Fire Riser

[NorthwestPV]

We are doing a TI in a building where another electrician wired the shell along with the service. They did not run a ground for the fire riser. My question is, can we attach this to the building steel or does it have to run back to the service?

 

[gadfly56]

We are doing a TI in a building where another electrician wired the shell along with the service. They did not run a ground for the fire riser. My question is, can we attach this to the building steel or does it have to run back to the service?

What components exactly comprise the "fire riser"? That's typically just the SLC and NAC's going to the upper floors.

 

[luckylerado]

We are doing a TI in a building where another electrician wired the shell along with the service. They did not run a ground for the fire riser. My question is, can we attach this to the building steel or does it have to run back to the service?

I would say that if the building steel is considered a grounding electrode per 250.52(A)(2) then you would be able to tie back to the steel. Look at 250.104 to figure out the size of the conductor for your situation.

Be mindful of any cathodic protection that might be in place where the riser emerges from grade and realize that NFPA 13 prohibits the underground piping system from being used as the grounding electrode.