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For problems with most other wiring, circuits, and connections, be sure to see my Main pages. This page is specifically about particular devices, outlets, and appliances whose features have implications for troubleshooting. For basic wiring see this page.
2-hole receptacles. Electrical boxes were commonly provided with grounding wires only beginning in the mid-1960s. But over the years, many homes built before then have been given ground-type receptacles (3-holes) in order to physically accommodate 3-prong cords. Unless new cables or ground wires were run to these outlets, however, these receptacles are lying, seeming to promise grounding when there is none. And the simple 3-hole outlet tester used by home inspectors at the time of a home being sold will reveal this. Such outlets must either revert to having 2-slot receptacles (still available and legal for that situation) or be given grounding (a wire back to the panel from each circuit being grounded) or be protected by a ground-fault interrupter (though this won't help surge protector strips do their job).
Two-prong to 3-prong adapters (commonly gray) usually do nothing more than allow you to plug a 3-prong cord in; they still lie about the grounding. The exception is if the metal box was grounded even though the installed receptacle was one with only two slots. This was done briefly in the early 1960s or so. The way to tell if such a box is grounded is if it will run a light bulb (in a socket with wires) from the hot slot to the box.
Arc-fault interrupters (AFCI). New with the 2002 Code, these special circuit breakers with an extra colored button (similar to those on a GFCI breaker) are able to identify and trip for a kind of arcing (at cords, outlets and lights) that has caused some fires. With the 2008 Code, most rooms in a home must have this protection. AFCIs are made with GFCI-type protection built into them as well. So these AFCIs are liable to complicate the troubleshooting process. The tripping of a normal breaker already presents us with several possibilities: short, overload, or the breaker's connections overheating. An AFCI could trip for these same things plus for a ground-fault or an arc-fault. As long as it keeps tripping for the troubleshooter, which cause is at work and where it is happening will be possible to determine by different tests. But if it repeats tripping only intermittently, good luck. If you contact me, we could strategize about such a case. Also see AFCI breakers.
Dimmer switches. A dimmer saves some electricity and bulb-life. Dimmers normally produce some heat when operating [my rule of thumb is that if you can keep your thumb on the cover-plate screw without fear of getting burned, this is normal]. Unless rated to handle more than the usual 600 watts, a dimmer controlling more than 600 watts of lighting will get hotter than it is designed for, will not last long, and could present fire hazard in some conditions. Most dimmers have electronic components that are vulnerable to surges. My experience suggests that fancier dimmers that display their setting level or that stand ready to respond to the simple touch of a finger are even more likely to be damaged, from a surge or from a light bulb burning out. Specially rated dimmers are needed for low voltage bulbs; none are meant for normal fluorescent bulbs/tubes/fixtures.
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).
Doorbells. The most common doorbell system in homes runs on 12-16 volts and consists of a pushbutton, a transformer, and the chime itself. These are wired in relation to one another with 18-22 gauge bellwire, thermostat wire, or phone wire; only two wires are usually needed between these components. In the 1940s through 1960s it was common for the chime to be able to ring differently for front and back doors, and so two pushbuttons were wired. More recently electronic chimes have become available; they may need a stronger transformer and/or more wires. Among the problems that can develop are a sticky chime-plunger or pushbutton, a burned out transformer, and of course loose wires.
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.
Generator switches =Transfer switches. These panels or switchboxes are meant to make powering some of a home by generator foolproof. Rigging your own way of interfacing the two power sources is virtually illegal. The switching setup varies with the size of generator and the number and size of circuits to be potentially run by the generator. Some even operate automatically when an outage hits, starting the generator in the process. In the cases I am aware of, either individual circuits, a subpanel of circuits, or an entire main panel are fed power through the switch(es) from either the local utility or from the generator. So even normal power on a mild day has to pass through the switch(es) to reach the circuit(s). This means that a transfer switch that is turned or knocked off unknowingly will disrupt some power on a day no one is thinking about the generator. Since people are trained to check, at the most, breakers and GFIs when they lose power somewhere in the house, the generator box gets overlooked.
