By Mike Sokol
This is a special two-part article on a topic that’s not only seasonal, it’s very important to your safety, both in your home and your RV. This is about electric space heaters and how dangerous they can be if not used correctly. Be sure to answer the poll at the bottom of this story where we ask about whether you do or do not use a space heater in your RV.
Just a week ago in Hagerstown, MD, (my town, in fact) there was a house fire around 3 a.m. which resulted in the death of a mother and her adult son. The fire inspector is still investigating the exact cause, but her co-workers said she used electric space heaters extensively in her house. She must have had a few close calls (small fires?) since everyone was worried about her using them to heat her house.
Are electric space heaters really dangerous? Well, don’t just take my word for it. Here’s what safeelectricity.org says about them.
Space heaters can be a quick way to heat up a room. However, they can be as dangerous as they are convenient if used improperly. Space heaters cause 25,000 home fires a year, and 6,000 emergency room visits, according to the Harvard University Environmental Health & Safety group.
Approximately one-third of all house fires nationwide happen during the cold home-heating months between December and February. Equipment that is intended to add a little extra warmth, such as space heaters, is the leading cause of these fires, according to the National Fire Protection Association (NFPE).
So, exactly what can go wrong with an electric space heater that makes them so dangerous, especially in a confined space like an RV? In Part 1, this week, I’ll discuss the issues of current draw and in Part 2, next week, we’ll delve into flammable material issues.
It’s all about the watts, and the amperage needed to make those watts happen. If you remember some of the electrical math I’ve used in the past, wattage is simply volts times amperes. That suggests we can divide the wattage of the appliance by the voltage and find out how many amps it draws.
A 1,500-watt space heater on a 120-volt outlet is 1,500/120 = 12.5 amperes. And an 1,800-watt space heater works out to 1,800/120 = 15 amperes. And while that’s a 20-amp circuit, in reality the electrical code originally designed that outlet for 15 amps of current, and assumed you would be drawing maybe 10 amps each on two separate outlets on a single 20-amp circuit breaker.
If you really do draw 15 to 20 amps continuously from an outlet, it will begin to heat up. That heating will cause the outlet contacts to oxidize and increase their resistance. And that resistance will increase the heating effect, which causes more resistance, which leads to something we engineers call cascade failure. That can result in a char around the outlet itself and a potential fire. How to know if this is happening? If the outlet your space heater is plugged into feels warm to the touch or has any dark marks around it, then the outlet contacts have been overheated and it should be replaced.
Importantly, NEVER run any electric space heater from an extension cord, especially a light-gauge one. Anything that draws 15 amps continuously needs at least a 14-gauge extension cord, and possibly a 12-gauge cord to be totally safe. That’s a really heavy extension cord for that little space heater. And never put two space heaters on a single outlet or extension cord. As you can see in my video, an overloaded extension cord can reach the boiling point of water easily.
So what can we do to avoid electrical outlet overload and heat our RVs safely with electricity? First, if you need to use any space heater at all, use it on a low-wattage setting. I think that a 1,200-watt space heater is the largest I would use on a conventional electrical outlet, and even then it shouldn’t be run unattended. And make sure your smoke detectors are operational.
Second, if you really need that much electrical heat (and it’s certainly cheaper than heating with propane you pay for yourself), then the CheapHeat product is a safe and effective solution. The CheapHeat system is specially designed to be able to run continuously as part of your RV’s furnace, and since it’s hard-wired into your circuit panel there’s no electrical outlet in the path to overheat.
So do campgrounds actually welcome the use of the CheapHeat furnace system? At first blush you may think not, since it does cost them more in their monthly electric bill compared to everyone heating with propane. However, they really DON’T like electric space heaters simply due to the risk of fire. So if you plan to heat your RV electrically, then do it correctly with a hard-wired heating system that’s designed from scratch for the job.
Join me next week for Part 2, where I’ll discuss various technologies for space heaters including coil, ceramic and oil filled. Are any of these technologies more efficient or safer than the others? Tune in next week.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit NoShockZone.org for more electrical safety tips. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.