After installing GFCI on a branch circuit I discovered that the transient voltage surge suppressor (TVSS) I used for the television trips the GFCI. At first I thought the TV, VCR, DVD, or clock had developed a ground fault, but after unplugging all the loads, the GFCI still tripped until I removed the TVSS.
The surge suppressor is a 120V/60Hz 10A DataShield Model 85. It is the type that has an integral relay, so the relay disconnects the unit from the line until reset. Operating the TVSS's reset button momentarily energizes the relay, then the GFCI trips deenergizing the relay again.
When unplugged, continuity measurements show an open circuit for all combinations measured at the plug. Because of the relay, continuity measurements from outside the unit to the electronics is impossible because the deenergized relay keeps the electronics open circuited.
I'm guessing the unit is the type that shunts surges from HOT and/or NEUT to GND, rather than shunting surge from HOT to NEUT.
When on an branch circuit without GFCI, the relay can be energized and the unit does carry loads normally, although I have no way of knowing if it offers surge suppression anymore.
It appears that the TVSS itself has a ground fault. I tried to open it up, but would have to almost destroy the unit to access the electronics inside. The only thing exposed once the bottom cover is removed are a 10A fuse and the bottom of a tightly secured circuit board.
I'll be throwing this old, $75 unit away, but I'm curious about what is causing the ground fault. My guess is the neutral maybe grounded inside the unit.
Thanks for reading all this.
What do you think could be the problem???
