Bonding Piping Systems

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augie47

augie47

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I have been asked for an explanation of a grounding (bonding) situation that has been discussed here previously but am interested in any input/clarification so that I may pass it along.
The questions concern fire sprinkler systems and the question is three-fold:

250.52(A) requires underground metal piping systems to be used as grounding electrode with no particular reference to fire sprinkler systems in the NEC as far as I can determine.
It is my understanding that the sprinkler code (??) prohibits the system to be used "for grounding" (years ago when I had that Code available the wording was that "for grounding" not as an electrode..fine line).
So, do we address the metal underground fire sprinkler piping as required by 250.52(A) or not ?
Secondly 250.104 requires metallic piping systems be bondedl. If we don't follow 250.52 do we also exempt fire sprinkler systems from the 250.104 requirement,.
Third: Do the "groved couplings", where used, electrically isolate the sections of piping (sprinkler or other systems).
 
I was recently told at a job in providence RI that you can't bond the sprinkler main. The person who told me that, I don't take his word as gospel. Can anyone confirm? I don't see any reason, per the nec, to differentiate between an underground domestic water pipe and a sprinkler water pipe.
 
electrofelon said:
I was recently told at a job in providence RI that you can't bond the sprinkler main. The person who told me that, I don't take his word as gospel. Can anyone confirm? I don't see any reason, per the nec, to differentiate between an underground domestic water pipe and a sprinkler water pipe.
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Technically, unless a local amendment disallows like above, 250.104 says bond.

Many small buildings have an incoming water main that then splits to sprinkler pipes and domestic use. The main valve kills both, no isolation allowed.

We usually land the GEC there so the sprinkler system is bonded in a round about way.

For large buildings the water supply may be two different mains. We tag the domestic line, but not the sprinkler. Cannot use sprinkler main as an electrode.

When in doubt, ask CBO or FM, cause touching a sprinkler main is real iffy thing if you are flying blind.
 
Without reference to code, I feel that a sprinkler system that "may become energized" should be bonded to the grounding system. In many case this is done naturally by nature of building construction, but when the building is wood etc, then why wouldn't one want the sprinkler pipe to be bonded? If it was above ground and a hot wire shorted to it, it would be a death trap anywhere that is was accessible.
 
augie47 said:
2016 NFPA13
18.18.1 In no case shall sprinkler system piping be used for the grounding of electrical systems.
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That's 8.18.1 but if you read appendix A for section 8.18.2 it wil tell you:
While the use of the underground fire protectionpiping as the grounding electrode for the building is prohibited,
NFPA 70 requires that all metallic piping systems be
bonded and grounded to disperse stray electrical currents.
Therefore, the fire protection piping will be bonded to other
metallic systems and grounded, but the electrical system will
need an additional ground for its operation.
 
It's saying that the sprinkler system shall not be used to ground systems not that the sprinkler system should not be grounded.
 
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RICK NAPIER said:
It's saying that the sprinkler system shall not be used to ground systems not that the sprinkler system should not be grounded.
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If the sprinkler piping meets the requirement of 250.52, once you bond it, it would seem to be "grounding the system".
Which also takes me back to the grooved couplings often used on sprinkler piping. Do they interrupt electrical continuity between section of piping ?
 
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