Knowing how to troubleshoot, isolate and repair electrical problems is what separates the men from the boys-if you’ll excuse the non-politically correct expression-when it comes to electrical work. Almost anyone can install a new receptacle, light switch, light fixture ceiling fan, etc. but being able to determine and repair the problem when they don’t work is an entirely new ball game. In order to effectively troubleshoot you must know how a circuit works. Back in the days when I had my own radio and television repair business we always said that there were two kinds of people in the business-parts changers and technicians. Parts changers were those who changed one part after another until they fixed the problem because they didn’t know how to isolate problem to a given component-resistor, capacitor, IF Transformer, vacuum tube, etc. The technician, on the other hand knew the theory of how each circuit worked and knew how to use the appropriate test instrument to isolate a problem to the component level. Technicians were able to makes repairs in a fraction of the time it took the parts changers and that saved the customer money. They also saved their customers money by not replacing perfectly good parts. Basically diy electricians fall into the same two classes and, hopefully, by the time you finish this factoid you will be well on your way to becoming an electrician and not a parts changer.
All of these test instruments are available at almost any home center, like Lowes or Home Depot.
1.) Digital Multimeter
2.) Clamp-on (Amprobe)
3.) GFCI Receptacle tester
4.) Receptacle polarity tester
5.) Non-contact voltage tester
6.) Circuit breaker tracer
If you buy all these instrument at once you are looking at a $250 o $300 investment but it will be money well spent because you will use them regularly if you are a serious diy electrician or your goal is to become a serious diy electrician. If you intend to do a lot of electrical work I strongly recommend that you purchase a current copy of the NEC (National Electrical Code), NFPA (National Fire Protection Association) Publication 70. This, depending on the format purchased will run anywhere form $80 to $125 but it’s a mandatory addition to your reference book collection. It’s the electrician bible and all work must meet it standards in order to be safe and able to pass inspection. When it comes to working with electricity it is important to remember that just because something works doesn’t mean that it’s safe.
There are several types of receptacle circuits found in residences
1.) General purpose receptacle circuits. These are circuits where all the duplex receptacles are wired in parallel and protected by one circuit breaker or fuse.
2.) Switched receptacle circuits. These are similar to the general purpose receptacle circuit with the exception being that one half of one or more of the duplex receptacles are controlled by a wall switch. Switched receptacle circuits are usually found in rooms where all the lighting comes from floor or table lamps. As a rule both halves of these circuits are protected by the same circuit breaker or fuse. If you replace a receptacle on a switched circuit make sure to cut the brass tie between the two brass screw on the receptacle you are installing. If you don’t cut this tie the switch will no longer control the receptacle because they will be energized from the non-switched side of the circuit
3.) Split-wired receptacle circuits. These are circuits where each device is fed by two hot wires and a common neutral and protected by a double pole breaker or two single pole breakers tied together with a handle tie. This type of circuit is easy to recognize because each receptacle will have a red, black, and white conductor attached to it. The red and black insulated conductors are the hot conductors and, if you place your voltmeter probes on them you will read a nominal 220 volts and if you place the voltmeter probes between either the red and the white or the black and the white conductors you will read a nominal 110 Volts. Another indication of a split wired receptacle circuit is that the brass tie between the two brass screws on the receptacle have been cut. If you don’t cut this tie you will create a phase to phase short and the cb (circuit breaker) will trip or one of the fuses will blow as soon as you re-energize the circuit.
4.) Dedicated receptacle circuits. These are receptacle circuits with only one receptacle on it supplying a single appliance like a window A/C unit, dishwasher, garbage disposal unit, etc.
