Equiptment Bonding Jumpers & Equiptment Grounding Co

[pattbaa]

Does the minimum-size (1/0) requirment of Art 310.4, Conductors in Parallel, apply to Equiptment Bonding Jumpers connected on the Supply-Side of the Service Dis-Connect(s)?

Art 251.102, Equiptment Bonding Jumpers, (C),Size-Equiptment Bonding Jumpers on the Supply-Side of the Service. reads---- "When the Service Entrance Conductors are parallel in 2 or more Raceways----the size of the Bonding Jumper for each Raceway shall be based on the size of the Service Entrance Conductor in the Raceway."

On the basis of this Art., the size of the Bonding Jumper is determined by referring to Table 250.66

Art 310.4 refers to Equiptment Grounding Conductors for installations with circuit-conductors connected in parallel.The size of this specifc type of Equiptment Grounding Conductor is determined by referring to Table 250.122

I pose this question because in the book "Electrical Grounding" the author, Ronald O'Riley, presents an "example" of parallel Service Conductors arranged in two 350mcm/ per-phase in 2 raceways.

Table 250.66 lists a #2 Bonding Jumper for each raceway, based on a 350MCM conductor,but O'Riley refers to the 1/0 minimum requirement of Art 310.4 and rejects the #2 conductor, and the "example" shows a 1/0 Equiptment Bonding
Jumper.

As best I know, the only reference in Art 310.4 to a specifc type of non-circuit conductor is to an Equiptment Grounding Conductor, as distinguished from a Equiptment Bonding Jumper.

With appreciation, Proud And Thankful----

 

[tom baker]

Re: Equiptment Bonding Jumpers & Equiptment Grounding Co

On the supply side of a service its not an equipment grounding conductor, its the grounded conductor, and section 250.66 applies. Here you are sizing per the size of the ungrounded condutors, not the OCPD. However the equipment grounding conductor for an equal size installation line to load, in parallel, will typically be larger.

"Table 250.66 lists a #2 Bonding Jumper for each raceway, based on a 350MCM conductor,but O'Riley refers to the 1/0 minimum requirement of Art 310.4 and rejects the #2 conductor, and the "example" shows a 1/0 Equiptment Bonding
Jumper." This is correct. On a feeder the fault current can feed from each end so a full size EGC is used.
You can't really compare the line and load side, its two different applications.

 

[pattbaa]

Re: Equiptment Bonding Jumpers & Equiptment Grounding Co

"On the Supply-side of thr Service, it's not an Equiptment Grounding Conductor, it's the Grounded conductor"

My question pertains to Equiptment Bondings Jumpers, Art 250.102, not EGC's, and it's also the Grounded Conductor on the Load-side of the Service---Most Feeders and Branch-Circuits have a Grounded Conductor.

"you can't compare the Line and Load side----"

I'm well aware of that distinction----250.102 (C) and 250.102(D).

"On a Feeder the fault-current----"

My question pertains to Service-Entrance Conductors, not Feeder conductors.

I hope I ask a simple question----Does the minimum-size requirement of Art.310.4 apply to Equiptment Bonding Jumpers?--- Can two #2 Equiptment Bonding Jumpers connected "in parallel" be used for Bonding the enclosures and raceways of a Service with two 350MCM Service Entrance Conductors connected in parallel?

 

[websparky]

Re: Equiptment Bonding Jumpers & Equiptment Grounding Co

Can two #2 Equiptment Bonding Jumpers connected "in parallel" be used for Bonding the enclosures and raceways of a Service with two 350MCM Service Entrance Conductors connected in parallel?

Yes.

[ March 10, 2004, 06:40 PM: Message edited by: websparky ]