RV’s power outlets are melting. Help!

Dear Mike,
I noticed the outlet for our microwave in the motorhome had started to melt. Upon removal of the outlet I saw that the wires connections were not screws but pressed into a pronged connection. I replaced the outlet with a standard screw-type outlet. I checked other outlets and discovered the one to the washing machine also was burned and melted due to these press-on connections being loose and heating up. I don’t know if the RV industry still uses these but would advise people to check all their outlets, especially high-amperage appliances. —Ray

Dear Ray,
That’s a great point, and something that should really be checked by every RV owner. There are basically two different ways to secure the wires on the back of an electrical outlet. The traditional Side-Wire method uses screws on the side of the outlets, and you make a half-loop of the bare wire which is then captured under the screw. This was the gold standard receptacle and what I use in most of my power connections.

A second, newer method still uses machine screws, but instead of wrapping a loop of the wire around the screw itself, a length of stripped/straight wire is put into a hole, and a side-mounted screw clamps down on it. This Screw & Clamp Back Wire outlet is possibly more robust than the original Side-Wire loop method described above since any tugging on the wires can cause the screws to loosen.

What you’ve described, and I worry about a lot, is a new assembly method called a QuickWire or BackWire outlet. This is really quick to install since you just have to strip off the appropriate amount of insulation and “stab” the straight wire in the hole. There are little spring fingers which dig in and hold the wires more or less in place. But without an actual machine screw to provide compression of this connection, any sustained amperage from a high-wattage appliance can cause this spring-grip system to overheat, which leads to a higher resistance contact with even more heating, and the possibility of a melted plug or even a fire inside of the wall.

It’s pretty simple to tell what kind of outlet you have in your RV. After shutting off all power, you can remove the outlet cover with the center screw, then remove the two screws on the top and bottom of the bracket. You should then be able to pull out the outlet a few inches to see how the wire is fastened. If it’s simply stabbed in the back of the outlet without any side screws holding it in place, then you should replace the outlet with a best-quality outlet that has side-screws for the connection. And while you’re at it, it’s a good idea to replace ALL of the QuickWire outlets with screw-type outlets. You never know when you’re going to plug in a hair dryer or portable space heater, and both of those are really heavy loads.

And this is not the place to go cheap. Buy only the best-grade commercial outlets that keep your electrical connections cool and deliver all the voltage to the load. And if you’ve overheated a power cord that was plugged into an overheated outlet, you’ll want to clean the oxidized contacts with super-fine sandpaper, or replace the entire cord and plug if there’s any sign of melting. I like the Leviton 5252 series which are available HERE and in many big box stores.

Oh, if any of you want to geek-out, you can download the spec sheet on the Leviton 5252 outlet (actually called a Duplex Receptacle by the electrical industry) HERE.

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UPDATE

I don’t know how I missed this, but several of you said I had the wrong type of outlet that was melting. So I did some research and you are indeed correct. There is a class of wall outlets that use non-stripped wire to make connection via a set of sharp blades. This seems like the worst possible idea for any outlet that needs to carry significant continuous amperage for a microwave or space heater.

I’m going to get a few of these and run some load tests to see how they perform. Of course these are quicker to install in shallow walls, but safety should be our main concern.

Let’s play safe out there….

 

Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit NoShockZone.org for more electrical safety tips. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

##RVT845

 

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22 Thoughts to “RV’s power outlets are melting. Help!”

  1. Tim

    The advantage of the RV/mobile home approved receptacle is that they do not require a box. That makes them fast and cheap.

    Replacing with a residential or commercial receptacle is a great upgrade but requires the installation of a box to be safe and to meet building code.

    1. Mike Sokol

      Yes, you do need a box to install any residential style outlet to make it code compliant and safe.

  2. Gary

    Mike, I couldn’t agree with you more.
    I worked in a electronic research & development lab for 40 years which included failure analysis on high reliability products. This experience has given me a knowledge and a feel for what is required for a reliable/safe product. Several months ago I upgraded from a camper to a TT and decided to replace a receptical with one that had a USB charger. I was concerned the moment I removed the back and saw the connections style (sharp blade type). I feel these recepticals are not safe and prone to failure. I have since replaced all of them in my trailer. Also, be aware that they use these to also connect to branch circuits. I had one receptical with 3 sets of wires ( 1 set fell off when I removed the back) that fed 4 other plugs. This included one that powered my electric heater and another that powered a hair dryer. For safety concerns I will not be using them in my trailer.

    1. Mike Sokol

      Gary, yes I also worked in a testing lab where we built, calibrated and qualified military electronic components. We had vibration tables we used for failure analysis and my concern with RVs is that they use many products designed for the home environment rather than mobile applications. Products designed for your car or truck undergo rigorous vibration and temperature testing, while products for the home get a much more relaxed test cycle. Marine products are generally tested much more rigorously and also undergo salt-spray testing, etc… But that’s also why products sold to the marine industry are a lot more expensive.

