micmurphy65
New member
A question was posed to me regarding grounding requirements for the installation at a junior high school of a large solar voltaic system on a standing seam roof and I am posting the inquiry as it came to me while I am researching the answer.
A contractor is installing a thin membrane glue down type of solar voltaic system, this particular system can generate about 150kW at peak It is currently about 80% completely installed on a standing seam roof. It was observed that the metallic roof is completely isolated from any contact with building steel or any other elements that would be normally bonded to the EGC. This particular building structure is all steel, the structural part of the roof is wood fastned to purlins, there is a rubber like membrane on the wood and the channel that secures the standing seam roof panels are only connected to the wood, the entire metallic parts of the roof are floating except for the connection at the eaves and the ridge.
The concern from the contractor and local inspector is that there are galvanized rigid down spouts at all corners of the building that have good connection to the roof but are also isolated from any good connection to ground so there is the possiblity that an electrical failure that does not clear properly in any of system components installed (including some HVAC) on the roof could energize the roof sytem and the down spouts and create a condition where there a person could complete a ground path by touching the down spout.
The difficulty is in the determination of what is an adequate grounding method of the existing standing seam roof system, and where would one find language in the code to address this installation. Before the contractor starts bonding every other panel together with a bolted connection through every other seam I would like to get some feed back on any other experience other people have had with similar installations.
A contractor is installing a thin membrane glue down type of solar voltaic system, this particular system can generate about 150kW at peak It is currently about 80% completely installed on a standing seam roof. It was observed that the metallic roof is completely isolated from any contact with building steel or any other elements that would be normally bonded to the EGC. This particular building structure is all steel, the structural part of the roof is wood fastned to purlins, there is a rubber like membrane on the wood and the channel that secures the standing seam roof panels are only connected to the wood, the entire metallic parts of the roof are floating except for the connection at the eaves and the ridge.
The concern from the contractor and local inspector is that there are galvanized rigid down spouts at all corners of the building that have good connection to the roof but are also isolated from any good connection to ground so there is the possiblity that an electrical failure that does not clear properly in any of system components installed (including some HVAC) on the roof could energize the roof sytem and the down spouts and create a condition where there a person could complete a ground path by touching the down spout.
The difficulty is in the determination of what is an adequate grounding method of the existing standing seam roof system, and where would one find language in the code to address this installation. Before the contractor starts bonding every other panel together with a bolted connection through every other seam I would like to get some feed back on any other experience other people have had with similar installations.
