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Posted by Tom Horne, Electrician on December 1, 2006, 4:29 pm
Chris Friesen wrote:
> Chris Friesen wrote:
>
>> According to the diagrams here
>>
>> http://www.codecheck.com/gfci_principal.htm
>>
>> the test button diverts some current from hot to ground to cause the
>> hot/neutral conductors to not carry the same amount of current.
>> Without a ground, how would the test button work? Where does the
>> diverted current go?
>
> Doh...should learn to research first. Found an alternate design where
> the test button diverts some current around the sensing toroid back to
> neutral such that the toroid sees unbalanced current even though it is
> actually balanced for the receptacle as a whole.
>
> Works just fine with no real ground.
>
> Chris
Chris
That scheme only applies to the built in test circuit in the GFCI
itself. A plug in tester does indeed need a ground in order to work but
the ground only has to be good enough to carry six milliamperes. That
would not make it a satisfactory low impedance pathway back to the
source via the main bonding jumper.
--
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison
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