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Electrical Basics - Safety, Tools, Multimeter, Fuses

Safety First: Before starting any electrical project, turn off the main power source to your home by either tripping (shutting to the off position) the circuit breaker or removing the fuse at the main service panel. Next use a voltage detector (see description below) to make sure there is no power to the site you are working on.
Tools: You will need the following tools to do any home repair job:
  1.  Voltage detector: This is a small pen like instrument that you can hold to any outlet or light and it will light up if the electricity is still connected to the source. You can find this at any hardware store.
  2. Diagonal wire cutters or wire strippers: All electrical wire is covered with a protective vinyl coating (insulation). You will need these tools to strip the vinyl from the wire so you can connect the bare wire to the terminal.
  3. Needle nose pliers: These will help you to get into tight spotsand bend wire.
  4. Flathead screwdriver.
  5. Electrical tape: This is used to cover any open wires.
  6. Electrical caps: (also called wirenuts) Small plastic caps used to connect wires together
  7. Multimeter: (also called multitester or volt-ohm meter) This instrument measures the amount of voltage from any appliance or outlet. You do not need this if you are installing anything; rather this will tell you how much voltage you are getting to a light that is dim, a toaster that isn’t working, etc.
    Doorbells, security alarms, and thermostats all run on voltage that is too low for voltage detectors to work. Only a multimeter will work on such low voltage.
Using A Multimeter:
  1. On small appliances, to check if a circuit is complete, unplug the appliance and turn it on. Set the meter to its lowest range (usually RX1) Touch the probes to the appliance plug’s prongs. Twenty to 100 ohms is adequate. Zero may mean there is a short in the circuit. A high reading indicates an open circuit.
  2. To check a heating element on your kitchen stove: Remove the element from the stove. Set the multimeter at its lowest range. Touch the probe to both terminals of the element. Twenty to 100 ohms is good. Anything under that range means you need to replace the element.
Electrical Basics
Your home should have a power box where the main source of electrical power enters the home. If you have a newer home, this box will be made up of circuit breakers which just need to be flipped to the off position before doing any repairs. If your home is older, it may have a fuse box as the power box. The fuses must be removed to disconnect the power. All fuses and circuit breakers should be labeled. It is a good idea to have a rubber mat or piece of wood to stand on under your power box to prevent shock.

All electrical wires are covered by a coating of insulation to prevent electrical shocks. Each outlet or light switch has 3 wires going into the power source. These wires are color coded. Black is always the hot wire which maintains the electrical source. White is always a neutral wire and completes the circuit. Green is the ground wire, which prevents shocks.

If you have an older home, you may not have a green grounding wire. Bare copper may also have been used as a grounding wire. Some homes may only have one black and one white wire. In this situation, the WHITE wire may be the hot wire; if the home was properly wired, it would have been wrapped in black electrical tape to indicate that it is hot. If you do have an older wiring system, it is best to call a professional electrician to check it out.

Changing Electrical Fuses
Older homes with fuse boxes frequently “blow” a fuse because of inadequate power. To change a fuse, pull out the faulty fuse. To determine the cause of the failure, inspect the fuse. If the window is cloudy or discolored, the cause was probably just a short circuit. If the window is clear and the metal ribbon inside the fuse is separated or parted, the cause was a borderline circuit overload.

Aluminum Wiring Caution
Homes built in the 1960’s and early 1970’s were sometimes wired with aluminum wiring. This can be a fire hazard if it was improperly installed or upgraded. Examine your cables at your power box. If the cables entering the service panel are marked AL, they are aluminum. Call an electrician to inspect this system.


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