So many homes, garages, basements, and trailers these days incorporate electric portable space heaters, to provide temporary spot warmth during particularly cold nights, or when the grandkids come to stay in that frigid guest bedroom. The typical electric space heater is convenient, in that it requires no installation (unlike gas heaters) and usually no special wiring. It is inexpensive, as many models can be bought for under fifty dollars. It can be moved from room to room, as needed, and often features thermostats for automatic room temperature control, and heat output levels for small, medium, and large spaces. Typically featuring either radiant or convection style operation, portable electric heaters are generally lightweight, and offer some sort of overheating protection as well as three prongs on the AC plug for added protection against electrical shock. But nonetheless, much property damage, burns, and electrocutions involving these heaters occur every year, and some of these are due to faulty or inadequate electric heater design, in which insufficient forethought was obvious in the heater’s construction. So in this article, we explain some of the many safety features found on today’s units, how to identify them, and which ones you should insist on when buying this type of heater, to keep yourself and family safe.
Ideal Safety Features
- Thick, short cord. Look for a heavy yet flexible power cord; #16 heater cord minimum, and preferably, #14. It should be short as well. We recommend four feet or shorter, to minimize the chances that someone will trip over it. Shorter cables also tend to be run less under carpets and other places where people are likely to walk around often, step on them, and damage them. Further, minimum length cords offer less voltage drop due to their lower resistances than the longer wires. So the heater runs hotter and better and more safely with the shortest possible cord.
- No exposed metal parts. Most heaters today are fabricated from plastics and other non conductive materials. However, some feature enclosures constructed of unpainted / uninsulated metals. Even when the case itself may be a good electrical and thermal insulator, the knobs and screws may still be metallic, and electrically connected to the power line inside. Or, they can become too hot to safely touch. For this type of heater, the next safety item is paramount — that it have a three-prong plug.
- Three prong plug. The third prong, the grounding prong, is typically connected to the heater’s metal case, and to any exposed metal parts. This holds them at ground potential, and prevents them from becoming HOT or LIVE should some internal wiring or circuitry fail. Should a fault develop inside the heater, the mains circuit breaker or fuse will blow, as excess short-out current flows through the third conductor to ground.
- Thermostatically controlled. The heater should have at least a basic thermostat that enables it to sense room temperature and turn itself off when the space reaches the desired warmth, to avoid wasting energy due to heating the room too much. Avoid heaters that by design, run all the time, as these tend to fail more often, and do not respond to changing room conditions, such as the temperatures outside warming or cooling.
- Optional timer shutoff. Some of the more extravagant units have a built-in timer, like a sleep timer on a clock radio for example, that shuts off the heater after a set time has elapsed. While this is helpful in situations where you must ensure that the heater does not operate unattended, it should have a bypass position, that allows untimed heater operation for those situations where you require 24 X 7 heating.
- Protection against over heating. A thermal fuse is an electrical device that is wired in series with the internal heating elements. It “blows out,” should the internal heater temperature exceed the manufacturer’s maximum safe temperature specification. This can happen when the vents are accidently blocked or become clogged with dust. A thermal fuse is a one-use device. Once it blows, it must be replaced. This can be difficult for the typical consumer without any electrical background. So we suggest buying heaters with more advanced heat sensors that trip out when overheated, and can be reset via the push of a button.
- Tip switch. Tip-over protection is essential for lowering risks of fire, should the heater be knocked over while operating. The tip switch shuts down the heating elements should the portable heater fall or be positioned on its side or top. Heaters should always be placed with their feet on the floor.
- Large foot print. The heater should not tip or fall over easily, and widely spaced legs and feet help ensure this. Avoid overly tall heaters, where the height is more than twice the shortest distance between their feet.
- Not too light. Heaters that weight too little can be too-easily knocked over. So a little weightiness can enhance their stability. However, a larger foot print, as discussed above, can offset a heater’s feather lightness.
- No exposed heated metal. Any metal components that support or otherwise come into direct or close-proximity contact with the heating elements should not be easy to touch during heater operation. They should be completely encased by the heater’s insulated enclosures to prevent burns.
- No touchable heating elements. The heating element should be positioned well inside the case so that no curious fingers can reach through openings and vents, and get at it. We recommend that the element should be no closer than three inches to any opening to the outside of the case.
