Conduit for Lightning Protection conductor

[anbm]

I saw all lightning protection details, where they have downlead conductor or through slab, sleeve, they always run this conductor inside PVC instead of a metal conduit. Is there any requirement these wiring need to be installed inside metal conduit? Just curious.

 

[jimday]

Check NFPA 780 "Standards for the Installations of Lightning Protection Systems". I belive you can install down conductors in metallic conduit as long as the conduit is bonded at each end (section 4.9.11). According to NFPA 780 4.9.14 you may still need to bond according to sections 4.19, 4.20, and 4.21 the requirement for bonding is "not eliminated" for non-metallic enclosures.....

 

[quogueelectric]

A ferrous conduit would create a choking effect on a strike current. If you bond it on both ends this should eliminate this but I am not sure if this is allowed in lightning protection.

 

[quogueelectric]

These folks will know for sure http://www.hearybros.com/

 

[jimday]

Check NFPA 780 section 4.9.11 and 4.19, 4.20, and 4.21.......

 

[anbm]

Thanks, does this mean PVC is okay to be used since NFPA 780 does not force to use metal?

 

[dereckbc]

Ferrous metal conduit would form a choke and make the conductor look like an open circuit making it useless. There are two work arounds:

• Use PVC
• Bond the conductor to th emetallic raceway.

 

[jimday]

NFPA 780 4.9.11.1 states that metallic guards shall be bonded at each end. 4.19 clarifies this by stating that metal bodies shall be bonded to the lightning protection system in accordance to 4.19, 4.20, and 4.21.....