RV Electricity – Life-saving space heater safety reminders


By Mike Sokol

Dear Readers,
Since much of the country is gripped by the coldest winter in a generation, this is a good time to remind you about electrical safety for using portable electric space heaters in your RV as well as your bricks-and-sticks house.

Now don’t get me wrong, portable space heaters by themselves are generally designed to be safe. And the ceramic versions are self-limiting in temperature and will reduce their own current draw if the airflow is blocked. But the problem isn’t the heaters themselves. It’s that the USA electric outlets weren’t designed to be heavy enough for the task of providing 1,500 watts continuously for hours on end.

Here’s why. A little Ohm’s law tells us that wattage divided by voltage equals amperage. So 1,500 watts / 120 volts = 12.5 amperes. Seems safe enough for a 20-amp outlet, doesn’t it? Well, the next piece of the puzzle is that circuit breakers and outlets are only rated for 80% of their stated amperage when run continuously. So that 20-ampere circuit is really only rated for 16 amperes of current continuously (0.80 x 20 = 16 amperes). So now you’re down to a 16-ampere outlet providing 12.5 amperes. But remember, that branch circuit could be using 14-gauge wire instead of 12-gauge wire, which means it should only be using a 15-amp circuit breaker. And 80% of 15 amperes is only 12 amperes. Yikes!

So a 1,500-watt portable electric space heater can put even a well-maintained electrical out right on the edge of failure. Now add in corrosion on the heater’s plug and the wall outlet, maybe throw in a too-small extension cord and possibly a power strip or two, sprinkle some flammable objects like newspapers around, and you have a sure recipe for an electrical fire.

How do I know this? Well, I reported on just such a fire last year near where I live. And I’ve heard of a few more recent house fires in my area that appear to be space-heater related. Read my past articles on space heater safety here (Part 1) and here (Part 2).

So what can you do about it? Well, first of all you need to carefully inspect the space heater’s plug for any signs of damage, overheating or corrosion. It’s not a bad idea to use a little fine emery cloth on the contacts to brighten them, and maybe some contact cleaner. Same for the wall outlet you’re plugging into. Make sure it’s not loose when you plug in and a spritz of contact cleaner is a good idea.

If there’s any sign of overheating or melting, have the outlet replaced immediately. And don’t use an extension cord on an electric space heater if at all possible. If you do need to use an extension cord it should be a contractor-grade cord built with 12-gauge wire and rated for 20-amperes. If you do have to run it unattended, see if it has a low power 600- or 750-watt setting. That’s way easier on the wiring and might be enough to keep the pipes (and possibly your toes) from freezing.

Finally, keep all flammable materials such as paper or fabrics away from the heater itself, but especially off of any extension cord plugs. That’s where the overheating and fires generally start. I don’t want to read about any more electrical fires caused by electric space heaters this season. It’s just too heartbreaking.

Let’s play safe out there….


Mike Sokol is an electrical and professional sound expert with 40+ 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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Mike Sherman

Very useful information, especially during the winter months.

Tony Madia

I posted this once but somehow it was erased. Let’s try again. Mike, if I need to replace an outlet is there a specific outlet made for RVs or a regular household outlet? Do you have a recommendation for an outlet to purchase?

Steve Lawhead

When I use my heater I usually put it on low unless I am physically present. If it’s on high I’ll check the cord and plug occasionally for excessive heat. I’ve replaced the outlets I use for heavy loads with regular outlets instead of the cheap self contained speed box outlets they use from the factory.

Dave Telenko

So WHOM do we have in the RV industry that will protect us from the RV industries in their building an RV to a real standard? Like electrical, plumbing, heating & construction. I see on all new RV’s a seal at the front door that says RVIA. If that’s supposed to mean something about their safety & construction of an RV, it must have been written by the RV industry, as the RV that I have wouldn’t pass any building & electrical & plumbing codes. One thing that has really got my attention is the outlets that they use. They count on “someone” to push a shielded wire into a thin 2-prong connector & hope it makes contact, I’ve had 1 fail. I like the more positive one that takes a skilled person to install them! There are just NO checks & balances in RV’s, which have because there are no inspections done on every RV, like the ones that HAVE to be done in residential & commercial industries!

Cee Taylor

I purchased a Vortex VH200 a few months ago because of the safety features and very quiet motor. I wanted something to give me a little warmth while working on the desktop in the back of the house. When I leave the room I shut the heater off, so feel comfortable about using it in the house. I bought a 2 yr old motorhome 8 months ago & have been doing lots of reading & Youtube to learn how to keep up on maintenance, etc. Sometimes I’m not sure if I can trust what I am reading – seeing.
I read that I should exercise the on-board genny for 2 hours every month with a load, such as a 1500w space heater. What do you think about running the space heater for that length of time? Am I inviting trouble?
Thanks, Cee in Montana


Mike, I think your article about using portable electric heating is timely and well done. That being said a simple solution to heating your RV with the parks shore power, is to get a CheapHeat Hybrid Electric system installed in your RV. I suggest anyone thinking about heating their RV with portable electric heaters consider the CheapHeat hybrid system. With the CheapHeat system you don’t have these safety issues you’ve been talking about. Because the CheapHeat system has been engineered from the ground up to be sure you don’t have any overloads plus, its UL listed and RVIA compliant. Check it out at http://www.rvcomfortsystems.com or call them at 425-408-3140.

Tony Madia

If I need to replace an outlet, is there a special outlet to purchase specifically for a RV? Please recommend what to purchase.

John Whitney

Good article Mike


Mike: I really enjoy reading your articles. Unfortunately, some of the stuff is FAR too Technical for most people and many people who read this, COULD care less.

Space Heaters (IMHO) are inherently DANGEROUS. In a RV even more so!

I have never owned one and will never have one in my House or RV.

One of the single biggest statistical facts in many Fires where I live, during cold weather, Space Heaters have been the culprit. Wrong configurations, people NOT reading the instructions, plugging units into an underrated outlet where the Unit overheats. And On and On!

The really sad thing is People DON’T think about SAFETY! So, no matter how much is written about Space Heaters, I don’t like them and will never own one!

Joseph Weinstein

Mike, another thank you for the constant educational instruction you provide. I recently purchased a space heater, did pay attention to the watts, etc., but this information is really helpful in regard to keeping us all safe.

Chuck Howe

Would an oil filled heater be better as I believe it “cycles” on and off as it gets to temperature OR does it really continue to draw power?