"Understanding Your Home" by Building Inspector Mark Visser
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Plug-in circuit testers
The yellow circuit tester is for regular receptacles while the red one also can be used for testing GFCI receptacles.
These inexpensive testers are great tools and there should be one in every toolbox or workshop.


3-to-2 Adapter
Use of these "cheater plugs" is NOT recommended and even illegal to use in Canada.


Ungrounded Receptacles...
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Ungrounded receptacles. Plug-in circuit tester. GFCI receptacle testers.

Electrical service equipment has always been grounded. After 1960 it became standard practice to ground all house branch circuits as well. Many older homes may still have ungrounded receptacles even after the service has been upgraded because branch circuit wiring to bedrooms and upper floors has not been replaced. Power is still supplied by the older two-wire (no ground) cable.
Don't be fooled by the presence of 3-hole receptacles in an older home. The receptacle may be new but the wiring is not. The best way to find out if a receptacle is grounded is to use a circuit tester. Just plug the circuit tester into a standard 120 volt receptacle and view the lighted 3 lamp status display for verification of correct wiring. You will be able to check for open ground, open neutral, open hot, hot-ground reversal and hot-neutral reversal fault conditions. The yellow circuit tester in the picture is used for regular receptacles while the red one also can be used for testing ground fault circuit interrupter (GFCI) receptacles.

Side-by-side lights indicating correct wiring
Not all testers are configured the same. Some show side-by-side lights for OK wiring, as illustrated, while others are programmed different.
There are several ways to make an ungrounded recepticle safe.

1- Rewire the receptacle.
2- Install a GFCI receptacle but don't connect anything to the ground screw. However, if the computer's surge protector is plugged into the GFI a close strike can still damage the computer.
3-Connecting a groundwire to the nearest cold water pipe is NOT recommended.
Using a 3-to-2 "cheater plug" adapter with the tap connected to the plate screw is NOT recommended because if the metal boxes are not bonded with a ground wire grounding the adapter screw is not beneficial. These adapter plugs are not approved for use in Canada.
WARNING. Before starting any work on the electrical system make sure that the power has been turned off at the distribution panel.

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