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Sunday, January 2, 2000

Friends of Gary - Mike Sokol


From an RV Doc reader:
I own a 2006 travel trailer. My question is when I plug the power cord into an AC socket with an adapter (15/20-amp) or without the adapter (30 amp), I draw an arc to the terminal spade lugs and over time they have become pitted. Why does this happen? Should I turn off the main trailer breaker before connecting to the power source? Jim M., (Halifax, NS, Canada)


Mike's Response:
Ah yes, when sparks fly. Contrary to what you might think, the bright yellow & green sparks you see when unplugging an extension cord or the shore power plug are not electrons zipping around, but rather tiny bits of superheated copper burning in the air. Where does that burning metal come from? Well it comes from the metallic contacts of your extension cord or shore power plug when they're plugged or unplugged under a load. That means that every time you plug and unplug your RV shore power plugs while the pedestal is powered up, you're giving up little bits of metal from your contacts, which eventually shows up a pits in the surface. And this is a slippery slope, since these tiny pits tend to spall off more metal creating even larger pits, and so on. Eventually you'll lose enough metal from your plug contacts that they'll begin to heat up under normal current loads. Not a good thing since they can get hot enough to melt the plastic plugs or even catch on fire.

What to do? Well, ALWAYS turn OFF the circuit breaker on the campsite pedestal before you plug or unplug any shore power or extension cords (The RV Doc's been telling RVers that for years!). After you're securely connected, you can then turn on the pedestal breaker. The bad news is that if your plug contacts are already pitted from years of plugging or unplugging under power, there's really nothing you can do to restore the surface. Sure, you can use a little emery paper to brighten up the copper surface, but deep pitting means that you must replace the power cord. Make sure you get all the connections wired correctly though, as an improperly wired shore power or extension cord can create a dangerous hot-skin condition. So check with the manufacturer or get a certified RV technician to wire on a new shore cord. Nobody wants to be shocked (or worse) from their RV. 


Mike Sokol

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