Diagnosing Electrical Problems

Typically, you discover you have an electrical problem when you turn on a lamp or appliance and it won't work. When that happens, the source of the problem may be the device itself, faulty wiring connections, an overloaded or a short circuit.

Overloaded circuit
A circuit becomes overloaded when there are more lamps and appliances on it than it can safely handle. When all the lamps and appliances are turned on, the wiring overheats and the fuse blows or the circuit breaker trips.

Short circuit
A short circuit occurs when a bare hot wire touches a bare neutral wire or a bare grounded wire (or some other ground). The flow of extra current blows a fuse or trips a circuit breaker.

Helpful Diagnostic Hint
Plug fuses provide a clue to what made them blow
An overload melts the bridge.
A short circuit blackens the glass.
Light Fixture Won't Work

Check for:

* Burnt out bulb or fluorescent tube
* Defective fluorescent starter
* Faulty switch
* Loose wiring
* Faulty socket

Remedies:

* Replace bulb or tube
* Replace fluorescent starter
* Replace switch
* Tighten connections at switch or fixture
* WHAT ABOUT SOCKET?

Appliance Won't Work

Check for:

* Overloaded circuit
* Damaged plug
* Damaged cord
* Loose wiring
* Defect in appliance or lamp

Remedies:

* Test for overload -- shift appliance or lamp to another circuit
* Replace plug
* Replace cord
* Tighten connections at switch or receptacle
* Test in another circuit -- repair if faulty

Appliance or Lamp Won't Work in One Circuit -- Works in Others

Check for:

* Overloaded circuit
* Loose connection at receptacle
* Short circuit

Remedies

* Test for overload; shift appliance or lamp to another circuit
* Tighten connections at receptacle
* Test for short circuit; make necessary repair

Appliance or Lamp Won't Work in One Receptacle of Circuit

Check for:

* Loose wiring
* Faulty receptacle
* Short circuit

Remedies:

* Tighten connections at receptacle
* Replace receptacle
* Test for short circuit; make necessary repair

Appliance or Lamp Won't Work in Switch-Controlled Receptacle

Check for:

* Loose wiring
* Faulty switch
* Faulty receptacle

Remedies:

* Tighten connections at switch or receptacle
* Replace switch
* Replace receptacle

Some Lights on Circuit Won't Work

Check for:

* Loose wiring
* Faulty switch

Remedies:

* Tighten connections at switch or fixture
* Replace switch

No Lights on Circuit Work

Check for:

* Overloaded circuit
* Short circuit
* Loose wiring
* Faulty switch

Remedies:

* Test for overload; make necessary adjustment
* Test for short circuit; make necessary repair
* Tighten connections at switch
* Replace switch

Tracing a Short Circuit or Overload

A blown fuse or tripped circuit breaker is a signal that you may have either a short circuit or an overload in the electrical system.

* Look for black smudge marks on switch or receptacle cover plates, or for frayed or damaged cords or damaged plugs on lamps and appliances connected to the dead circuit.
* Replace a damaged cord or plug.
* Then replace the fuse or reset the breaker.
* If the circuit goes dead after an appliance has been in use for a short time, you probably have an overloaded circuit.
* Move some of the lamps and appliances to another circuit and replace the fuse or reset the circuit breaker for the first circuit.

Don't find any of the above signs of trouble? Trace your way through the circuit using the steps below.

* Turn off all wall switches and unplug every lamp and appliance on the dead circuit.
* Install a new fuse or reset the tripped breaker.
* If the fuse blows or the breaker trips right away, the problem may be a short circuit in a switch or receptacle.
* With the circuit dead, remove each cover plate and inspect the device and its wiring.
* Look for charred wire insulation, wire shorted against the metal box or a device that's defective.
* Replace a defective device.
* Call in an electrician to replace faulty wiring.
* If the new fuse doesn't blow or the breaker doesn't trip right away, turn on each wall switch, one by one, checking each time to see if the fuse has blown or the circuit breaker has tripped.
* If turning on a wall switch causes a fuse to blow or the breaker to trip, there's a short circuit in a light fixture or receptacle, controlled by that switch, or there's a short circuit in the switch wiring.
* With the circuit dead, inspect the fixture, receptacle, and switch for charred wire insulation or faulty connections.
* Replace a faulty switch or fixture.
* Call in an electrician to replace wiring.

Problem still not solved? You probably have faulty wiring. Call an electrician to correct the problem.

If turning on a wall switch doesn't blow a fuse or trip the breaker, the trouble is in the lamps or appliances.

* Test them by plugging them in one by one.
* If the circuit doesn't go dead, the circuit was overloaded.
* Move some of the lamps or appliances to another circuit.
* If the circuit does go dead just after you've plugged in a lamp or appliance, then you've found the offender.
* If the circuit goes dead as soon as you plug in a lamp or appliance, the plug or cord is probably at fault and should be replaced.
* If the circuit goes dead when you turn on the lamp or appliance, the appliance or lamp or its switch is probably defective and should be replaced or repaired.