Fire Alarm grounding at tamper switch/PIV?

[skeshesh]

Good day everyone, hope all is well.

I have a plan check comment for a minor design we did. A new sprinkler riser is being installed at some point in a facility and tamper switch/flow switch have to be interfaced with the existing FA system. We called out monitor modules, contacts, what have you so no problem there. We received this comment: "Specify method of grounding on plan xxx clearly show point of grounding connection". I don't really understand this point. We're dealing with a 24VDC fire alarm signal here and I don't think grounding is required per 250.112(I) - we've also done plenty of FA work for various clients including schools and universities that go through several plan checking agencies and I had not encountered this comment in the past. Am I missing something here?

 

[nhfire77]

Good day everyone, hope all is well.

I have a plan check comment for a minor design we did. A new sprinkler riser is being installed at some point in a facility and tamper switch/flow switch have to be interfaced with the existing FA system. We called out monitor modules, contacts, what have you so no problem there. We received this comment: "Specify method of grounding on plan xxx clearly show point of grounding connection". I don't really understand this point. We're dealing with a 24VDC fire alarm signal here and I don't think grounding is required per 250.112(I) - we've also done plenty of FA work for various clients including schools and universities that go through several plan checking agencies and I had not encountered this comment in the past. Am I missing something here?

There is no terminals or places to ground a PIV tamper switch (flow switch yes, tamper no) Threading the tamper into the valve makes the switch case technically grounded, but that isn't what they are asking.

Sounds like someone is confused, time for phone call.

 

[WIMaster]

Good day everyone, hope all is well.

I have a plan check comment for a minor design we did. A new sprinkler riser is being installed at some point in a facility and tamper switch/flow switch have to be interfaced with the existing FA system. We called out monitor modules, contacts, what have you so no problem there. We received this comment: "Specify method of grounding on plan xxx clearly show point of grounding connection". I don't really understand this point. We're dealing with a 24VDC fire alarm signal here and I don't think grounding is required per 250.112(I) - we've also done plenty of FA work for various clients including schools and universities that go through several plan checking agencies and I had not encountered this comment in the past. Am I missing something here?

The FACP is required to be grounded with an EGC. It would be a violation of the listing to ground your shields/cable at the flow switches. This could cause unwanted current on the shield and EMI.

I don't think you are missing something. I would politely RFI this.

 

[RICK NAPIER]

NFPA 72 article 4.4.4.5 permits it but does not require it. Maybe you could find something in the fire alarm installation manuals that would tell you not to ground.

 

[skeshesh]

Thanks for the responses everyone. I did some further digging and obvious found nothing requiring it (although it's allowed as pointed out).
I called the plan checker. Turns out he's a plumbing engineer and not familiar with electrical. He admitted that he just copied some comments from other jobs and claimed they like to "throw the grounding note out there since it's a safety issue and there's liability" etc. Basically he didn't know what he was talking about and just copied a comment.
As pointed out the tamper does not have ground provisions. The flow switch does but I think it's because it has contacts rated for both 120/250VAC and 24VDC and the intent is not to ground it in the case we're discussing here. Still waiting to hear from the MFG about installation recommendation.

 

[steve66]

Thanks for the responses everyone. I did some further digging and obvious found nothing requiring it (although it's allowed as pointed out).
I called the plan checker. Turns out he's a plumbing engineer and not familiar with electrical. He admitted that he just copied some comments from other jobs and claimed they like to "throw the grounding note out there since it's a safety issue and there's liability" etc. Basically he didn't know what he was talking about and just copied a comment.
As pointed out the tamper does not have ground provisions. The flow switch does but I think it's because it has contacts rated for both 120/250VAC and 24VDC and the intent is not to ground it in the case we're discussing here. Still waiting to hear from the MFG about installation recommendation.

You should have told him that was quite a concidence, because you were actually a plumbing designer too, and you had just copied the plans from another project.