I do some hydroponic growing for a hobby. I use some small submersible
pumps and air pumps. Because the nutrient solution is essentially a salt
solution, I use GFCI for personal protection against shock.
A timer is used to turn the pumps on and off. I have been getting
occasional trips upon turning the pumps off. This makes me think that
the problem comes from inductive kicks when the switch is opened. I have
put about 0.2 microfarads between the hot and neutral lines. That seems
to solve the problem for now.
I am not sure just how the problem arises. My guess is that the
inductive kick must be breaking down insulation so that I get some
ground current during the inductive spike. That cannot be good for the
long term integrity of the insulation.
To get a better handle on the problem, I was thinking of removing the
ground connection to the pumps to see if I still get trips upon opening
of the switch. Without a ground connection, it would be impossible to
get ground fault current unless there is an external ground connection,
such as me being grounded and sticking my hand into the reservoir. The
GFCI would still protect me in such a situation.
So my question is: What other mechanism can be at work to cause trips
other than breakdown to ground?
11 years ago