Two other little problems show up if one of the circuits run by the generator has a GFCI circuit breaker in the main panel and there is a transfer switch for that individual circuit. First of all, when the circuit is using generator power, it will not be protected from ground-faults, because that GFI device is now isolated from the circuit. But secondly, when utility power comes on while the generator is still running this circuit, the GFI breaker in the main panel, being now energized, will be able to sense if some load current is on the neutral wire (which is not isolated) and will notice that none is yet flowing on its hot wire (which is still isolated from the circuit). Since that would constitute an imbalance, the GFI breaker in the panel would trip, so that when you transferred everything back to utility power, suddenly the circuit in question would not be working and you would have to reset the breaker. But no harm done. All of this would also be true of many of the new arc-fault breakers, the ones that incorporate ground-fault protection as well.
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 only 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.
Light bulbs. Since they are so basic to us, light bulbs can also be a headache. They burn out, they come in too great a variety, and they can even damage some kinds of switches.
Light fixtures with standard sockets will accept a standard pear-shaped bulb of almost any wattage, but most fixtures are only designed to handle the heat of 60-watt bulbs or less. Anyone unaware of this is likely to replace burned out bulbs with hotter ones, either accidentally or in order to get more light. This will tend to slowly cook the fixture and the nearby ceiling -- not a good idea. Running a bulb with too high a wattage can also make a recessed light turn itself off and later back on. This is from a built-in feature meant to prevent exactly the cooking I mention.
The wattage of bulbs also needs to be limited when they are to be controlled by dimmers or motion sensors. The common limits for these are 600 watts and 300 watts respectively (total watts of all bulbs being controlled) . Any dimmer switch will always produce some noticeable heat in itself when operating, but a dimmer running too many watts will be extremely hot.
There are a variety of reasons that bulbs will burn out too soon. When the fixtures containing them cannot dissipate their heat (as mentioned above), it takes a toll on the bulbs. If the lights are ones that are left on a lot -- like outdoor lights left on all night -- then the bulbs may be living their full life but will simply have to be changed more often than others. But other things can contribute to early failure. Bulbs may be of cheap quality. Or there may be loose, arcing connections in the socket or in the wiring of the circuit.
The life expectancy of a bulb will also be affected by the quality of power from the power company. This includes the little surges and spikes that are better known for their effect on computers. But it also includes the basic voltage level coming to the home from the utility. Many homes receive more than the average 120 volts that most bulbs are designed to handle, and this shortens their stated life. A good solution to this is to look for the same bulb but with a "130v" rating stamped on the bulb instead of "120v". The light output of these won’t be quite as bright, but you will spend less of your time getting the ladder or stool out again.
Besides these incandescent bulbs, fluorescent bulbs and tubes are common. Replacing the straight fluorescent tubes can be tricky. If they don’t twist into place right, they won’t work right. On the other hand, twisting too forcefully can break an end socket. If the fixture has two or more tubes and isn’t working very well, it is best to replace them all with brand new ones (from the store is more reliable than from the shelf). The tubes work in pairs, so that if one of the two tubes is bad, neither will work well. This is one reason it is simpler to get all new. The other reason is that tubes will tend to die around the same time as each other anyway.
Compact fluorescent bulbs that screw into a standard socket are good energy-savers. However, they have a limitation that is not well known. Most dimmer switches and most electronic timers are not designed to work with these bulbs. These special switches will meet or dish out an early death if they try.
One phenomenon that can occur with compact fluorescents is this. Though turned off, if these bulbs are controlled by a lighted switch, a small pulse of light may be visible every minute or so, especially in a dark room. This is due to how the lighted switch needs to run a little current through the bulbs.
Visit this site for More on light bulbs.
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.
Motion sensors. Lights that have a motion sensor to switch them typically have the following features. Motion is sensed from the heat emitted by people, animals or cars within the field of view of the device. They also sense light so as to prevent operation during daylight (this feature can be bypassed when using a "test" mode). There are usually settings for how sensitive you want them to be (equivalent to the distance away it will sense motion, I believe). There is also a setting for how long they keep the light on after motion is sensed or after motion stops.
