Wednesday, February 8, 2023


RVelectricity – Just Ask Mike (J.A.M.): Electric space heater tragedy in an RV

By Mike Sokol
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) with the subject line – JAM. This week I discuss the dangers of portable electric space heaters and extension cords.


Dear Readers,
Time for another reminder about the dangers of portable electric space heaters and extension cords. Read this sad story from Sunday’s News for RVers newsletter below, then let’s discuss what likely happened and how to avoid a similar tragedy.

Firefighters in Tillamook, Oregon, provide a sad footnote from an RV fire on May 21.

Crews arrived at the Tillamook Coast RV Park four minutes after receiving a call about a fire. On arrival, they found other RVers hustling away fuel cans from the scene, and trying to hold back the flames with a garden hose. Douglas James Schoniger (40) of Tillamook died in the fire.

Investigators found the cause: A 100’ extension cord was coiled up and lying under a stack of clothing and other combustibles inside the rig. The cord was being used to power an electric space heater, and the heater’s demand far exceeded the ability of the cord. Additionally, there was no working smoke detector in the rig. One investigator noted that he had the power to inspect businesses for hazards like these, and help ensure corrections. In the case of private residences, he can only hope people take care of their own safety.

It’s me again…

As I’ve noted many times before, a portable electric space heater produces a huge, continuous load on any outlet it’s plugged into. Now, if the outlet is well maintained and all connections properly tightened it should be safe. However, if you allow the contacts to become oxidized (corroded) or any of the terminating screws to loosen, then there’s a high resistance point created that can easily overheat under load. You’ve probably seen the pictures of burnt outlets I’ve posted here many times.

A recipe for disaster!

But this fire was a little different. It appears to have been caused by a 100-foot lightweight extension cord that the space heater was plugged into, coiled up under a pile of flammable clothing and other combustibles. Also note that there was no working smoke detector in his RV.

This, quite simply, is a recipe for disaster. And indeed, it resulted in the death of Douglas James Schoniger.

What happened?

Here’s a video I did a few years ago demonstrating how hot an extension cord will get when it passes twice its rated current. In it the insulation temperature reached 190 degrees F in 5 minutes, and would have gotten hot enough to catch on fire in just a few more minutes. An extension cord buried under combustible materials will get even hotter from lack of air flow. So, a few hours of overheating is almost a guarantee that a fire will start under these conditions. Watch the video HERE.

In Review….

What you need to know to help prevent another tragedy like this one

  • NEVER plug any electric space heater into a lightweight or long extension cord. If you do need to use an extension cord, only use a short, heavyweight cord rated for air conditioners (like this one).
  • DON’T plug an electric space heater into a power strip. That’s a sure fire hazard.
  • ALWAYS keep all flammable materials (clothing, newspapers, etc.) away from all electrical cords and outlets.
  • MAKE SURE you have operating smoke and CO detectors in your RV, as well as your bricks and sticks residence.

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 For more info on Mike’s qualifications as an electrical expert, click here.
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Hook n' Haul 789
1 year ago

I’ll add another cause of space heater tragedies. While serving as a Volunteer Firefighter my Engine Company responded about 2:00 AM to a mobile home fire in a rural area. The fire was well advanced by the time the 1st company arrived. We lost 5 children ages 9 mos. to 12 yrs. A 16 year old survived. It was later determined that a space heater was situated too close to bedding in the bedroom. KEEP ANY HEATER, ELECTRIC,OR OTHERWISE, AT LEAST 3 FEET FROM COMBUSTABLES – FURTHER IF POSSIBLE. 20+ years later but I still can’t forget that night.

RV Staff
1 year ago

What a horrible tragedy, Hook n’ Haul 789. Thank you for the important reminder. Take care. 🙂 —Diane

1 year ago

I also think some people under-estimate how hot electric heaters get. Even the tiny Lasco ceramic heaters that seem ubiquitous in the RV world throw enough heat to melt a plastic Soda Stream bottle accidentally set ten inches in front of the heater. (Ask me how I know. . .) I would never fall asleep or leave the rig with an electric heater on and am super careful where I place my heater when I’m using it.

1 year ago

Another option is if you are really set on using Electric Heat over your gas is to use the RV Comfort Systems Hybrid Gas/Electric furnace system. It is spacifically designed for RV’s plus its UL Listed and RVIA compliant.

Last edited 1 year ago by LARRY MCGAUGH
1 year ago

I had a cord reel that allowed you to use it without unspooling all 50′ of the cord. One time I went to unwind it and couldn’t because the outside insulation had melted then cooled and fused together.

I don’t think that it ever had a heavy load but the cord in the middle couldn’t dissipate much heat with several layers of cord on all sides.

Thom R
1 year ago
Reply to  Irv

I was pressure washing my siding last year, had a similar experience. Extension cord was partially coiled up, it got hotter than I could hold in my hand. What an eye opener! Big lesson learned. I will never bring an extension cord inside our RV!

1 year ago

In addition to the resistance heating in an undersized extension cord, since this article reports that the cord was coiled, would induction within the coil contribute to heating? Or does the current in the neutral wire effectively offset the field from the hot wire?
To mitigate induction losses, I typically uncoil extension cords while in use.

Mike Sokol
1 year ago
Reply to  Robert

No, inductive heating didn’t contribute to this. First of all, as you noted the neutral and hot conductors laying next to each other would cancel out any inductance. And even if it was an isolated/single conductor, the reactance of this coil or wire at 60Hz is so little as to be negligible.

1 year ago

An extension cord is for temporary use only, if you need to use it for extended time then you should install a receptacle. About a month ago I did just that and installed an additional outlet for the coffee maker so I could do away with a short extension cord. I am not a fan of power strips and put them in the same category as extension cords, many have been recalled over the years due to fire, in 2013 15 million APC SurgeArrest surge protectors were recalled due to fire hazard. If you use a power strip just Google The make and model to find out if yours are on the list.

keep up the good work Mike

1 year ago

Another excellent article! As a retired electronics engineer and Asst. Fire Chief and Arson Investigator the improper use of extension cords is a recipe for disaster! Extension cords (and power strips!) are a great tools, but they need to be sized and used properly!

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