- Cool exterior casing. Nowhere on the heater case should temperatures exceed lukewarm values (cool touch).
- Avoid cheap heaters with fans. While a fan, blowing the heated air around may heat a room more quickly and uniformly, fans are noisy, often fail, and because they constantly draw air in and out of the heater during operation, the interiors of these units tend to get dusty and dirty quickly, which can cause premature failure of other components inside. We opt instead for the gentle, silent heater types like the sealed water-filled radiator units, which last virtually forever, are very quiet, and require low to no maintenance.
- Maximum power draw at 120 volts, of 1875 watts or 15 Amps. Typically the maximum heating power for portable space heaters is limited to 1875 watts, so that they can be safely deployed in a wide variety of typical home heating and circuit wiring situations. If you require more heat than this in a particular space, then we recommend foregoing the portable, and installing a higher power permanent heating unit, such as an electric baseboard heater.
- Water filled, not oil filled. Though this occurs rarely these days, oil filled heaters can develop leaks. Then you have a slick to clean up from your carpets, hard wood, or concrete floors. Plus, the internal elements may overheat and catch fire as the leaking oil recedes from them, and taking its cooling effect along with it. Further, water filled heaters heat just as well as the oil filled ones, but do not damage surfaces (beyond water damage) should they eventually leak. Plus, they’re easier to dispose of safely.
- No visibly glowing heating elements exposed. Admittedly, heaters that do not glow have the disadvantage of being larger on the whole than those that do. So this safety feature can be difficult to avoid if you have very little space. They also tend to have hotter external surfaces, and so, are more likely to cause burns should someone touch them. Bigger heating elements are safer because they distribute the same amount of heat over a larger area, and so need not run as hot in order to generate equivalent heat. Thus, they do not glow. Plus, the cooler the heating element runs, the less likely that it will ignite any combustible materials or fumes that might be nearby in some environments. So we recommend that unless you have a specific heating requirement that can only be met by a “glowing element” style electric heater, then avoid these where possible.
- Ground fault protection. Many portable electric space heaters feature an integrated ground fault interrupter circuit (GFIC) in their plugs that resembles those “wall wart” transformer plugs found on many low power electronics. They have two buttons; one for forcibly tripping the GFIC for test purposes, and the other to reset it (turn it back on). This adds a level of protection against electrical shocks; particularly when the heater is used in bathrooms that have no GFIC outlets, or other potentially wet locations such as garages and basements.
- Over current protection. The safest heaters also include a circuit breaker or fuse built into either the wall plug assembly, or into the heater case itself for easy access. This guards against overheating due to shorts or low-resistance paths that can develop inside these heaters over time due to accumulations of electrically conductive dust inside. Not only will this usually prevent fires from this cause, but the breaker tripping reminds you that it might be time to either thoroughly clean the heater, or replace it.
- Designed for easy cleaning. Look for lots of vents, located so that they can be vacuumed out periodically without too much effort. The heater should feature a minimum number of similar screws for easy disassembly for cleaning its deep interior crevices.
- Wet design for wet locations. Do not use an electric space heater in a damp or wet location, unless its instructions specifically state that it was designed to operate in such environments.
- Underwriters Laboratory (UL) Approved label. Never buy a heater that has not been tested and verified safe by Underwriters Laboratory or similar organization like ETL or CSA. They generally will not approve a particular heater unless it incorporates most of the previously listed safety features.
While electric space heaters cost more energy dollars to operate, they are by far the safer units, when compared with natural gas, kerosene, and propane heaters. They emit virtually no fumes, require no external ventilation, offer no risks of spilled fuels, carbon monoxide poisoning, and generally, electric heaters operate virtually silent and maintenance free for many years. They de-centralize the heating task, which facilitates room-by-room temperature control. Their purchase price is very low compared with furnaces and combustion type space heaters. You can thus, buy as many as you need and place them in each room, where each can be set to a different temperature. This allows for not heating rooms where heat is not needed, which can significantly cut energy costs. Electric space heaters, over their lifetime, probably cost more over all. But they offer perhaps the safest portable heat sources available. You get what you pay for.
- 2015-01-18: Added more appropriate tags.
- 2015-10-23: Added appropriate tags.
- 2015-08-18: Originally published.