Equipment grounding conductor

[samamelectric]

I have several 5000amp circuits that I am installing in cable tray. The equipment grounding conductor is supposed to be 700kcmil. I cannot find in the NEC where I can use 2-350kcmil cables instead. is this legal?

 

[jumper]

I do not think you can use 2 #350 instead of a single #700.

(F) Conductors in Parallel. Where conductors are installed
in parallel in multiple raceways or cables as permitted in
310.10(H), the equipment grounding conductors, where used,
shall be installed in parallel in each raceway or cable. Where
conductors are installed in parallel in the same raceway, cable,
or cable tray as permitted in 310.10(H), a single equipment
grounding conductor shall be permitted. Equipment grounding
conductors installed in cable tray shall meet the minimum
requirements of 392.10(B)(1)(c).
Each equipment grounding conductor shall be sized in
compliance with 250.122.

 

[bob]

(F) Conductors in Parallel. Where conductors are installedin parallel in multiple raceways or cables as permitted in
310.10(H), the equipment grounding conductors, where used,
shall be installed in parallel in each raceway or cable. Where
conductors are installed in parallel in the same raceway, cable,
or cable tray as permitted in 310.10(H), a single equipment
grounding conductor shall be permitted. Equipment grounding
conductors installed in cable tray shall meet the minimum
requirements of 392.10(B)(1)(c).
Each equipment grounding conductor shall be sized in
compliance with 250.122.

This post says that "a single EGC shall be permitted". Unless the code forbids it I believe that you can use 2 350 kcm as the EGC. 250.122 requires the EGC to be equal to 700 kcm. Maybe there is a statement that forbids the use of parallel conductors but it has not been shown so far.

 

[Volta]

This post says that "a single EGC shall be permitted". Unless the code forbids it I believe that you can use 2 350 kcm as the EGC. 250.122 requires the EGC to be equal to 700 kcm. Maybe there is a statement that forbids the use of parallel conductors but it has not been shown so far.

You might be right as it is actually written, but it is probably read as not permitting it, else we could parallel conductors smaller than 1/0 per 310.4(A), which is not written with complete logic either.

 

[jumper]

This post says that "a single EGC shall be permitted". Unless the code forbids it I believe that you can use 2 350 kcm as the EGC. 250.122 requires the EGC to be equal to 700 kcm. Maybe there is a statement that forbids the use of parallel conductors but it has not been shown so far.

How would you comply with the last sentence? You need a full sized EGC in each pipe.

 

[jumper]

You might be right as it is actually written, but it is probably read as not permitting it, else we could parallel conductors smaller than 1/0 per 310.4(A), which is not written with complete logic either.

The parallel EGCs can be smaller than 1/0, they just have to be be full sized according to T250.122 in each pipe.

 

[Volta]

The parallel EGCs can be smaller than 1/0, they just have to be be full sized according to T250.122 in each pipe.

Well, I'm just referring to the fact that nothing actually is written that forbids paralleling say, two #3 cu conductors for a 200a circuit, but we pretend that there is.

Seems similar to the OP's concern.

 

[bob]

There is a rule that says 1/0 is the smallest conductor that can be paralled. I can not quote right now.

 

[Volta]

There is a rule that says 1/0 is the smallest conductor that can be paralled. I can not quote right now.

Might be thinking about 310.4 Conductors in Parallel.
(A) General. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger comprising each phase, polarity, neutral, or grounded circuit conductor shall be permitted to be connected in parallel (electrically joined at both ends).

The 2 exceptions following similarly have only positive language, not a single "shall not" in the sub-section.

But we know what they mean. It is just a related example of language very much like that in the OP.

 

[Volta]

Neither are EGCs actually forbidden in the above sub-section, the the absence of them in the list is hard to overlook.

 

[jumper]

There is a rule that says 1/0 is the smallest conductor that can be paralled. I can not quote right now.

That does not apply to EGCs in parallel.

(H) Conductors in Parallel.
(1) General. Aluminum, copper-clad aluminum, or copper
conductors, for each phase, polarity, neutral, or grounded circuit
shall be permitted to be connected in parallel (electrically
joined at both ends) only in sizes 1/0 AWG and larger where
installed in accordance with 310.10(H)(2) through (H)(6).

(5) Equipment Grounding Conductors. Where parallel
equipment grounding conductors are used, they shall be sized
in accordance with 250.122. Sectioned equipment grounding
conductors smaller than 1/0 AWG shall be permitted in multiconductor
cables in accordance with 310.104, provided the
combined circular mil area of the sectioned equipment
grounding conductors in each cable complies with 250.122.

 

[jumper]

Here is a MH link that says the same thing.

http://www.mikeholt.com/instructor2/img/product/pdf/1220452732sample.pdf

 

[Volta]

Here is a MH link that says the same thing.

http://www.mikeholt.com/instructor2/img/product/pdf/1220452732sample.pdf

Well, figure 6-11 wasn't posted, so I didn't see it, but IMO, what he wrote is wrong. The wording of sub-section (E) uses the same lack of actual logic as does (A), or 250.122(F).

And whether it helps or not, the text

"Where conductors are installed in parallel in the same raceway, cable,
or cable tray as permitted in 310.10(H), a single equipment
grounding conductor shall be permitted. Equipment grounding
conductors installed in cable tray shall meet the minimum
requirements of 392.10(B)(1)(c).",

was removed from 2008 250.122(F).

But that doesn't logically matter.
It still does not say "shall not" for paralleling.

 

[jumper]

This seems pretty clear to me:

Each equipment grounding conductor shall be sized in
compliance with 250.122

Nothing about paralleling 2 conductors to make an equivalant conductor.

 

[Volta]

This seems pretty clear to me:

Each equipment grounding conductor shall be sized in
compliance with 250.122

Nothing about paralleling 2 conductors to make an equivalant conductor.

Permissive code. Otherwise, if specifically prohibited it uses the term 'shall not' 90.(A).

If that phrase isn't used, it is not prohibited.

 

[Dennis Alwon]

This is an interesting question and I have changed my mind 3 times. I tend to feel that the egc cannot be paralleled unless each run is the same size as Table 250.122 states. No where does it state T. 250.122 or equivalent except in the case of cables-- 310.4(E) - 2008

 

[Volta]

And don't get me wrong, I believe that the intent of say, 310.4 is to disallow paralleled conductors of smaller than 1/0, and I wire things that way.

I just don't think the text actually logically forbids it. Same with EGCs in 250.122(F), though honestly I have given them much less thought before now.

 

[jumper]

Permissive code. Otherwise, if specifically prohibited it uses the term 'shall not' 90.(A).

If that phrase isn't used, it is not prohibited.

Paralleling conductors " shall be permitted...only" in 2011 code.

(H) Conductors in Parallel.
(1) General. Aluminum, copper-clad aluminum, or copper
conductors, for each phase, polarity, neutral, or grounded circuit
shall be permitted to be connected in parallel (electrically
joined at both ends) only in sizes 1/0 AWG and larger where
installed in accordance with 310.10(H)(2) through (H)(6).

 

[Volta]

Paralleling conductors " shall be permitted...only" in 2011 code.

(H) Conductors in Parallel.
(1) General. Aluminum, copper-clad aluminum, or copper
conductors, for each phase, polarity, neutral, or grounded circuit
shall be permitted to be connected in parallel (electrically
joined at both ends) only in sizes 1/0 AWG and larger where
installed in accordance with 310.10(H)(2) through (H)(6).

Yay- now that's what I've been waiting for! Thanks!

 

[jumper]

Yay- now that's what I've been waiting for! Thanks!

It was Don G.s proposal that got it changed.