Fellow Code Guru’s:
I have a question concerning the NEC's Article 250 stance on tying in new structures to existing. We have this Railroad elevated tie off structure that will allow the factory workers to tie off to an elevated rail and access the railcars as they enter the area. The owner wants to drive 20' ground rods adjacent to each steel beam on that structure. The structure is going into an area that has existing slabs that make running a ground ring difficult. I told them that they needed to tie opposing ends of the grounded columns to the nearest existing ground loop of an adjacent structure. They want to know why this is required. I know that the code requires all structures to have a ground loop with a maximum ground resistance of less than 25 ohms or less per 250.53 (2) Exception. One other caveat is that this structure does not have any electrical power requirements that are currently in the design parameters. I don't know if this has any bearing on the tie in to the existing structures or not. Any recommendations to my approach is greatly appreciated. Also could you please direct me to the area of the code that discussed tying in new structures to existing? If there isn’t a code reference then is this good engineering practice to tie them?
The whole reason is to protect the personnel from static discharge, and there could be some built up when they go to hook their lanyards onto the railcar support beams.
Thanks in advance for your input.
I have a question concerning the NEC's Article 250 stance on tying in new structures to existing. We have this Railroad elevated tie off structure that will allow the factory workers to tie off to an elevated rail and access the railcars as they enter the area. The owner wants to drive 20' ground rods adjacent to each steel beam on that structure. The structure is going into an area that has existing slabs that make running a ground ring difficult. I told them that they needed to tie opposing ends of the grounded columns to the nearest existing ground loop of an adjacent structure. They want to know why this is required. I know that the code requires all structures to have a ground loop with a maximum ground resistance of less than 25 ohms or less per 250.53 (2) Exception. One other caveat is that this structure does not have any electrical power requirements that are currently in the design parameters. I don't know if this has any bearing on the tie in to the existing structures or not. Any recommendations to my approach is greatly appreciated. Also could you please direct me to the area of the code that discussed tying in new structures to existing? If there isn’t a code reference then is this good engineering practice to tie them?
The whole reason is to protect the personnel from static discharge, and there could be some built up when they go to hook their lanyards onto the railcar support beams.
Thanks in advance for your input.
