# Grounding/bonding



## highlandele (Aug 9, 2008)

It's been a while since I've done some parallel runs.. What size wire do I need on my bonding bushings? Which table do I refer to? I have parallel 3/0 for a 400 amp service


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## MXer774 (Sep 1, 2014)

I'd go minimum #6 cu per run. Wrap around bonding bushing then land on EGC terminal. Call it done


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## cabletie (Feb 12, 2011)

I would use #4 copper to each bushing or #1/0 if the two bushings at conected together and brought to ground. 

250.102(c)
(2) Size for Parallel Conductor Installations. Where the 
ungrounded supply conductors are paralleled in two or more 
raceways or cables, and an individual supply-side bonding 
jumper is used for bonding these raceways or cables, the size 
of the supply-side bonding jumper for each raceway or cable 
shall be selected from Table 250.66 based on the size of the 
ungrounded supply conductors in each raceway or cable. A 
single supply-side bonding jumper installed for bonding two 
or more raceways or cables shall be sized in accordance with 
250.102(C)(1). these raceways or cables, the size 
of the supply-side bonding jumper for each raceway or cable 
shall be selected from Table 250.66 based on the size of the 
ungrounded supply conductors in each raceway or cable. A 
single supply-side bonding jumper installed for bonding two 
or more raceways or cables shall be sized in accordance with 
250.102(C)(1).


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## robertmorkel (May 18, 2015)

Assuming service conduits, it depends on how you install the conductor. If you loop one conductor and catch all bushings then you need to add the total kcmil of one phase conductor in each conduit and size the single jumper per 250.66 unless the sum goes over 1100kcmil (cu) then it;'s 12=1/2% (see 250.102)
If you run and individual bond to each bushing then it's sized per 250.66 for the parse conductor in the individual conduit.


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## wildleg (Apr 12, 2009)

MXer774 said:


> I'd go minimum #6 cu per run. Wrap around bonding bushing then land on EGC terminal. Call it done


interesting. how did you come up with #6 ?


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## Ontario (Sep 9, 2013)

Use #4 copper. I believe the rules for grounding/bonding in the Canadian and American code are very similar.


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