Called out today to an eight zone Sigma CP K fire panel that has a intermittent Earth Fault that can last for a few hours or a few seconds. No zone or sounder fault led's operate just the general fault led. All earth connections have been disconnected but still the fault, any ideas? Could the fault be caused by the mains earth?

All earths?

All earths?

Zone and Sounder.

Have you disconnected the earth lead from the pcb? - Pete

Have you disconnected the earth lead from the pcb? - Pete

No

did the same myself, thinking old cable etc etc

disconnected and fine since (9 months+)

ti's all a learning curve

If it stays up then eliminate by disconnecting field wiring per output/input (sounder/zone) - disconnecting panel earth only removes the panels earth fault reference and hasn't cured the fault.If the panel still shows an earth fault and you have eliminated ALL field wiring (inc. mains supply) then the panel is at fault.

The fault is there for a reason.

Back to basics, Quickest way on a small system is to put EOL devices in at panel and prove panel. Then Put each zone/sounder back in one by one. Then you have a reference point.

Oxo, its intermitant. if its not there your cant find it. Had a similar problem myself on a much bigger scale with a morley Zx5.

Oxo, its intermitant. if its not there your cant find it. Had a similar problem myself on a much bigger scale with a morley Zx5.

All I suggested was to prove the panel.

Then the fun can start, or do you chase your tail for the first hour