LIGHTNING PROTECTION

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Recently our general contractor installed a lightning protection system which is on an explosive dust building through his sub-contractors and a 2nd tier lightning protection sub contractor designer and UL certified LP Master Certifier. Mainly this is a contract issue, the contract calls for copper LP system as a whole, ground girdle , down conductors and top side LP system. For the LP system they installed Aluminum conductors on the roof saying this is the only way the UL Lightning Protection Master Certifier could install the system to certify the LP system.

So, the mechanical system, roof flashing and down spouts are sheet metal and other dissimilar metals. There position is AL conductors were used to reduced galvanic action across all the equipment on the roof. I have read in NFPA 780 copper should not be in contact with aluminum . Does this requirement copper can't not be used at all or stainless steel connectors at the dissimilar metals should be used for the galvanic action?

NFPA 780 4.2.2.3 Aluminum.
4.2.3 Copper lightning protection materials shall not be installed
on or in contact with aluminum roofing, aluminum siding,
or other aluminum surfaces.

Also the UL Master Certifier may not know the building the building the building houses explosive dust. The Certifier is required to design to UL 96A Standard for Lightning Protection Systems.

UL 96 A Scope 1.1 These requirement cover the installation of lightning protection systems on all types of structures other then used for production, handling, or storage of ammunition, explosives, flammable liquids or any other explosive ingredients including dust.
 
Recently our general contractor installed a lightning protection system which is on an explosive dust building through his sub-contractors and a 2nd tier lightning protection sub contractor designer and UL certified LP Master Certifier. Mainly this is a contract issue, the contract calls for copper LP system as a whole, ground girdle , down conductors and top side LP system. For the LP system they installed Aluminum conductors on the roof saying this is the only way the UL Lightning Protection Master Certifier could install the system to certify the LP system.

So, the mechanical system, roof flashing and down spouts are sheet metal and other dissimilar metals. There position is AL conductors were used to reduced galvanic action across all the equipment on the roof. I have read in NFPA 780 copper should not be in contact with aluminum . Does this requirement copper can't not be used at all or stainless steel connectors at the dissimilar metals should be used for the galvanic action?

NFPA 780 4.2.2.3 Aluminum.
4.2.3 Copper lightning protection materials shall not be installed
on or in contact with aluminum roofing, aluminum siding,
or other aluminum surfaces.

Also the UL Master Certifier may not know the building the building the building houses explosive dust. The Certifier is required to design to UL 96A Standard for Lightning Protection Systems.

UL 96 A Scope 1.1 These requirement cover the installation of lightning protection systems on all types of structures other then used for production, handling, or storage of ammunition, explosives, flammable liquids or any other explosive ingredients including dust.

Just to make sure I understand you correctly. The building has a metal roof, and the installer used aluminum materials on top of the roof to protect against electrolysis? If this is the case then yes, they had to install this way in order to meet code. There really is no getting around it on a metal roof, the system must be aluminum, but the rest of the system should still be copper, depending on how the down conductors were run.

As far as the inspection goes, while UL will not certify structures that house flammable materials to the 96A standard, they will inspect and certify the system to the NFPA 780 standards, and this should be acceptable as it is essentially the same requirements. But a lot of times the inspector does not know if the structure will house explosive materials, and it is up to the lightning protection contractor to let them know and have it certified to the correct standard.
 
Just to make sure I understand you correctly. The building has a metal roof, and the installer used aluminum materials on top of the roof to protect against electrolysis? If this is the case then yes, they had to install this way in order to meet code. There really is no getting around it on a metal roof, the system must be aluminum, but the rest of the system should still be copper, depending on how the down conductors were run.

As far as the inspection goes, while UL will not certify structures that house flammable materials to the 96A standard, they will inspect and certify the system to the NFPA 780 standards, and this should be acceptable as it is essentially the same requirements. But a lot of times the inspector does not know if the structure will house explosive materials, and it is up to the lightning protection contractor to let them know and have it certified to the correct standard.


This is a commercial building with a PVC roof with a slight pitch.
 
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