ground fault after installing metal conduit?

Hey guys, I just installed EMT conduit on my fire alarm system and now my SK 5208 says ground fault. I’m using a grounded plug. Anybody have any idea on how to solve the problem?

Ground faults occur when there is a dead short to ground in the system’s wiring - it’s unrelated to the 120VAC input. Most likely, one of your wires is nicked and is touching the conduit.



The best way to troubleshoot ground faults is to disconnect all circuits one by one until it disappears. Once you’ve narrowed down the run of wire that’s causing the ground fault, try re-fishing it through the conduit and it might just go away. You may need to replace that wire if it doesn’t.



Also, I’ve occasionally gotten ground faults when there’s a very deep notification appliance pushing the wire up against its backbox. Try loosening each device on the system and see if the trouble clears.


Thanks man! Turns out it was a resistor touching the back box on the strobe NAC circuit.


Now I have a question.



How would you solve that problem with an addressable system?

Same method. Most addressable panels still can’t tell exactly where the ground fault is, so you have to find it by trial and error. On a large loop with many devices, it helps to go down the line and disconnect devices until the trouble goes away.



Here’s a video showing a way to troubleshoot ground faults on Silent Knight panels:

http://www.youtube.com/watch?v=-vPtefLdsrM

Oh so it works like any other panel.

I have a similar problem with an Edwards SPO, expect the fault trouble still appears even after I covered the terminals in electrical tape.

Could be the switch grounding through the switch housing to the backbox. Make a plastic or cardboard gasket to fit the back of the pull and try that.

No, do not try that.



The switch should not be close enough to touch anything, if it is you need a different box.

I was thinking about covering the edge of the electrical box in electrical tape, and then testing it. What’s also weird, is that it does not activate the alarm whenever it is mounted in the electrical box. It works, and doesn’t cause a ground fault whenever it dangles by the wires. It is strange.

In that case it would probably be the box.

Let me clarify…whenever I remove the pull station, the ground fault trouble disappears.



I take that to mean that if you have the pull connected but not installed in the box, it’s fine, but when it’s in the box, it causes a ground fault?

It would be the box in that case, otherwise it’s the pull itself.

The pull station also does not work when it is installed in the box. What do you mean by “it’s the box”?

There may be a nicked wire. Do you have another pull station to try? How about a few photos of the box/setup in question.

I’ve used other pull stations, with no problems. It’s just that one. I don’t think it is a nicked wire. I disconnected it multiple times, and capped the wires, no problem. I’ve had two other pull stations in that same box, no problem. I will eventually cover the edge of the electrical box that touches the pull station with electrical tape. There might be something wrong with the pull station.

If you narrow it down to the pull station, throw it away and just replace it. Don’t use a hacked solution to fix the problem.

The pull station wouldn’t work anyway.


Sounds like the wire is touching the metal on the pull station, or the switch is shorting it out. But some wire somewhere on the pull is touching the metal box. Or try a new pull and see if it clears


Try taking the switch out of the pull while it is wired up and touch any of the metal parts on the switch to the backbox. if it shows up as a ground fault, the switch is shorting it out.