C K Wrote:The fire alarm panel has a ground fault. How do I trouble shoot a ground fault?
Douglas Krantz Wrote:Troubleshooting a ground fault is like troubleshooting anything else. The first thing to do is stop and think. Ask yourself "What are you looking at?"
Troubleshooting requires the use of a guess-and-confirm, divide-and-conquer process. There is no single way of finding the problem. Each problem is unique and often the troubleshooting procedures lead down dead end roads. If one method of troubleshooting isn't you getting anywhere, try another method.
Ground Fault LightThe ground fault light on the panel can only tell you that something is wrong; somewhere, anywhere inside the panel or in the building outside the panel, electricity is leaking to ground.
The ground fault light cannot tell you if:
MetersInstead, find a more reliable way to detect the ground fault. Start by measuring the DC voltage of the battery terminals to ground. They are connected to the plus and minus circuits of the power supply and the battery terminals can give you a good indication of what the panel is seeing. Of course you have to be familiar with the manufacturer and model of the panel to know what is a normal reading and what is not normal because every model is a little different.
If that doesn't work, use another method.
Multiple MetersThere are 4 types of meters that are commonly used in troubleshooting ground faults.
Divide-and-ConquerTroubleshooting uses a Divide-and-Conquer technique: put a division between the part of the system that's good and the ground fault. Take pictures and mark wires to make sure you can get them back exactly where you disconnected them, but remove loops of wires and check to see if the ground fault goes away.
Remember - don't use the ground fault light-- it's a real bad troubleshooting indicator; use the meter to see if the ground fault is gone.
PatienceUsing the guess-and-confirm, divide-and-conquer process, the ground fault can and eventually will be found. The hard part is acquiring the required patience for the troubleshooting -- have patience and patience will come.
After finding and fixing dozens to hundreds of ground faults, you will be able to find most ground faults quickly.