Heat element & shore gfci

dougrainer wrote:

Bobbo wrote:
Yep. That is THE classic cause of a ground fault. Turning on the electric element in the water heater without water in the tank almost instantly ruins the heating element. The heating element then makes contact with ground. That NEUTRAL/GROUND contact trips the GFCI every time. Your solution is to replace the heating element in the water heater. The breaker being on or off doesn't matter. The short is between NEUTRAL and GROUND, and neither one is disconnected by a breaker.

Sorry, When a Water Heater Element "Blows", there is NO CONTAC to a ground source. The Blown part looks like a small weld slag on the element. What DOES cause a GFCI to trip is the IMBALANCE of current between the Neutral and HOT. So, When the Current tries to flow thru the Heat element, the blown element causes an imbalance, of current and the GFCI sees this as a Short to Ground. I have found very few 120 Water Heaters connected to a GFCI, but it makes sense to have it connected to a GFCI. Doug

You misunderstand how a GFCI works and electricity for that matter. Current does not "try to flow" in an open circuit. The breaker was off so there is no try.

Also, a GFCI not only detects a current imbalance between hot and neutral, it also attempts to inject a small current into the neutral wire. If there is a loop formed due to a short between neutral and ground downstream (completing the loop where the neutral and ground are shorted upstream in the main panel), current will flow around that loop and get detected on the neutral but not on the hot. This is how a GFCI can trip with the hot wire completely open at the breaker. Clearly in this case there was a neutral to ground short at the element itself.