Earth Trouble with Simplex 4006

I’m getting an Earth Trouble alarm on my Simplex 4006. I have bypassed all of the pull stations and I’m still getting the alarm.

Does anyone have any idea where I should check next?

Moved to correct forum.

Not quite sure of you technical level here, so I’ll explain a few things then get to your problem…

A “Earth Fault” (or Ground Fault on other control panels) basically means there is a bare wire somewhere in the system touching the electrical ground of the building. This can be caused by poor installation practices - where the installer or service tech got a little crazy stripping the wires and left some bare copper exposed, and in the process of shoving the wires into a electrical back box or mounting a device, that wire over time moved just enough to contact the metal of the electrical box itself. This is probably the majority of the causes of ground faults. You can get instances where water gets into a box from a roof or plumbing leak, some ill-meaning contractor did some work in the building and damaged some fire alarm wiring or devices, or even rodents chewing on wire causing all kinds of problems. There can also be an issue with the main fire alarm panel itself - this would be an “internal ground fault” where the something on the board itself is touching ground (usually caused by a voltage surge or lightening strike). Internal ground faults are not fixable and your only solution is to replace the damaged board.

Now, for your problem. Simply bypassing the pull stations isn’t going to clear the ground fault. The system just ignores any alarms from those zones but continues to supervise the zones and will indicate when there is a problem. And your problem may not even be on a pull station zone. Could be a ground fault on the notification (NAC) outputs. One thing you can try is disconnecting one set of wires at a time and see if the ground fault clears. Only take off one pair from each zone and NAC at a time - and if the ground fault clears, that will give you an indication which circuit is effected. If nothing clears, then it may be an internal fault or ground faults on multiple circuits.

In all honestly, ground faults are not easy or fun to trace out and even for experienced technicians can become frustrating. Your best bet may be to call an alarm tech and have him determine the problem exactly. Just too many factors that may be causing your issue then you can find help with here.

This might be a dumb question. Is the panel can properly grounded? Is the electric outlet grounded? There might be an issue with that.

Oftentimes, ground faults are not caused by a failure to use a grounded 120VAC power input, but by a loose wire touching a piece of metal, either a backbox or length of conduit. Silent Knight used to have a video up on their YouTube channel demonstrating how to troubleshoot a ground fault on their IntelliKnight line of addressable panels, however it appears to have been taken down.