"Equipment Grounding Conductor" or "Bonding Conductor"

[vick67]

I copied this picture from an old closed thread and I have always had some confusion as to the name of the wire between the X0 and first ground bus. Should it be treated as an equipment ground and sized by 250.122 or a bonding ground and sized by 250.66?


View attachment 9071

Thanks for the replies.
Chad

 

[jwelectric]

250.30(A)(2) Supply-Side Bonding Jumper. If the source of a separately derived system and the first disconnecting means are located in separate enclosures, a supply-side bonding jumper shall be installed with the circuit conductors from the source enclosure to the first disconnecting means. A supply-side bonding jumper shall not be required to be larger than the derived ungrounded conductors. The supply-side bonding jumper shall be permitted to be of nonflexible metal raceway type or of the wire or bus type as follows:
(a) A supply-side bonding jumper of the wire type shall comply with 250.102(C), based on the size of the derived ungrounded conductors.
(b) A supply-side bonding jumper of the bus type shall have a cross-sectional area not smaller than a supply-side bonding jumper of the wire type as determined in 250.102(C).


250.102(C) Size ? Supply-Side Bonding Jumper.
(1) Size for Supply Conductors in a Single Raceway or Cable. The supply-side bonding jumper shall not be smaller than the sizes shown in Table 250.66 for grounding electrode conductors. Where the ungrounded supply conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, the supply-side bonding jumper shall have an area not less than 12? percent of the area of the largest set of ungrounded supply conductors.
(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).
(3) Different Materials. Where the ungrounded supply conductors and the supply-side bonding jumper are of different materials (copper or aluminum), the minimum size of the supply-side bonding jumper shall be based on the assumed use of ungrounded conductors of the same material as the supply-side bonding jumper and with an ampacity equivalent to that of the installed ungrounded supply conductors.

 

[GoldDigger]

250.30(A)(2) Supply-Side Bonding Jumper. If the source of a separately derived system and the first disconnecting means are located in separate enclosures, a supply-side bonding jumper shall be installed with the circuit conductors from the source enclosure to the first disconnecting means.

So that tells us what a Supply-Side Bonding Jumper is, and makes it clear that what the OP is asking about is not one. What do you call it?
Is it simply a GEC and nothing more?

 

[jwelectric]

So that tells us what a Supply-Side Bonding Jumper is, and makes it clear that what the OP is asking about is not one. What do you call it?
Is it simply a GEC and nothing more?

Do What??????????????

That is exactly what he is asking about in the picture

 

[GoldDigger]

Do What??????????????

That is exactly what he is asking about in the picture

To me, his description of "the wire between the X0 and the first ground bus" refers to the short wire inside the transformer (source) enclosure, not the one leading to the other enclosure (second ground bus.)
The second wire would be the S-SBJ.

 

[jwelectric]

From XO to the bus in the transformer is the system bonding jumper but the attachment shows a ? on the SSBJ

 

[Julius Right]

In my opinion, the secondary of the transformer it is a separately derived system. This conductor it is actually a system grounding conductor. In this case according to 250.28.(D).1 the size has to be according to Table 250.66, except if the supply conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, the bonding jumper shall have an area not less than 12 1?2 percent of the that is area of the largest phase conductor.
The Main bonding jumper -from the service- has to be sized also as per 250.28.(D).1.Table 250.122 it is only for equipment after a protecting device-after distribution 208/120 panel.
:happysad:

 

[GoldDigger]

From XO to the bus in the transformer is the system bonding jumper but the attachment shows a ? on the SSBJ

And in the other thread on the same subject, the OP corrected the wording from "from the X0 to the first ground bus" to "from the transformer ground bus to the first panel." Based on that you are exactly right, but the correction was never made in this thread.
Merge anyone?