psmpsm
Electrical
- Dec 19, 2022
- 35
Hello all. I had an approach to this question but wanted to see if I'm on the right track.
I'm dealing with a new high voltage cable installation in underground duct bank. 3 750mcm single conductor cables, each in their own conduit, laid in flat formation.
We are required to have an equipment grounding conductor which is transposed in order to provide a low impedance path to ground for a short circuit condition.
Question is, how do I size that EGC. I thought it was as simple as looking at Table 250.122 in the NEC. Based on that table, if the OCPD is set at 300A, I would be going for a #4 EGC.
However, I wasn't sure if Table 250.122 applies to high voltage, and also if there is a way for me to calculate currents expected to run through the EGC. Any suggestions please?
I'm dealing with a new high voltage cable installation in underground duct bank. 3 750mcm single conductor cables, each in their own conduit, laid in flat formation.
We are required to have an equipment grounding conductor which is transposed in order to provide a low impedance path to ground for a short circuit condition.
Question is, how do I size that EGC. I thought it was as simple as looking at Table 250.122 in the NEC. Based on that table, if the OCPD is set at 300A, I would be going for a #4 EGC.
However, I wasn't sure if Table 250.122 applies to high voltage, and also if there is a way for me to calculate currents expected to run through the EGC. Any suggestions please?