What is the reason and how can you troubleshoot a ground fault alarm in a Fire Alarm System (FAS)?

A wire on one of the initiating or indicating circuits is touching ground.

Disconnect the wires from each zone one at a time until the ground fault goes away. The problem will be on that wire.

Check for corrosion on the batteries. Battery acid can eat through the paint and cause ground faults.

the reason for having a ground fault in the facp is because of poor wire dressing in newly installed fire alarm system. If it is old then you must check if there is a damage cable which is touching the ground or conduits. 

For the new installation, reason is that of poor installation practices while the old system practically wear and tear if not other factors that cause the ground fault, to troubleshoot the ground fault it is by isolation per segment starting from the FACP.

There are two types of GND faults, the first type can happened on field devices, this may be that device fully water or its board grounded, second type on loop cables and this type is common may be from cable is touching steels.

regarding how to solve, 1st type if your system is addressable it will give to you which device is grounding so you will replace, but if your system is conventional you divided the zone into two parts to check which part has ground device then check device one by one.

for second type will follow the following procedures:

• in case your loop connected as class A, you will convert it to  class B by release return cable.
• then you will divided the loop into two parts by half.
• if the first half is good you will increase more ten devices, and etc.
• till you will get ground in the part you add.
• check cables in this area.
• solve the cause for ground fault.

The ground faults in FAS may cause because of various reasons as mentioned by others above, could be because of poor wiring, poor dressing of cables, during installation of devices leaving cables more open by removing the insulation more than required which could touch the metals or cross over the terminals of connections. Also could be because of improper connections of grounding cables in the panel itself.

To troubleshoot ground faults in FAS, check the grounding cable connections done properly in the panel, then most importantly the wiring of devices loops should be checked thoroughly, to trace the fault easily, start checking the loops with first end and first 5 devices at first if not traced then go for the next 5 devices and keep going until the fault is traced. this will definitely trace out the location of fault.

If it is old then you must to be checked properly if there is a damage cable, wire which is touching the ground or  MS conduits Otherwise Fire panel suffering from Ground Fault.