Electrical Projects One side of the 115V ac power line is grounded (by the power company) and the other side of the line is "hot" with respect to ground. To use the ground checker, the appliance is plugged into Jl which will accept either a two-prong or three-prong plug. With P plugged into an ac outlet, either terminal X or Y of Jl will be grounded through the power line, depending upon which way P is plugged into the outlet.

When checking an appliance or tool that has a three-prong safety plug, flip switch S from one position to the other. If the third wire of the power cable is connected internally to the metal case of the device, lamp I should light when S is in one position, but not in the other. When checking a device that has a two-prong power plug, connect J2 to the metal case of the device (or other exposed metal part) through a clip lead. The lamp should not light when set to either position. If the lamp does light, there is an internal ground in the device.





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November 20, 2008