Raceway Bonding

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DoubleD

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Service supplied by 3 metal raceways. Each contains 600 kcmil phase conductors. What is the size of the bonding jumper for each raceway and where is this in the NEC?
 
250.66 for service conductors. 250.122 for feeders or branch circuits. Metal raceways are suitable as grounding conductors themselves, so I am not real sure what you are asking.
 
600s

600s

assuming 1 of each phase per conuit, assuming copper, and assuming you are bonding each conduit seperately, a 1/0 Cu bond
 
This one is a Mike Holt question and the possible answers are

a) 3AWG cop
b) 4AWG cop
c) 4AWG alum
d) 3AWG alum

We think it may have to do with the 121/2% rule in Article 250 but still can't get any of the above answers. Our first choice was a 1/0 copper from the table...
 
Here is a question from Mike's Grounding versus Bonding book:


Q. What size bonding jumper is required for a metal raceway containing 600 kcmil service conductors?


(a) 1 AWG (b) 1/0 AWG (c) 2/0 AWG (d) 3/0 AWG


A. (b) 1.0 AWG, Table 250.66
 
I can't find it. I think the OP is asking where in the NEC does it tell you

where to look, or what table to use, for the conductor that loops from the

bonding bushing on the end of each of 3 metal service entrance raceways,

to the EG bus. I'm seeing 3 RMC's coming into a open bottom SES ea. has

a bond bushing, I can't find the words in the NEC for this situation .as to

how to size this bonding wire.

I always use 250.66, but this is not an electrode??
 
benaround said:
I can't find it. I think the OP is asking where in the NEC does it tell you

where to look, or what table to use, for the conductor that loops from the

bonding bushing on the end of each of 3 metal service entrance raceways,

to the EG bus. I'm seeing 3 RMC's coming into a open bottom SES ea. has

a bond bushing, I can't find the words in the NEC for this situation .as to

how to size this bonding wire.

I always use 250.66, but this is not an electrode??
Click to expand...



I don't believe that this is code compliant on parallel service raceways. 250.102(C) requires the bonding jumper for each raceway to be sized according to the conductor size in each raceway.
 
The code reference is 250.102(C). This section referes to Table 250.66 for sizing bonding jumpers on the supply side of the service. The section does include the 12 1/2% rule, but since the 600 kcmil conductors are less than 1100 kcmil, that part of the rule doesn't apply. Note the last sentence of the section: "The size of the bonding jumper for each raceway or cable shall be based on the size of the service-entrance conductors in each raceway or cable".

Edit to fix a typo in the code reference.
 
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