Quote:
Originally Posted by Bill R
Someone throw me a bone here. How does a GFCI work if there is no ground connection? The plugs like this I have taken appart only have a thermal switch that will trip like a circuit breaker. Some had two contacts to break line and neutral. Since a GFCI senses current in the ground wire you would have to have a 3 conductor plug. I thought. You would be surprised how many people come in the store and spend a lot of money on surge protectors then use a cheap adaptor to plug it into a 2 prong outlet. I agree if you need GFCI protection I would install the outlet, or a GFCI circuit breaker . Anyone comfortable working on a vintage tv should have no problem.
Bill R
|
The hot and neutral wires wrap through a toroid transformer core and constitute the primary of the transformer. Then they go to a PAIR of relay contacts hooked up to a spring loaded disconnect mechanism. The other side of the relay is the outlet plug. Meanwhile back at the transformer, the secondary has a gazillion windings, making it very sensitive. When the current going OUT the hot wire is EXACTLY balanced by the current going BACK through the neutral, there is NO magnetism induced in the transformer. When an inbalance occurs, then that sensitive secondary with the gazillion turns gets energized. Then an integrated circuit (usually) powered by the line (before the relay) senses the voltage and energizes a coil that trips the spring loaded disconnect mechanism on the relay , sort of like a mousetrap.
The hot and neutral open up immediately. No ground is needed.
IF you were insulated from ground and got across the hot and neutral, you could get zapped without a disconnect.
The GFCI BOX breaker has an extra white wire which is the dedicated neutral that HAS to be run to every outlet serviced by that breaker. That might account for any "ground" confusion.
The internals of the GFCI outlet haven't changed much in the last 20 years or more, I recently replaced one and opened up the old OLD GFCI that was in the house when I got it 15 years ago, and the design was the same. The internal inspection sticker was early 80's.