Lightning Protection

Been digging through NFPA 780 and NEC, and can't find a requirement for our application.

We are building a steel reinforced concrete water treatment filter building approx 25' tall with a flat deck concrete roof that has 18' light poles on top. Nowhere in our prints or specs does it require a bond to the rebar or ground grid. It is the opinion of the inspection staff here that we should have a bond there to prevent a surge at the lighting panel and main switchgear through the equip bonding conductor.


I can't find any reqmts. Any help?

Thanks guys.
 

ron

Senior Member
NFPA 780 is not an adopted code in any jurisdiction that I'm aware, so no need to look there.

The NEC requires a grounding electrode system. It is only a few code cycles ago that it was required to bond to building footing steel. Ground rods and water pipes were all that was needed.
 
So rather than being code-required, you would consider this optional/supplementary protection?



NFPA 780 is not an adopted code in any jurisdiction that I'm aware, so no need to look there.

The NEC requires a grounding electrode system. It is only a few code cycles ago that it was required to bond to building footing steel. Ground rods and water pipes were all that was needed.
 

iwire

Moderator
Staff member
Location
Massachusetts
We are building a steel reinforced concrete water treatment filter building approx 25' tall with a flat deck concrete roof that has 18' light poles on top. Nowhere in our prints or specs does it require a bond to the rebar or ground grid. It is the opinion of the inspection staff here that we should have a bond there to prevent a surge at the lighting panel and main switchgear through the equip bonding conductor.
Even if you bond at each light pole if lighning strikes one you will still get a spike or surge back at the lighting panel.
 

Sahib

Senior Member
Location
India
So rather than being code-required, you would consider this optional/supplementary protection?
Yes. But you be careful lest it introduces any additional hazard. The steel frame in the concrete should be continuous. Any discontinuity could result in an explosion during lightning current flow through the steel frame.
 

cuba_pete

Senior Member
Location
Washington State
"Shall"

"Shall"

It has always been pretty clear to me. If you have a lightning protection system, the 250.106 in the NEC states:

The lightning protection system ground terminals shall be bonded to the building or structure grounding electrode system.

Seems pretty clear in theory and practice. Use 780 to implement and placate any AHJ.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
It has always been pretty clear to me. If you have a lightning protection system, the 250.106 in the NEC states:

The lightning protection system ground terminals shall be bonded to the building or structure grounding electrode system.

Seems pretty clear in theory and practice. Use 780 to implement and placate any AHJ.
If there is no LPS than what is there to bond?

Is there any applicable code or regulation that requires a LPS for this type of structure?
 

cuba_pete

Senior Member
Location
Washington State
If there is no LPS than what is there to bond?

Is there any applicable code or regulation that requires a LPS for this type of structure?
In my experience it depends on the manufacturer of the equipment installed within a facility/structure, but I am not in a lightning prone area and I work on Federal property, so we have different rules regarding LPS'. If the equipment requires it, to what extent, etc., then I would install according to 780 and bond according to the code (and other applicable references of the NEC).

There are some shalls in the NEC for lightning protection so, yes, there is an applicable code...NFPA 70. Your brief description of the structure isn't enough to make a determination. Depending on your state/locality the AHJ should be able to explain this pretty well.

If it's not in the engineering and design specifications then you pretty much have your answer. Again...AHJ.
 
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