So when a problem arises with a motion activated light, check all these settings and of course the light bulbs themselves. One common feature is that a brief interruption of power to the sensor light (and you can do this purposely) may program it to stay on indefinitely or at least till the next dawn. To escape this mode usually involves turning power off for a longer time before restoring power.
Being electronic (and some being cheap), motion sensors die, often within five or ten years. The sensor part may be replaceable, but whole fixtures that incorporate sensors are very common, and many are cheaper than a separate sensor.
Photocells = photoelectric cells = photoelectric eyes. Some, but not all, photocells, which turn lights on at dusk and off at dawn, are rated to control quite a few lights, including fluorescent. When they fail, the result is commonly that their lights stay on all the time. Of course, if shrubbery has overgrown the area of the photocell or if paint or algae has accumulated on its "window", then the lights could be staying on or staying on later into the morning for these reasons.
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.
Receptacles. ="Plug-in" ="Outlet". A home’s "plug-in" outlets are termed "receptacles". They do a lot of slave labor for us, so that we take them for granted -- until they give us trouble, like many electrical items.
It helps to distinguish localized trouble from system trouble. If a receptacle, or even a few in different parts of the home, have occasional trouble running things, and this is affected by manipulating the cord-end as it is plugged in or out, the receptacle is probably worn out. By this I mean that the receptacle’s springy receivers, which hold on to the prongs of the cord being plugged in, are bent or "sprung" from multiple use or abuse. This is very common at receptacles that are out in the open in a room or hall, that is, where the vacuum cleaner is often used. When the vacuum cord is stretched to its limit, it will be pulling (sideways) on the receivers, bending them. To bend a cord’s own prongs to match is a poor stop-gap solution. Such receptacles need replacement.
On the other hand, if the outage is solid, long-lasting, and affects other outlets in the same area, it has something to do with the electrical system. The simplest possibilities include a tripped breaker or ground-fault interrupter (GFCI). Resetting a GFCI involves pushing its reset button in. (Finding the right GFCI is another matter). A tripped circuit breaker is reset by first turning it very firmly off, then on. If it wants to retrip quickly, a short circuit is happening. I will mention one origin of short circuits because it has to do with receptacles. If the screw that holds the coverplate to a receptacle is longer than usual, it can break the receptacle apart internally and set up a short.
Beyond these, a system outage will be from a poor connection somewhere along the circuit. The problem’s location will occasionally show itself as a browning or discoloration visible on the face of the receptacle or its cover -- signs of heat damage. If not, see Outage. If heat itself is felt at a receptacle, this can also be a sign that a connection is in trouble and about to give up. However, heat and browning will sometimes have to do with a particular heavy load -- a space heater, for instance -- that has been used at the particular receptacle. That would fall back in the "localized trouble" category. In either case, that receptacle would need to be replaced and its wire connections improved.
Smoke alarms. If a smoke alarm is "direct wired" (whether it has a battery as backup in addition or not), it will often also be interconnected with other smoke alarms in the home by means of a third insulated wire (usually red in the house-wiring and yellow or orange from the alarm); the black and white wires of the alarm are to attach to black and white wires of the home's electrical system. When there is such interconnection, it can be hard to determine which alarm is setting all of them off, and one alarm may not be replaceable except with an alarm of the exact same brand and model; so replacing all at once may be necessary. When alarms include batteries, they may sound a signal of some sort to warn you that the battery is low.
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.
Switched outlets. By code most rooms must have a light, which is to be controlled by a wall-switch. Since home designers may want the appearance and placement of lights to be versatile, plug-in receptacles for portable lamps in living, family, and bed rooms etc. are allowed to be what is switched, rather than a permanent fixture.
In the 1950s and 1960s an entire outlet or two in these rooms might be switched. Since then it has been more common to switch just the top or bottom half of our usual "duplex" receptacles. This has been made possible by the fact that the top and bottom halves of modern receptacles are electrically connected by two accessible and removable metal tabs to the right and left of the center of an upright-mounted receptacle. See examples in my Tour of a Circuit or Connections tutorial.
