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iLearn

join:2013-01-16
canada
reply to garys_2k

Re: First post - recently joined - GFCI without a ground wire

Thank you. I understand it now.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
Here is a diagram from wikipedia RCD entry and really simplified description to help you visualize what is inside a typical GFCI outlet.

Both hot and neutral (L/N) conductors pass through the core of a single current transformer (3). Ideally the currents flowing through L/N are identical and in opposite direction, so effectively zero current flows through the coil (2).

But when there is some leakage current from either L or N (to some grounded human or grounded object) the electromagnet (1) disconnects both L/N conductors from the outlet.

The ground conductor (when available) is connected straight through to the ground of the outlet. So when a GFCI outlet has tripped, ground prong is still connected to ground, but the L/N prongs are both floating.

P.S. The test switch (4) bypasses about 5mA from L to N.

iLearn

join:2013-01-16
canada
ah great, now I am confused again (j/k)

Bob4
Account deleted

join:2012-07-22
New Jersey
Reviews:
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Shorter answer: With a properly-functioning appliance, the current on the hot and neutral prongs is the same. If there's a problem and the current is instead traveling through, for example, your body, the GFCI outlet will trip and cut-off the current. A ground wire is not necessary for this protection.