Testing a Ground Fault Circuit Interrupter ( GFCI ) Receptacle
May 2, 2006
Q: I bought a plug-in type GFCI tester at Home Depot or Lowe’s, I’m not sure. On the back of the package it says that the tester is listed and designed for testing the operation of GFCI receptacles. Sometimes when I plug the tester into a GFCI receptacle, it does not trip. However, when I press the test button on the receptacle, it does trip. Should I be concerned because the tester does not trip the GFCI?
A: Most, if not all, GFCI receptacle manufacturers recommend using the test button on the device to ensure proper operation. If a small load, like a table lamp or floor lamp, is plugged into the GFCI receptacle and turned on, then the test button on the GFCI is pressed, and the lamp goes out, the GFCI receptacle is working, and is properly wired. If the unit trips, but the lamp remains energized, the GFCI receptacle is miswired. To correct this situation, the wires connected to the receptacle’s “line and load” terminals must be reversed.
A plug-in type GFCI tester causes current to flow from the ungrounded conductor to the equipment grounding conductor when it is plugged into the receptacle. This method allows an unbalanced current flow through the GFCI. If the tester does not cause the GFCI to trip, the tester could be defective, the receptacle could be miswired, or there could be an open or no equipment grounding conductor in the circuit.
An equipment grounding conductor is not required for GFCI receptacles that are being installed as replacements for existing receptacles during remodeling of a dwelling unit. Section 210-7(d)(2) requires GFCI receptacles as replacements where other Sections of the NEC specify locations that must have this protection. And Section 210-7(d)(3)(b) requires that these receptacles be marked “No Equipment Ground.”
If the plug-in type GFCI tester does not trip the GFCI and you know the tester is functioning properly, the receptacle should be removed from the outlet box to check the presence/absence of an equipment grounding conductor. If the conductor is present, it is not continuous to the outlet. If it is not present, the receptacle should be marked “No Equipment Ground.”
There is a revision to the UL 943 GFCI Standard for Safety which is scheduled to take effect on July 28, 2006. The revised standard incorporates the following changes:
- End of Life Provision: When a GFCI receptacle is incapable of passing its internal test function (it can no longer provide ground fault protection), it will comply with either (a) or (b):
- Render itself incapable of delivering power
- Indicate by visual and/or audible means that the device must be replaced
- Reverse Line-Load Miswire: A GFCI will deny power to the receptacle face if it’s miswired.
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