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
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.
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.