very first things they taught me was to NEVER EVER coil an "In use" power cord. always pull it out you can snake it (Back and forth) but NEVER coil it.

I tested the theory.. I pulled about five amps through a coiled up 12ga cord.. That is a fraction of the rating (20 amps) of such a cord) and that coil got uncomfortably (not dangerously thankfully) hot

....

Thus I always pull the cords out and if needed snake 'em. Never coil them less they are unplugged.

OK My Friend...

You got my attention.

I guess the question is has anyone else heard of this and are there others that follow the same practice?

I'm not doubting you but I am a tad surprised that the manufacturers, especially those that have hose reels, don't seem to talk about this at all. Is there some kind of safety label I have missed?

[gemini5362]

Originally Posted by jerichorick

I think Adaycj was referring to some of my statements. I can assure you, Adaycj, that if you lose the neutral on your 50A RV service it WILL cost you bucks for a new inverter and other things. I know folks that have had this problem. The 'protective' ground plays into the circuit at that point. I am not trying to be rude or argumentative. I am simply speaking from experience at one of the volunteer projects. The guy who was working on the rig in question did not verify the neutral. The folks using the rig had major and expensive problems.

I saw a mention of 'sticky breakers'. I think Adaycj will agree here that this is a more common problem than realized. One of the recommendations and practices I have used is to manually exercise the breakers once a year. This is a good practice even in your fixed domicile.

I have not noticed mention of the power control center of RV's. I am unfamiliar with most brands so I can only talk from my experience. I have had 3 DPs and each has had a power control center. When plugged into a 50A service the panel indicator told me I was on 50A. On 30 or 20A service I had to select which I was using and the amperage I was drawing was indicated. I mention this because of the way some of the discussion have gone. I am guessing this is not so in all RVs?

The folks with the fire have certainly gotten the attention of a bunch of us! This is a great and lively conversation. Too bad it had to start at the expense of these folks. I hope we all come away wiser.

Rick

Rick basically I do not think there are very many cheap diesel pushers and at the price you pay it seems like they have a power control center. There are older ones that do not have them and I think a lot of the gas class A MH do not have them. I believe most of the 5th wheels and travel trailers do not.
You can buy them to plug into the pedestal and plug your power cord into them but they are hundreds of dollars and a lot of people do not want to spend the money for them. I have one on my tiffin and it works great. I plugged into a small camp ground and could not get power to my unit. The owner was helping me hook up and when i told him that I could not get power he said he did not know why he had just installed power for that site earlier that day and was sure he had wired it right. I asked if he had checked it with a meter and he told me he hadnt. I went to one of his older sites and it worked fine.

[Lincolnboy2]

Originally Posted by Pusherman

Mike, I agree.

I have had 2 coaches with 30A services, and both of them needed new plugs on the end of the shore cord, as the molded plugs would melt around one of the prongs due to resistance, causing more heat build-up, which would just make things worse.

Thus the advice. Get a new 30-50A adapter every couple years, keeping the 30A side of the plug in good shape. Keep your shore cords short as possible - also building up less resistance and heat.

I agree 100% I carry two spares at all times now after my first year of all that mess!

[Lincolnboy2]

I too am concerned about this 'coiling' issue.


While traveling, my cable is coiled and plugged into the generator outlet. When at a CG, I withdraw only the amount necessary from the coiled cord to reach the pedestal.

[steveclv]

The issue with the coiled 'in use' power cable is that the inductance generated creates heat and that is what causes the cable to heat up - you can try it with a regular garden extension cord running close to it's maximum amps - you will be surprised how hot it will get if left on the cord winder.

Figure of 8 cancels out the inductance.

It has nothing to do with broken strands or any physical damage issue.

[Lincolnboy2]

So one should just lay the cord in a lot bigger loops in the bay then...

[steveclv]

Originally Posted by Adaycj

Wow. As a licenced electrician I am very worried about some of the concepts in this thread.

The only thing "out of the ordinary" with RVs is that sometimes we use wire rated for 30A connected to a 50A breaker (with adapter). It is normally not a concern because there is a 30A breaker in the circuit too. If the circuit has a low resistance failure of more than 30A but less than 50a before the 30A breaker there will be trouble. It is a known risk and does not appear to be the trouble in this fire.

Plugging a 50A or 30A RV into a lower rated circuit on a pedestal, home, or business is not a problem. The power from the pedestal, home, or business already has circuit protection small enough to match the rating. If they do not it is a failure of the pedestal, home, or business not the RV or adapters.

I have to take issue with this statement from a licensed contractor because I believe that you may be wrong.

The length of 30amp cable and any connectors between the Pedestal and the first 30amp circuit breaker in the RV are NOT protected by a suitable circuit breaker and that is in breach of code. A failure of the 30amp circuit breaker or a failure of the cable and connector between it and the pedestal are 'protected' by the 50amp breaker in the pedestal and that is not acceptable.

Please correct me if I am wrong but surely you must protect wiring and connections with a suitably sized breaker which is not happening in this case?