T&T: loose neutral

[Peter Bennett]

Friday, May 4, 2007, 3:58:31 PM, Pierre wrote:

>> A GFCI for a 240 volt load would have to compare the currents in the two
>> hot wires, where a 120 V GFCI compares currents in hot and neutral.

P> So, Peter, how do you protect yourself from 240V?

A 240V GFCI as I described would protect you from faults in a 240 volt
load.

Note that the name of the things - "Ground Fault Circuit Interrupter"
- is a bit misleading.  A GFCI (even a 120V version) does not look at
the current in the ground wire.  It looks at the currents in the
current-carrying conductors, and, if they are sufficiently different
(by 5mA for the GFCI 120V outlets), considers that there is a fault
somewhere, and turns off the power.  The assumption is that the
"missing" current made it to ground somehow, not necessarily through
the green wire that is passing by the GFCI.

-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Lien Hwa 28 (AKA Polaris 30) "Sea Spray"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca