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Lightning protection and fire sprinkler piping

C

cda

Sawhorse 123
Joined
Oct 19, 2009
Messages
20,963
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Basement
Looking at new building

And appears they clamped onto the fdc and drains on the exterior and lightning wire runs into the ground and to the roof.

Have not had to deal with lightning protection to much

But have not seen it tied to fire sprinkler pipe

Legal not legal.

Any problem???

Sure you are not suppose to ground to a system
 
Someone have a section of 13 where it says not to ground yo the system???

Not finding it
 
Found it for underground 10.6.8 nfpa 13 2002 edition

But nothing for aboveground
 
From NFPA-13 [ 2010 Edition ], Section 7.7.1.1.7: "Auxillary devices where hung from the

building structure, shall be supported independently from the sprinkler portion of the

system, following recognized engineering practices."

Does this work?

Also, Article 250.106 [ `08 NEC ] requires the Lightning protection system ground

terminals to be bonded [ i.e. - attached / connected ] to the building or structure

grounding electrode system. I did not see an exception to allow the attachment

/ "bonding" to the fdc / sprinkler piping.

cda,

If the grounding conductors are connected to the fdc / drain piping, couldn't a

lightning strike [ potentially ] disable the electrical controls / gauges at the

riser, thereby disabling the sprinkler system as a whole?

.
 
Last edited by a moderator:
NFPA 780 (Standard for the Installation of Lightning Protection Systems) requires grounded metal objects to be bonded to the lightning protection system to prevent sideflashes, induced currents, and other dangerous conditions. It also requires grounding electrodes that are dedicated to the lightning protection system, so piping, steel framing, etc., can't be used as a ground.
 
cda asked:

Well I also saw them attached to the rain down spouts????
Click to expand...
Doesn't mean that that is a compliant install. Check the NFPA 780 that Paul referenced earlier..
 
Section 10.6.8 of the NFPA 13 clearly indicates underground portions of the fire sprinkler system must be not be used to ground the electrical system. However, there is no language that would prevent the required bonding in accordance with Section 250.104 of the NEC or Section 4.14 of the NFPA 780 for lightning protection systems. In fact, section in the NFPA 13, 10.6.8.1 clearly indicates that nothing in the NFPA 13 is to prevent the required bonding of metal water piping systems above or below ground.
 
"""clearly indicates that nothing in the NFPA 13 is to prevent the required bonding of metal water piping systems above or below ground.""""

that is what I am finding, just want to make sure

this is a high dollar building and want to get it right, but also do not want a lightning bolt to back feed into the fire sprinkler system
 
From NFPA - 780, Section 4.9.10: "At least two down conductors shall be provided on any kind

of structure, including steeples."

.
 
Assuming this is a NFPA 780 compliant system, the Lighning Protection ground terminals you are seeing are completely separate from the electrical power system earth ground (See Paul Sweet's comment).

As Paul further indicated, the bonding is to keep all grounded metal components at roughly the same potential. The fire protection system is always somewhat grounded normally, even if it is served via plastic UG pipe. It is the "somewhat" part that is the problem. Unless the FP system is at the same potential as other, better grounded components, the energy of the lightning strike could jump around trying to find the best path to ground. It is the jumping around that creates problems.

Next question - what happens if lightning strikes and a pumper is hooked up? Better in a well bonded and grounded system than if the pumper and engineer happens to make a better ground path than the plastic water service.
 
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