      1. Gary

        Mike, sounds like we had the same job and equipment. Mine was military aerospace.
        You are correct about the equipment used in TT/RV. I personally wouldn’t use them in my home much less my TT. Even though my TT is brand new, I am replacing items and making modifications to ruggedize my trailer to reduce problems in the future.
        If I was forced to use the sharp blade style receptical due to size restrictions I would make the following changes. Allow only 1 set of wires per receptical (no feed thru circuits). Secure the wire with a cable tie within inches of the receptical (they currently do not have strain relief). Where the wire enters the housing, fill the void between the housing and wire with GE silicon rubber to further support the wire from vibration. If at all possible I would replace them with “old work boxes and a quality receptical. Hopefully in the future stricter quality standards will be required.

        1. Mike Sokol

          Gary,
          Yes, we likely did the same sort of thing. And that’s why we understand the evils of vibration. You’re ideas are spot on, but it would be a better fix to have a real metal box with quality receptacles.

      2. Gary

        Looks like our jobs were the same with mine being in military aerospace. I agree that tougher standards are needed. Items used in trailers I wouldn’t use in my house. If I was forced to use the plugs you mentioned I would do the following. Have only one set of wires in an assembly. Secure the wire within inches if the device uses a cable tie to reduce vibration. For strain relief fill the void where the wire enters the housing with GE silicone rubber.

        1. Gary

          Sorry for the duplication. I received an error message that it wasn’t accepted.

  3. Ray

    I am the original poster and Don B. Is correct that is the outlet I was referring to. This was on a 2000 Monaco Knight. I am sorry I did not save the outlets for show and tell. I also did not write Help at the heading.

    1. Mike Sokol

      Ray, thanks for your original post. And while you didn’t actually say “Help”, that’s up to my editor(s) to attract readers. But it is a shame you didn’t save the offending outlets. I’m gathering gear that has failed in the field so I can show manufacturers what does and doesn’t work. And no matter what kind of test I can set up to simulate road usage, real road time includes variables I can’t account for on the test bench. So if any of you have a component that failed in a spectacular way, then I want to know about it and possibly have it shipped to me for a forensic analysis. And that will help all of us get better products.

  4. Ray

    I am the original poster and Don B. Is correct that is the outlet I was referring to. I am sorry I did not save the outlets for show and tell. I also did not write Help at the heading.

  5. David Kaiser

    Have installed a Progressive Industries EMS-LCHW30 in our truck camper over the winter, before the installation we used a Honda EU-1000i to charge our boat batteries each night and then power the camper for tv, laptops, etc. and leaving the fridge on propane. Now the EMS won’t let power through because of an open ground (E-2). Didn’t I read something on this through your articles or the RV Newsletter? Thank you for all your great articles.

    1. David Kaiser

      OOPS, meant to say Honda EU-1000i

      1. David Kaiser

        Thanks, you are truly the best!

  6. Ed

    Mike, you missed the type of outlet he is talking about used in RV’s and Mobile Homes. They do not have a cover plate or electrical box to be installed into. You can recognize them by the two screws on the face used to hold them into the wall. They have a snap-on back used to cover the romex and hold the wires into the slots. Think of an extra large Scotch lock wire connector used to connect the wire, the connection pierces the insulation as the wire is pushed into the slot.

      1. Ed

        Bingo, I replace them if I have the wall space with a box and an industrial receptacle. The light switches are just as bad.

  7. Larry M

    Mike you have to remember when you’re dealing with RV OEM’s, your dealing with production minded people. Anything to save a few seconds or a few pennies is what they are all about. A side from the fact that the people that install the electrical in RV.’s are NOT electricians like you find in the residential construction trades. They are just people off of the street that are told to run this color wire from here to there with no real understanding of how electricity works.
    What even worse is that the people guiding these folks have a very limited understanding of electrical and don’t even realize that a 50 amp RV service is actually a 240 VAC service with tow 120 VAC legs that actually add up to 100 amps @ 120 VAC.

  8. Don B.

    Mike,

    Sorry, what you described above is not what the original poster was talking about. What he described is an outlet where no insulation is striped off of the wire and is simply pushed down in between two prongs designed to cut into the wire to make contact much like a scotch lock connector on low voltage wiring. All of what you describe above is far superior to the inferior garbage that the RV industry is using. I am amazed that these type of plugs are approved anywhere let alone in a mobile earthquake rolling down the road.

    1. Albert

      I agree with Don, I had the plug he is describing melt and had to replace it. The only thing plugged into it was a toaster oven. The wire connection, if you can call it that, melted. If you don’t push the wire firmly down to make a good connection, or vibration loosens the wire, it will spark and melt. I had no choice but to replace it with a like connector, due to the space of the thin walls.

    2. Mike Sokol

      Please send me a manufacturer name and part number of the type of outlet you’re talking about. Or take a picture of one and email it to mike@noshockzone.org. I’ve seen what you describe in really cheap in-line ON-OFF switches on a lamp cord, but they were only rated for 18-gauge stranded wire, not NM solid Romex. And, this is really common in 12-volt DC wiring “taps” for turn signals and under dash radio hookups. If what you say is true about wall outlets, then it’s even worse than I thought it was.

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