Sizing Main Bonding Jumper When Conductors are in EMT vs Wireway

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Tainted

Tainted

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New York
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Engineer (PE)
I want to make sure I'm sizing the main bonding jumper correctly.
I want to bond the neutral to the enclosure of a 600A service switch.

Scenario 1:

2 sets of 4#350KCMILS copper in EMT conduits (for a total of 2 conduits) enter a 600A service switch.

I use table 250.102(C)(1) and see that #2 copper is the minimum required for the main bonding jumper.

Scenario 2:

2 sets of 4#350KCMILS copper in 1 wireway enter a 600A service switch.

Since it's in the same raceway I would have to multiply it by 2 to get 700KCMILS and that would give me 2/0 minimum required for the main bonding jumper?

Is scenario 1 sized correctly?
I am not sure about scenario 2.
 
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Are you sizing a Main Bonding Jumper for Service Equipment or secondary SDS ??
If so see Note 3. The MBJ size would be determined by the sum of the kcmils of the conductors per phase,.
In your case 2/0 based on 700 kcmil.
 
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Tainted said:
So this means for both scenarios 1 and 2 we must have 2/0 minimum since the total conductor area for each phase is 700KCMILS?
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Yes, the parallel conductors in separate raceways would have the same size MBJ requirement as those in a single raceway.
 
infinity said:
Yes, the parallel conductors in separate raceways would have the same size MBJ requirement as those in a single raceway.
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Ok thanks, this helped a lot. If this was not service entrance conductors, would both of my scenarios be correct?
 
Tainted said:
Ok thanks, this helped a lot. If this was not service entrance conductors, would both of my scenarios be correct?
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Yes, with the single raceway a single EGC would be required, parallel raceways one in each raceway.
 
Why did your service equipment not come with a main bonding jumper? Equipment that is listed as service equipment is required to have a factory supplied main bonding jumper.
 
don_resqcapt19 said:
Why did your service equipment not come with a main bonding jumper? Equipment that is listed as service equipment is required to have a factory supplied main bonding jumper.
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I think he is talking about the bonding jumper between the conduit and the service equipment
 
don_resqcapt19 said:
Why did your service equipment not come with a main bonding jumper? Equipment that is listed as service equipment is required to have a factory supplied main bonding jumper.
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Just as a supplementary main bonding jumper. Is it okay to have a supplementary main bonding jumper? And in reality I'm just providing it on my plans incase it doesn't come with it.

Dennis Alwon said:
I think he is talking about the bonding jumper between the conduit and the service equipment
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is that also known as the supply side bonding jumper? That becomes the same size as the main bonding jumper right?
 
Tainted said:
Just as a supplementary main bonding jumper. Is it okay to have a supplementary main bonding jumper? And in reality I'm just providing it on my plans incase it doesn't come with it.


is that also known as the supply side bonding jumper? That becomes the same size as the main bonding jumper right?
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If it doesn't come with a main bonding it does not comply with the product standard.
If you are installing supply side bonding jumper, it is sized per 250.102(C)(1), and that is the same that you would use for a main bonding jumper of the wire type.
 
Tainted said:
is that also known as the supply side bonding jumper? That becomes the same size as the main bonding jumper right?
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Yes and no. If you have a single raceway yes, if you have parallel raceways then no. The SSBJ for each raceway can be based on the size of the ungrounded conductors in each raceway which could make it smaller than the MBJ.
 
infinity said:
Yes and no. If you have a single raceway yes, if you have parallel raceways then no. The SSBJ for each raceway can be based on the size of the ungrounded conductors in each raceway which could make it smaller than the MBJ.
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If I'm sizing the supply SSBJ in service equipment, wouldn't the SSBJ have to be the same size as MBJ? I thought note 3 applies to SSBJ too and not just the MBJ
 
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