RV Electricity – Life-saving space heater safety reminders

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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
Mike Sherman

Very useful information, especially during the winter months.

Tony Madia
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?

Mike Sokol

If you have room to fit in a shallow box, then here’s what I wrote last year about the various types of outlet designs: https://www.rvtravel.com/quickwire-outlet-warning/

Steve Lawhead
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.

Mike Sokol

That’s the safest way to handle electric space heaters.

Dave Telenko
Dave Telenko

Mike 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.… Read more »

Mike Sokol

Dave, the RVIA adopts the electrical code in the NFPA 1192 and 1194 books, which references the basic electric code in NFPA 70. While I’ll agree that I don’t like those quick-connect outlets, fact is they’re allowed by the NEC. I have been in discussion with a few guys on the latest NEC code committee, but I’m just one guy just doing my best to educate the manufacturers, RV technicians and consumers about RV electrical systems.

Cee Taylor
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 more »

MikeJ
MikeJ

I run mine once a month for 30 minutes with one A/C on. And don’t forget to use a fuel stabilizer if parked for any length of time.

Cee Taylor
Cee Taylor

I have an ADCO cover on my MH so decided not to use the A/C to put a load on the generator because the cover may not allow for enough ventilation. What do you think?

I did add fuel stabilizer when I parked it in Oct.

Can you tell me why you should put a load on the generator? I have read that over and over but have never come across why.

Thanks, Cee

Mike Sokol

Cee, The reason why you need to provide a load on a generator is that it needs to be fully warmed up to boil any gasoline and other contaminants out of the lubrication oil. If you were to start and run it without any load once a month, in a year or so it would likely rot out the exhaust system from the acids that are created from condensation and unburned gasoline in the crankcase. A reasonable load on the generator assures that the crankcase and oil will get hot enough to eliminate this problem. Another reason to exercise your… Read more »

Mike Sokol

A 1,500 watt space heater on a heavy extension cord (not a power strip) with clean and undamaged connectors should be perfectly safe for this usage.

LARRY MCGAUGH

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… Read more »

Tony Madia
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.

Mike Sokol

Tony,
Most (perhaps all) modern RV manufacturers use something like this shallow design which uses a stab-thru connection: https://tinyurl.com/y9k68rbg
While I don’t think this is the best kind of connector to use for high-amperage loads such as electric space heaters, it should be safe for most loads. However, I do know a lot of DIY RV owners who replace this type of RV outlet with a more robust commercial-duty outlet, but that may not be possible with a lot of RV designs.

John Whitney
John Whitney

Good article Mike

Jeff
Jeff

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… Read more »

Mike Sokol

Jeff, Yes, I do realize that many (or perhaps most) people don’t care about understanding electricity or safety, which is why I’m constantly beating the drum about never accepting feeling an electric shock as normal. Back in the ’50s and ’60s it was all too common simply due to a lack of modern grounding procedures. But nowadays, if you ever feel a shock (even a little one) something is terribly wrong that could kill you or someone else the next time. However, technicians who work on your RV (and take your money) really SHOULD know all about electricity and how… Read more »

Jeff
Jeff

Thanks Mike: Here’s a question for you. We have some friends visiting from Colorado. 5th Wheel Trailer. I have them plugged in to my 50 amp service. My RV is sitting on the Batteries for Now. Anyway, I plugged in my extension cord via my SURGE Protector to my Friends 50 to 30 Amp Dog Bone. No Power to his RV. Figured maybe the Surge Protector was blocking something. So removed the Surge Protector and Plugged the 50 Amp Extension in straight and low and behold power was supplied to his RV. Your thoughts would be appreciated. Thanks, Jeff

Mike Sokol

What’s the brand and model# of the surge protector? That’s the first thing to consider.

Jeff
Jeff

Progressive 50 Amp External Plug In!

Mike Sokol

It sounds like your 50-amp service has a problem such as an open ground. Is it giving you any kind of error message? Do you have any other way to test your outlet. And remember that dog-bone adapters can fail internally.

Jeff
Jeff

I thought the same thing. But, the BIG RV has been plugged into it for months with no problems. And the CODE SHOWs E 0, meaning no problems. It has been working fine on my BIG RV and I have Tested it, using the NON Contact Tester. So, my guess is as good as yours.

Joseph Weinstein
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.

Mike Sokol

Joe,

Thanks very much. Let’s keep safe out there….

Chuck Howe
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?

Mike Sokol

Any heater that’s set to a temperature that it can achieve will cycle on and off. For example, if you set it for 70 degrees and it has enough wattage to get up to 70 degrees, any heater will cycle on and off. However, if there’s insufficient insulation in the room that the heater can’t bring up to the temp to 70 degrees (or whatever you set the thermostat at), then it will run continuously. Also, many (most?) of these heaters have a full-on setting that won’t shut off at a set temperature, so they’ll run continuously no matter what… Read more »

Randy Coleman
Randy Coleman

What is the best RV heater to have, Mike?!

Mike Sokol

I’ll do an update tomorrow.

Mike Sokol
Mike Sokol

I’ll look through the list a little later today, but I really like the ceramic element heaters since they use a special ceramic heating element that will draw less current the hotter it gets. So you can throw a blanket over them and they still won’t overheat. Of course, there’s no way they can react to an overheated outlet or surge strip, so you still must be on guard for that fire source.