"George Patterson" wrote in message news
81If.23857$Eq.13398@trnddc02...
wrote:
If one of your pieces of equipment were leaking current into the water, the GFCI would trip.
You are correct, but it is important to know, it does not work like "all or nothing".
All GFCI are rated with a leak current detection threshold - they trip if the leak
current is bigger than a threshold and continue to work normally if the leaking
current is below the threshold. For many GFCI this threshold is set to the level
of 20-30mA. This is quite a strong current causing pain and musscle retraction
when applied to human skin. The purpose is not to kill a user only... but you
might still get zapped quite seriously and painful before the GFCI will trip.
And, what is more important in our aquarium applications: small currents
(below the threshold) continue to leak without being detected by GFCI...
So you can clearly have, lets say 5-10mA current leaking from your powerhead
failing insulation and your GFCI will do nothing to stop it. Will your fish feel it ?
We would need to ask them ;-)