5.) Kitchen counter top circuits. The code requires that all kitchen counter tops be supplied by a minimum of two 20A GFCI (Ground Fault Current Interruption) circuits. The GFCI protection may be supplied by a GFCI cb which can be recognized by their “Test” and “Reset” buttons in addition to their toggle handle. GFCI may also be supplied by using a GFCI receptacle as the first receptacle on the circuit. These are feed through devices with the GFCI receptacle providing GFCI protection to all the standard receptacles down stream from it. GFCI receptacle are also easily recognized by their “Test” and “Reset” buttons. Some GFCI receptacles also have a built-in LED (light emitting diode) that will indicate when the GFCI has tripped open. The thing to remember if you have a GFCI circuit protected by a GFCI cb and it’s dead the cb itself may not appear to be tripped open because that only occurs when there is a short circuit or when the circuit was overloaded. The GFCI part of the breaker is designed to protect people against leakages current in excess 6 ma (milliamperes), 0.006 A (Amperes) which happens when a person makes bodily contact with a neutral conductor. If a GFCI circuit is dead and the GFCI cb isn’t tripped, try resetting the reset button. More on GFCI troubleshooting later.
Dead general purpose receptacles circuits, switched receptacle circuits, dedicated receptacle circuits and split-wired receptacle circuits can be caused by many different problems.
A dead receptacle circuit can be caused by a tripped cb or blown fuse. If a tripped cb trips out again as soon as you reset it or a fuse blow again as soon as you replace it, you have a short circuit on your hands. The short could be caused by a hot conductor coming in contact with either the grounded circuit conductor, the “neural conductor”, or by it coming in contact with the grounding conductor, the “green” or bare conductor, The short may also be caused by some appliance or other deice that you have plugged into the circuit so unplug everything and try resetting the cb again. If it doesn’t trip again the problem lies with something you had plugged in. Troubleshooting those devices is grist for many factoids but for the time being, using your digital Multimeter set on a low ohms scale. take a reading between the hot side of the plug-the narrow blade- and both the “neutral” blade and the round ground pin. If you get a zero resistance reading on either of those tests the device is shorted and shouldn’t be plugged back in until you locate the cause of the short.
A dead receptacle circuit can be caused by an open circuit. The hot conduct or may have come loose at the receptacle. If you have more than one dead receptacle on the same circuit, check for the loose hot wire at the first dead receptacle and at the last live receptacle on that circuit.
A dead receptacle circuit may also be caused by a “dropped neutral”. A dropped neutral occurs when the continuity of the neutral conductor is broken somewhere between the first dead receptacle and the neutral bar in the panel or between the first dead receptacle in the string and the live receptacle feeding them. Dropped neutrals present one of the greatest safety hazards to the diy electrician because most people assume that if the receptacle is dead that there isn’t any voltage present at the receptacle but with a dropped neutral the hot wire is still very hot and can kill you. If the system that you are working on is well grounded you can use your voltmeter to take a reading between the hot conductor and ground to verify the presence of live voltage but if there’s no ground the circuit will falsely to be safe. Use you non-contact voltage detector to verify if the circuit is safe to work on. This instrument doesn’t require a ground to detect live voltage. While I’m on the subject of open circuits and dropped neutral you may have a bad splice in a junction box and not in one of the device boxes. Wire nuts have been known to come loose and dipped solder joints have been known to break with age. Dipped soldered and taped joints haven’t been used for many years but if you have an older home with the original wiring still in use there’s a good possibility that your home has dipped soldered and taped splices. I was once called to an older home to troubleshoot intermittent receptacles in the living room. Every time the refrigerator kicked on the receptacle went dead. The refrigerator kept right on purring away so that eliminated an overloaded circuit. None of the cbs were tripped, so I suspected an intermittent circuit connection. Some one had replaced the original Edison Based fuse box with a modern circuit breaker panel but the cabling was still the older BXL (Armored Cable) so I suspected dipped soldered and taped connections. Sure enough I found a splice box in the basement right under where the refrigerator stood and there was a neutral that had broken loose.
If the dead receptacle are on a switched circuit check for a bad switch or for a bad connection at the switch.
If you have any faceplates that are warm to the touch the warning lights should start flashing in your brain because you have a fire looking for a place to happen. A warm faceplate tells us that there’s arcing going on at that receptacle or switch. The arcing could be caused by a loose connection where the conductors connect to the device or by worn contacts inside the device. Investigate at once and repair or replace as the situation calls for.
Resources
Home Depot http://www.homedepot.com
Lowes http://www.lowes.com
