The Circuit Detective    -  Appliances' Circuits

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Appliance Problems Can Be Circuit Problems


For problems with most other wiring, circuits, and connections, be sure to see my Main pages. This page is about some specific appliances whose features have implications for troubleshooting them or their circuits. Two similar pages address some specific Devices and Controls (automatic switching devices).

Disposals
Dryers
Hairdryers
Hot tubs
Microwaves
Ranges
Spaceheaters
Water heaters

Disposals. A garbage disposal is usually given its own circuit. Occasionally it may share with a compactor or dishwasher, or (in older homes) with a nearby kitchen outlet circuit. A disposal that runs all the time regardless of its switch may have been plugged into the wrong half of a double receptacle under the sink. A disposal that hums when turned on, but doesn't turn, is probably jammed. If it doesn't hum or turn, the breaker could be tripped or a (red) button on the appliance may need to be pushed to reset it (it tripped to protect the motor from overheating, from a jam perhaps).

Dryers. Most all-electric clothes dryers use 240 volts to power their heating element and usually 120 volts for turning the drum and blowing the air through. So sometimes when it seems as though the heating element must be burned out, it is actually one of the dryer's two fuses or half of its double breaker that is blown, tripped, or having connection trouble. Don't automatically get a new dryer.

Another question I get about the dryer is the type of receptacle and cord that is appropriate. In general, an existing 3-hole dryer receptacle should not be replaced with 4-hole dryer receptacle because there will not usually be a fourth (ground) wire in that box. A 3-prong dryer cord should be installed from the dryer for an existing 3-hole receptacle and a 4-prong dryer cord for an existing 4-hole receptacle. In the dryer a metal strap at the neutral (center) terminal should be connected to the frame of the dryer when the cord is 3-prong and should be disconnected from the frame or from neutral for a 4-prong cord (whose green 4th wire connects to the frame).

Recently household dryers have become available which run 26 amps along the circuit, rather than the usual 21 or 22. This may cause the 30-amp breaker which did fine with a previous dryer to trip for one of these new ones (after a few minutes of operation). True, a 30-amp breaker should be able to handle the load, but any imperfection in the contacts or wire connection of the breaker, or even its closeness to other warm breakers, will produce more breaker-tripping heat, due to the higher current being run through it.

Hairdryers. When Code began requiring a dedicated 20-amp circuit for bathroom outlets (1996), U.S. hairdryer manufacturers largely began selling 1800 watt (15-amp) hairdryers almost exclusively. This was fine for homes built since then, but most homes built before that still have 15-amp circuits serving those receptacles, often shared by lights and other outlets in the area. Thus overloads that trip the circuit breaker are perhaps even more common from hairdryer use than used to be the case. Since lower-watt hairdryers cannot generally be found, unless you can run yours on a lower-watt setting, the best solution is to have a new dedicated 20-amp circuit run to such receptacles. GFI protection must also be provided for such new bathroom outlets.

Hot tubs. In the National Electrical Code hot tubs fall in the same category as swimming pools and are subject to extra safety provisions, since water, electricity, and people don't mix well. One of these requirements (since the 1990s) is that the entire electric line feeding to the tub be protected by a ground-fault interrupter. It is commonly a special 240/120 volt circuit breaker that trips off for an electrical leak as small as 5 one-thousandths of an amp. If this breaker only trips when a certain component of the tub is turning on, it is likely that part of the equipment that is faulty. If the breaker has never stayed on from when it was installed, the chances of its being defective are still not as great as its having been hooked up incorrectly, nor as great as the tub's having a basic ground-fault somewhere in its equipment. I have found one or two cases where a tub that had sat idle for a month or two would not let the GFI breaker turn it on until after a non-GFI breaker had warmed everything up for a day or so and driven moisture or ghosts out of the tub equipment.

Microwave ovens. Some microwaves on the market use an entire 15 amps when running. This can contribute to a breaker tripping from overload even in new kitchens that are supplied with 20-amp outlet circuits. But a very common tripping situation exists, regardless of the microwave's power, wherever one of these appliances has been mounted over a stove (where an exhaust hood used to be) without providing a stronger circuit for it. The hoods tended to be wired on a general-purpose 15-amp circuit shared with other lights and rooms. Such areas will also often show a noticeable dimming when the microwave runs. The solution to such tripping is to have a new dedicated circuit run for the microwave.

Range (plug-in variety). See Dryer above regarding the right receptacle and cord to use (but use ones for "range" not dryer). Also, like a dryer, the failure of the oven plus a burner or two to heat can sometimes be due to half of the 240-volt power being poorly connected at the cord, receptacle, or breaker/fuse.

Spaceheaters. Home design has always assumed that a residence would be supplied with permanent heating equipment. However, the use of a portable space heater is common where the main heat source is inadequate or where a particular room or person has a need to supplement or control heat individually. But the capacity of circuits for bedrooms rarely anticipates this. These are commonly 15-amp circuits which may extend to carry the electrical load of two additional rooms. So overloading such a circuit (tripping its breaker) is common. The fact that many portable heaters now include a switch for choosing a wattage lower than the usual maximum (1500 watts) doesn't always register with people, especially if they like the way the full wattage warms a cool room up faster. Besides using the lower-watt setting or getting a heater that has this feature, the solution to these overloads would be to run a dedicated circuit to a new receptacle in each room needing zone heat, or to consider running circuits for permanent in-wall or on-wall heaters.

Water heaters. Typical household electric water heaters these days run about 4500 watts through one of two elements at a time. Each element has its own thermostat, whose temperature setting can be adjusted. When the upper element, where hot water first leaves the tank, has achieved the temperature it was set for, its thermostat switches the current down to the lower element to prepare more hot water to replace whatever might be drawn off from the upper part of the tank. If both stats achieve their setting, no more current flows. Of the two stats, the upper one has a reset button that will pop out and keep both stats from running current through their elements; this occurs if water there has gotten extremely hot (usually when one of the stats is stuck on and needs to be replaced). If the water heater itself is fairly new when this happens, it doesn't make sense to have a plumber replace the whole thing when probably only a thermostat is at fault. On the off-chance that the button's popping off was just a one time thing, simply pushing it back in will restore operation.


© 2005-2012 Larry Dimock

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