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.
Close to home
In 2017, 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. Her co-workers said the victim used electric space heaters extensively in her house. She must have had a few close calls (small fires?) since everyone seemed to be worried about her using them to heat her house. The fire inspector reported that she had a portable electric space heater plugged into a string of outlet strips, and the wiring was covered in old newspapers. That’s a sure recipe for disaster.
Are electric space heaters really dangerous? Well, don’t just take my word for it. Here’s what safeelectricity.org says about them.
Why do we use them
Portable 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. These heaters cause at least 25,000 home fires a year, along with 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 (NFPA).
Are they dangerous?
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 (or V x I on this Ohm’s Law chart). That suggests we can divide the wattage of the appliance by the voltage and find out how many amps it draws.
Here are the numbers
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 a properly installed and maintained electrical outlet should be able to sustain that amount of current indefinitely, few home (or RV) owners do routine inspection and maintenance of their electrical outlets.
If you do draw 15 to 20 amps continuously from an outlet, it can begin to heat up. That heating will soon cause the electrical 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 eventually 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.
Danger, Will Robinson….
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 a 12-gauge cord is way better. 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.
Doing it safely
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 or a 1,500 watt heater set on 750 watts 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 if properly installed. 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 current path to overheat.
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. Also, I think that anyone installing a permanent electric heating system should consider upgrading their twist-lock shore power inlet to a SmartPlug, which has 20 times the contact area of an RV traditional twist-lock inlet.
A 10-second poll
Please take this short poll showing if you use a portable space heater in your RV. (It may take a few moments for the poll to load.)
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 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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