ElectricNewEngland
Member
- Location
- New Hampshire
I'm trying to size the secondary side Equipment Grounding Conductor in a 225 kVA, 480V primary, 120/208V secondary to feed an 800A3P panel. I sized the secondary conductors to be 4 parallel sets of #3/0 copper wire, which is good for the 800A.
Now here is where I'm confused: Article 250.122(F) says "Each equipment grounding conductor shall be sized in compliance with 250.122." My first instinct is to use 4 parallel sets of #6 copper for the EGC because each one is good for 200A (in my mind, four of the EGCs good for 200A should be good for 800A) which I'm pretty sure is wrong because someone on this board said in an earlier topic that you cannot combine multiple small EGCs to make a larger EGC. I am also aware that article 310.10(H)(1)says that I cannot have parallel conductors smaller than 1/0 in each raceway.
So do I need 4 parallel sets of #1/0 AWG for my EGC? Having 4 parallel sets of #1/0 AWG EGCs for the feed to this 800A panel seems excessive since Table 250.122 indicates that one #1/0 AWG copper is good for 800A. Having 4 parallel sets of #1/0 seems like too much.
Now here is where I'm confused: Article 250.122(F) says "Each equipment grounding conductor shall be sized in compliance with 250.122." My first instinct is to use 4 parallel sets of #6 copper for the EGC because each one is good for 200A (in my mind, four of the EGCs good for 200A should be good for 800A) which I'm pretty sure is wrong because someone on this board said in an earlier topic that you cannot combine multiple small EGCs to make a larger EGC. I am also aware that article 310.10(H)(1)says that I cannot have parallel conductors smaller than 1/0 in each raceway.
So do I need 4 parallel sets of #1/0 AWG for my EGC? Having 4 parallel sets of #1/0 AWG EGCs for the feed to this 800A panel seems excessive since Table 250.122 indicates that one #1/0 AWG copper is good for 800A. Having 4 parallel sets of #1/0 seems like too much.
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