Looking Good Gfci On Ungrounded Circuit

A gfci can shut off the current if a short occurs between a circuit wire and ground without a ground wire necessarily being present.

Gfci on ungrounded circuit. This is a legal method of gfci protection with a 2 wire circuit. These outlets are considered safe to install on an un grounded circuit and replaces those inconvenient 2 prong outlets. Grounding type receptacles supplied through the ground fault circuit interrupter shall be marked gfci protected and no equipment ground an equipment grounding conductor shall not be connected between the grounding type receptacles.

406 4 d 2 non grounding type receptacles. The diagram below shows a typical non grounding 2 prong receptacle replaced with a gfci. Gfci s can be used in place of ungrounded receptacles and used for those ungrounded receptacles down line on the same branch circuit.

It s not bad to use a gfci on an ungrounded circuit the ground fault interrupt function does not rely at all on the 3rd wire the ground wire. Gfci s receptacles on ungrounded receptacles afford no protection. The national electric code now requires gfci receptacles near sinks in kitchens bathrooms basements and outdoor circuits.

Replacing ungrounded 2 prong outlets with a gfci outlet an old style non grounded outlet may be replaced with a gfci outlet and the ground fault protection circuitry and capabilities will still work. Section 406 3 d 3 of the 2008 national electric code permits a non grounding type receptacle to be replaced with a grounding type receptacle without a grounding connection. If you want to run a ground wire back to the panel that feeds this circuit or if there is a grounded circuit in the area that is fed from the same panel recent code changes allow a new separate ground wire to be installed.

A gfci works even on an ungrounded circuit to shut off power when it detects a current differential between hot and neutral above some threshhold typically 10 ma. You ve no doubt seen these before at bathrooms or kitchens and you can read more about these on a previous post here. All receptacles must be labeled gfci protected and ungrounded equipment in such cases.

However the purpose of gfci is to save your life it will cut off power in cases where you become part of the circuit preventing you from being electrocuted. When replacing a 2 wire outlet with a gfci outlet the outlet must be labeled indicating that there is no ground available.