Douglas Krantz - Technical Writer - Describing How It Works
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Is it OK to Disconnect the Ground Fault Circuitry?

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I have a Question

Mr. Krantz

Hello. I was researching a ground fault issue my client is having with his plant fire alarm system and a VFD installed in the plant. Would you happen to have any experience with this sort of failure or could you recommend any resources relevant to this type of problem.

The electrician is suggesting we disconnect the FACP ground and I am strongly against that solution.

Any help would be greatly appreciated.

Thank you.

M C

Ground Fault Light

On all fire alarm panels there is a separate ground fault light. It's a warning light.

Fire alarm systems are property protection and life-safety systems. If something goes wrong with a fire alarm system, a fire starting in the building could burn it down, and lives could be lost. It's not the annoyance of the ground fault light that you need to be concerned with; if the ground fault is not fixed, it's the possible dangers that you need to be concerned with.

Ground Fault Danger

A ground fault is an electrical leakage to the building ground - somewhere in the building. With fire alarm systems, a single ground fault (electricity leaking to building ground) usually isn't a problem. At this point though, the ground fault light on the panel comes on to warn you of danger.

The danger is that a second ground fault can occur. A second ground fault completes the electrical circuit between the ground faults and causes one or more possible problems:
  • False alarms
  • Failure to detect fire
  • Shorted power supplies
  • Fire horns going off when nothing is happening
  • Fire horns not going off when there is a fire
  • Etc.

If the first ground fault is not fixed, these are all possible problems with the life-safety system. Disconnecting the Fire Alarm Control Panel (FACP) ground doesn't fix the ground fault; disconnecting the FACP ground will only prevent the fire alarm panel from warning anyone of the ground fault danger.

I suggest you contact a fire alarm service company familiar with finding and correcting ground faults in fire alarm systems.



Douglas Krantz
Having serviced fire alarm systems for nearly 20, Douglas Krantz has compiled his knowledge of the causes of Ground Faults and how to reliably detect them into the book Make It Work - Hunting Ground Faults. The book shows the three types of ground fault, what equipment should be used with each type of ground fault, and how to locate those hard-to-find ground faults.
Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer

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