Lightning damage to fire alarm control panels

[jbelectrical]

I am involved in a project with a fire alarm system configured in a campus-style arrangement amongst several buildings. One fire alarm control panel is installed at each building, and all are networked in what I am assuming is an NFPA Class B (non-redundant) configuration. Two of the fire alarm control panels have been repaired or replaced several times already, suffering component failure during or immediately after severe lightning storms.

Is this is an issue of improper grounding? An improperly installed lightning protection system? To the best of my knowledge, line voltage surge suppression equipment is installed at each panel. No form of protection is provided at communications interfaces. What are some other possible causes?

Thanks,

 

[rbulsara]

Besides checking the grounding, LP system and TVSS you mentioned, you will also need TVSS on any copper connections to the FACP that go out of the building. Meaning provide the appripriate TVSS on data lines, singalling lines that may be exposed or going out the building.

You may need to take a hard look as how the FACP is bonded to the ground. Make sure it is firmly bonded to a good electrode like a building steel. If the grounding system electrode has high resistivity, the lightning currents tend to create high voltage rise at the grounding electrodes and if the FACP (or any panel with sensitive electronics) is bonded via a small wire very close to such an electrode, it results in type of situaitons you describe.

Some times altering the grounding conneciton point that is less likely to see such voltage rises would resolve the issue.