lightning protection system conductors

[bobsydnor]

Was on a service call the other day in a commercial bldg. Customer asks me to look at an unrelated problem. Shows me a bare copper conductor running along the interior finished surfaces of the bldg. I trace the conductor and find that it is part of the lightning protection system on the exterior of the bldg. I have never seen these conductors run in the interior of a bldg. before. Although I'm not a lightning expert and I haven't seen everything (yes! after 30 years), this seems to be a hazard to me. Any one know where to research this. I,m searching this site and looking in the NEC, can't find anything. Does NFPA 780 cover this? Any thoughts you guys have on this will be greatly appreciated. THANKS, Bob

 

[petersonra]

Re: lightning protection system conductors

It seems unusual for me as well. One would be inclined to think the idea would be to keep the lightning on the outside of the building rather than encouraging it to come inside.

 

[steve66]

Re: lightning protection system conductors

NFPA 780 covers installations of lightning protection systems. I took a breif look and don't see anything to prohibit this (but I didn't look through everything in there). The closest thing I found was:

3-4 Mechanical Damage or Displacement.
Any part of a lightning protection system that is subject to mechanical damage or displacement shall be protected with a protective molding or covering. If metal pipe or tubing is used around the conductor, the conductor shall be electrically connected to the pipe or tubing at both ends.

There is a lot about routing of conductors in regard to sharpness of bends, dead ends, and not making "U" or "V" 's with the wires.

Steve

 

[wirenut1980]

Re: lightning protection system conductors

NFPA 780 3.15.1 (2000 edition). I am assuming you are talking about the attic and not the basement. Considering it is finished like you said, I don't think this complies.

3.15.1 General Requirements covering exposed systems also shall apply to concealed systems, except conductors shall be permitted to be coursed under roofing materials, under roof framing, behind exterior wall facing, between wall studding, in conduit chases, or embedded directly in concrete or masonry construction. Where a conductor is run in metal conduit, it shall be bonded to the conduit at the point where it emerges from the conduit and at all locations where the conduit is not electrically continuous.

Considering it is finished like you said, I don't think this complies, if the conductor is run on the outside of the finished wall or ceiling.

 

[mweaver]

Re: lightning protection system conductors

not my area of expertise, but did a few projects requiring lighting protection.

A visit to Harger's website (harger.com) will reveal fittings especially designed for through the wall or roof penetrations.

example

http://www.harger.com/catalog2004/2_4_1.pdf


hope this helps
mweaver

 

[bphgravity]

Re: lightning protection system conductors

Not many jurisdictions adopt the NFPA 780 and therefore lightning protection systems (charge redistribution ssytems) can be installed pretty much anyway you want. The NEC does rovide a few conditional requirements. 250.60 and 250.106 for example.