By Mike Sokol
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
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 Here’s a previously unpublished picture from one of my short-circuit overload experiments: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.
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.
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