parallel 4/0 alum for residential 400 amp service.water pipe full size grounding elec conductor plus ground rod #6, if icome into first 200 amp panel with these groundig elec conductors how do i bond the second main breaker 200 amp panel to these conductors? Is this considerd a tap ? main bonding jumper? and where is it in the code. I see info on a main bonding equipment jumper on supply side and load side but maybe this is a different question but i dont work commercial and am not familiar with the reason why you would need one on the supply side, i thought you only had an ungrounded and grounded on the supply side. Thank you
main bonding jumper
- Thread starter bond
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- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: main bonding jumper
Your question's kinda foggy. Are you really talking about a house? You make mention of commercial work at the end, and a 400 amp service is one heck of a house!
For a 400 amp residential service, you would need 600 MCM AL service entrance conductors (Table 310.15(B)(6)). Based on this wire size, you would need a 3/0 AL (or 1/0 CU) Water bond, per Table 250.66.
Any feeders after the service disconnect fall under Table 250.122. A 200 amp feeder would require a #6 CU or #4 AL grounding conductor. SE-R cable is predesigned with this purpose in mind.
If you do use parallel conductors for the SE conductors, you need to base the wire size on 310.16, and for 400 amps you'd need parallel 250's not 4/0. You need to use the 75C column for the conductors you use.
In any case, base your Water Bond on your service entrance conductors. Note that 250.66 (Service Ground) bases itself on wire size, whereas 250.122 (Feeder/Branch Circuit Ground) is based on the overcurrent device.
Hope that helps. Are you doing an apartment or something? 400 amps!
-George
[ December 04, 2004, 06:15 PM: Message edited by: georgestolz ]
Your question's kinda foggy. Are you really talking about a house? You make mention of commercial work at the end, and a 400 amp service is one heck of a house!
For a 400 amp residential service, you would need 600 MCM AL service entrance conductors (Table 310.15(B)(6)). Based on this wire size, you would need a 3/0 AL (or 1/0 CU) Water bond, per Table 250.66.
Any feeders after the service disconnect fall under Table 250.122. A 200 amp feeder would require a #6 CU or #4 AL grounding conductor. SE-R cable is predesigned with this purpose in mind.
If you do use parallel conductors for the SE conductors, you need to base the wire size on 310.16, and for 400 amps you'd need parallel 250's not 4/0. You need to use the 75C column for the conductors you use.
In any case, base your Water Bond on your service entrance conductors. Note that 250.66 (Service Ground) bases itself on wire size, whereas 250.122 (Feeder/Branch Circuit Ground) is based on the overcurrent device.
Hope that helps. Are you doing an apartment or something? 400 amps!
-George
[ December 04, 2004, 06:15 PM: Message edited by: georgestolz ]
bphgravity
Senior Member
- Location
- Florida
Re: main bonding jumper
I feel you have three choices.
1. Make the service grounding connection before the disconnects at one of the accesible locations. The meter enclosure for example.
2. Run a full sized GEC from the electrode to each disconnect enclosure.
3. Install tap conductors as permitted in 250.66(D).
I feel you have three choices.
1. Make the service grounding connection before the disconnects at one of the accesible locations. The meter enclosure for example.
2. Run a full sized GEC from the electrode to each disconnect enclosure.
3. Install tap conductors as permitted in 250.66(D).
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