For only half of such a receptacle to be switched, the tab on the hot (black or red) side must be broken off by bending it back and forth several times. The wire that is made hot by the switch is connected at the receptacle to a hot-side terminal on the top (or bottom) half, with wires that are to be always hot connected on the other half. The neutral (white) wires are all connected anywhere on the "white" side of the receptacle, and the tab on that side is left in place. Any wire (usually red) that is supposed to go on to another receptacle in the room to switch half of it as well, needs to connect to the hot side on the same half as the one made hot by the switch.
If receptacles have recently been replaced in a room, and the switch for the room no longer turns any receptacle off, then hot-side tabs have probably not been removed from those new receptacles that were replacing old ones which had been switched. The presence of a red (switching) wire attached to a new receptacle will tend to mean it had been switched before. If all the hot-side tabs at such places in the room are not broken off, the switch will not be able to turn lamps off anymore at any of those spots.
Thermostats. Zonal electric heat provides thermostatic control for each heated area. Typically, these "stats" are factory calibrated so that the temperature settings stated on them correspond to the actual temperature they will maintain in the room. There will still be a lag of two or three degrees as the heater continues working before its heat has had a chance to affect the stat, or as the heater waits to come on because the coolness of the room air has not yet affected the stat to turn it on. People not familiar with such small but noticeable "swings" sometimes try to compensate for this by turning the stat way up or down, thinking the extreme settings will make things happen faster. They won’t.
There are two ways that a thermostat can be inaccurate. One is that its calibration from the factory or over time has become five or even ten degrees off from the truth. Most stats have a small setscrew (painted in place so it won't move) that can readjust the calibration (judged by where the clicking sound occurs around the dial). However, many people are happy to ignore the strict temperatures stated on the stat and simply remember a setting that feels comfortable to them, perhaps marking this with a pencil.
The other inaccuracy of a thermostat is more extreme. This would be when its control of heat is either wildly erratic or occurs, if at all, only at the very low end of the scale -- the room definitely overheats. This tends to mean the thermostat is on its death bed.
Some large living room areas use a low-voltage thermostat in conjunction with a relay. Calibration and "swing" problems for these can usually be addressed at the stat, whereas complete loss of control will mean the relay is bad. (Good luck finding and recognizing the relay.)
The hookup of thermostats may present problems. Manufacturers of 240-volt thermostats indicate which of their wires is to attach to the incoming line wire(s) and which to the outgoing load wire(s). I am not aware that the reversing of these makes any operational difference. What can get confusing, however, is the hookup of a 2-pole thermostat, especially where it is replacing a single-pole thermostat (or vice versa). If the one or two cable-pairs of wires that go to the heater(s) are connected to the wires marked "load" and the one or two cable-pairs of wires bringing or sending on the constant incoming voltage are attached to the "line" wires, then things should work. But suppose you are replacing a single-pole stat and brought a double-pole home from the store. Yes, you can attach just one side of the double stat to the two (black) wires you unhooked the old stat from, but it matters which side of the double-pole stat you use. This is because almost all double-pole thermostats are fake. By this I mean one half is a normal single pole stat, but the other is only set up as an on/off switch, not heat related. So if you were to hook to the on/off side only, the stat would only act like a switch (always on till you clicked it off at the very bottom end).
Timers. Here I am referring to switches that mount in normal electrical boxes and control what time of day (outdoor) lights will turn on and off. Some are completely mechanical, having a motor that turns a clock past on-off trippers; these are actually the most reliable. Others are electronic and are usually more limited in the total wattage and type of bulb (incandescent) they can control; some won't even work or give a read-out if the bulbs are all burned out. Electronic timers are shorter-lived, being vulnerable to surges and lightning.
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.
X-10 switching. This high-tech type of switching is used with "smart homes", which are able (even remotely) to program lights and appliances to operate as commanded. If the people who inherit such a system are not as "smart" as it is, this technology may be not so smart after all. In any case, I have not had much call to trouble shoot these systems, but others (esp. the manufacturers' and retailers' representatives) have. If you think you have such a system, I recommend you check these sites: smarthome and mentor.
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