RVelectricity – Just Ask Mike (J.A.M.): Avoid dangerous 15-amp outlet overload

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. This week I discuss 15-amp outlet overload and how to avoid this potentially dangerous situation.

Dear Readers,
I was recently asked to help figure out why an outlet overheated that was feeding a 30-amp RV. I was confused at first until I asked for and received some pictures of the subpanel and outlet involved. And once you see it all, the answer is pretty clear.

Service panel

The incoming service panel had a 60-amp 2-pole circuit breaker feeding a subpanel maybe 100 feet away with 6-gauge wire. And that’s exactly what you need for this type of installation, which appears to be code compliant. So that’s not the cause of the outlet overheating.

Subpanel

But the subpanel feeding the 50-, 30- and 20-amp RV outlets looks a little suspicious. While it does have a 2-pole, 50-amp breaker for the 50-amp RV receptacle, and a 1-pole, 30-amp breaker for the 30-amp RV receptacle, there’s no 20-amp circuit breaker in sight. Plus, I don’t see any GFCI protection, which is required for any 15- or 20-amp receptacle mounted outside. So, I wonder what’s going on? Now it can be told!

Every picture tells a story (Thanks, Rod Stewart)

In the final picture you can see a pair of 15-amp duplex outlets that were connected to the 30-amp circuit breaker. To the casual observer (and maybe a DIY installer), this would seem to make sense. That’s because 15 amps plus 15 amps adds up to 30 amps, and somehow the outlets will sort out how much current they need. WRONG!

In this case, one of the 15-amp receptacles was forced to carry up to 30 amps of current to the RV with its air conditioner running. And as you know if you’ve watched any of my NoShockZone videos, asking a conductor and connector to carry twice its rated current is a recipe for overheating and possibly a fire.

Where’s the GFCI?

And no, there’s no GFCI protecting these duplex outlets, which is a big code violation. All outside 15- and 20-amp outlets require GFCI protection, which can be either in the circuit breaker or the receptacle itself. But be there it must. (Thanks, Yoda.)

But don’t be confused by the first version of the 2020 Code which required GFCI protection on the 30- and 50-amp receptacles. They quickly reversed that decision, and GFCI breakers are still only required on your 20-amp receptacles, not the 30- or 50-amp receptacles. So don’t let your electrician talk you into GFCI breakers for 30- or 50-amp shore power receptacles.

Should I install 15- or 20-amp outlets/receptacles?

While a standard duplex receptacle with parallel blade orientation is called a 15-amp outlet, in reality it can be connected to a 20-amp circuit breaker with 12-gauge wire and will carry 20-amps of current safely. However, the 20-amp duplex receptacles with the T-slots are generally heavier built, so I always install the 20-amp version just for the more robust internal connections.

And never use stab-style outlets which tend to overheat under continuous load. You’ll want to pay a few bucks more and get screw/clamp style outlets for a more secure connection on the back.

So are they called outlets or receptacles?

Well, they’re both, actually. If you talk to an electrician or an engineer who is steeped in NEC code language, the are called Receptacles and Cord Caps. But if you’re a consumer/layman, they are generally called outlets and plugs. So who’s correct? Depends on who you’re talking to.

When I’m teaching electrical troubleshooting classes to electricians and RV technicians, I call them receptacles and cord caps. But when I’m teaching electrical safety classes to consumers, I call them outlets and plugs. And sometimes (like above) I call them both at the same time.

Finally, please hire an electrician!!!

If this is the first time you’re reading anything like this, then you are definitely NOT qualified to install a pedestal outlet for your RV. There’s a lot that’s not covered here, and doing this incorrectly can result in a dangerous installation that could create a fire or shock hazard, and even destroy your RV’s electrical system. And without properly shutting off power in an electrical box (and keeping it off), you could kill yourself from electrocution.

So PLEASE find a licensed electrician to help you get the proper permits and do the final hookups. Most of them will allow (and even welcome) you to dig your own trench. But do not be poking around in a live electrical panel unless you’re properly trained in all safety requirements including LOTO (Lock Out/Tag Out) and required PPE (Personal Protective Equipment).

That’s a wrap!

While some of this may sound like hieroglyphics to many of you, it’s all true. And I’m always amazed at what a DIY person will attempt on their own without any training or tools. So please don’t go outside of your skill level when working with electricity. This is one thing you definitely don’t want to learn on the job.

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

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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