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Grounded vs GFCI Question


Terence McCann
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For discussion: An older home with K&T.

A refrigerator has motor windings that are breaking down and leaking current to the case. You touch the case and then touch the sink and start getting zapped. On a grounded outlet, the ground will give the electrons a path back to ground and thus prevent this shock hazard from happening, no? Will a GFCI protect you in this example (I know we don't recommend GFCI on refers)?

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Originally posted by Terence McCann

For discussion: An older home with K&T.

A refrigerator has motor windings that are breaking down and leaking current to the case. You touch the case and then touch the sink and start getting zapped. On a grounded outlet, the ground will give the electrons a path back to ground and thus prevent this shock hazard from happening, no?

It'll provide a low-resistance path back to the origin of the circuit. Current will still flow through all available paths back to the source in proportion to the resistance of the path. If the receptacle is well-grounded, most of the current from the case will travel back that way. If it's more than 15 or 20 amps worth, it might even trip the breaker.

Will a GFCI protect you in this example (I know we don't recommend GFCI on refers)?

Sure.

I've probably told this story before:

When I was a kid, some friends of mine had a fridge that did this but you didn't need to touch the sink. Every time you'd touch the fridge, you'd get bit. Their solution was to put a thick throw rug in front of it and a towel on the fridge handle.

They had a peculiar dog who got off on being shocked. He'd stretch out on the floor and touch one paw to the fridge case then his eyes would roll back in his head and he'd make little grunting sounds.

Hey, whatever rocks your boat.

- Jim Katen, Oregon

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  • 3 weeks later...

lol....I just don't know what to say...lol.....I am however very glad jim made this statement: "It'll provide a low-resistance path back to the origin of the circuit. Current will still flow through all available paths back to the source in proportion to the resistance of the path. If the receptacle is well-grounded, most of the current from the case will travel back that way."

Wise man that Jim.....you are all lucky you have a MOD that ACTUALLY understands how electricity works....:)

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Terry, It sounds like the question is whether it would be OK to install an ungrounded GFCI for protection. I would think it would protect against shocks but should trip every time you touch the fridge (would probably trip every time you plugged in the fridge), so doesn't seem to me to be a practical solution. Besides, it would just piss off the dog.

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Great story, I'm going to have to try it, but I guess I have to UN-ground the fridge first.

If I do it while I'm "kissing" my girlfriend will she feel the effects too? She used to tell me she tingled whenever we "kissed". I could use the help.

Do I thank Jim for sharing it or the dog for coming up with the idea?

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How it works??? I always thought we sort of knew how it *behaved*, and we sort of know how to control it, but I didn't think anyone, yet, knows how electricity *works*. But could be the third or fourth time today I'm wrong about something (my daughters are home today).

Originally posted by PAbernathy

lol....I just don't know what to say...lol.....I am however very glad jim made this statement: "It'll provide a low-resistance path back to the origin of the circuit. Current will still flow through all available paths back to the source in proportion to the resistance of the path. If the receptacle is well-grounded, most of the current from the case will travel back that way."

Wise man that Jim.....you are all lucky you have a MOD that ACTUALLY understands how electricity works....:)

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