RVelectricity – Avoid potentially dangerous shore power meltdown

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By Mike Sokol

Dear Mike,
I’ve noticed that my shore power plug is looking pretty bad. Instead of being pretty brass colored like the new ones in the store, it’s sort of brown with a bunch of little pits. Is there a way to clean this? Is it dangerous? Why does this happen?  —Caleb

Dear Caleb,
All great questions, and let’s start with the last question first. The brown color is oxidation from moisture and air (oxygen), but the little pits are caused by arcing of the contacts when plugging and unplugging it in the pedestal outlet with the circuit breaker on. Always turn off the circuit breaker in the pedestal before plugging or unplugging into shore power to avoid these fireworks.

Those sparks you see aren’t electrons zipping around they’re actually tiny bits of super-heated metal launching off in all directions. Here’s a previously unpublished picture from one of my short-circuit overload experiments:

This photo looks like it’s been created in Photoshop, but it’s a real frame grab from a video linked to HRDL (my High Rate Data Logger). You can actually see the individual bits of burning copper launching off into space, with one of them bouncing off the clamp meter.

This show us two things… First, you should always wear safety glasses when working around any live electricity. Those sparks could easily injure your eyesight if you take a hit in your eyes. And secondly, always turn off the pedestal circuit breaker before plugging or unplugging into shore power.

Next let’s address the brown oxidation on the contacts. The best contact cleaner I know is DeoxIT D5, which not only removes the oxide, it also leaves behind a layer of lubrication that makes it easier to plug and unplug the connection. Yes, this is pretty expensive stuff, but even if you use a little squirt each time you plug into shore power, that can will last for seasons of camping. I think it’s cheap insurance.

For really severe oxidation and pitting you can also use very fine sandpaper or emery cloth to help smooth the surface, but once the contacts are damaged that much it’s really best to replace the entire plug with a new one.

And yes, this can be dangerous. Oxidized and pitted shore power plugs and pedestal outlets can easily overheat, causing meltdowns and potentially a fire.

You’ll want to check your plug for any signs of overheating, especially during the day when your air conditioner has been running for hours. If it feels hot to the touch, that’s the sign of a poor connection that’s only going to get worse. So clean your shore power connectors now, and avoid meltdown and shutdown later.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.

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Aubrey
10 days ago

Can you spray the receptacle also?

Tim
10 days ago

We all know (and Mike reminds of this) to turn Off the circuit breaker before removing your shore power cord from the pedestal, but one of the things I was taught as an apprentice electrician is that you should always Look Away When Turning On A Circuit Breaker.
You never know when a circuit breaker (which has been cycled thousands of times)
could have a catastrophic failure.
Better safe than sorry.

Thomas
11 days ago

I bought and use a 50/30 amp adapter whenever possible. Ive never seen a 50 amp plug burnt up whereas the 30 amp one are usually burnt. Overloading your cord? Yes 50 amps is more than 30 amps but your RV has a circuit breaker that limits your use. I’ve not had trouble since I’ve started doing this.

Bob
11 days ago

I belong to a few motorcycle discussion websites and I have been pushing Deoxit for a number of years. Motorcycles are notorious for oxidized connectors and switches. Part of my yearly maintenance is to spray the switches and any connectors that may be subject to outside elements. It also works great for the sockets on the light bulbs. It is safe to be used on plastics.
A lot of people swear by WD40 and regular contact cleaner. WD40 attracts dust and contact cleaner removes any lubrication on the switches. Not so with Deoxit.
This stuff really works.