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Joined: Oct 2000
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The main question: Is it a violation of any NEC article to terminate a conduit in one section of switchgear and land the wires in the section next to it?

Details: 2000amp 480volt main circuit breaker in section #1. Main feeds come in underground and the buss bars are up high. Section 2 is the distribution board with 7 - 400amp breakers (feeding 500MCM copper wire) and 8 smaller breakers. Section 2 is pretty full with wires.

The conduits in question are a 2 1/2inch with 4-500MCM feeding a rooftop air unit and a 3/4inch with 4-#12 feeding an exhaust fan.

The 500MCM in question are fed from the bottom left 400amp breaker of the distribution board, passing through to section 1 and are currently resting on the top buss bar.

Dennis E.

[Linked Image from electrical-photos.com]

[Linked Image from electrical-photos.com]

[Linked Image from electrical-photos.com]

[Linked Image from electrical-photos.com]


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This is the most quoted rule

Quote
312.8 Enclosures for Switches or Overcurrent Devices.
Enclosures for switches or overcurrent devices shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to other switches or overcurrent devices, unless adequate space for this purpose is provided. The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space.


... and it comes down to "unless adequate space for this purpose is provided".

This is generally a "I can't define it but I know it when I see it" sort of thing.


Greg Fretwell
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Is providing sufficient air gap between the wires and the buss adequate?

Would moving the 2.5" conduit forward by 3 or 4 inches be a suitable solution?

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[Linked Image from electrical-photos.com]

1st off, that red piece looks introduced, so methinks the adequate room ,if not "workmanlike" defintion might gain some legs on that alone

2nd, i'm not finding anything more than 3-500's in table C1

3rd, 500 cu per 310.15(b)(16) is good for 380A

10 lashes for the apprentice i say!

~S~


Last edited by sparky; 08/27/11 06:40 PM.
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As the conductor fill in the 2-1/2" conduit is in violation; correction of that has to be made. So, while increasing the conduit size, I would relocate it to the adjacent distro panelboard.

Is this gear a 'service'??

As observed from the pics, it appears that the conductors are within the barriered area (line side) of the main gear section.
This can be a POCO issue, IF the CTs are within the 'barriered section'. This could also be a violation for failing to follow mfg instructions.






John
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The bussing runs N - Top; then A,B,C - top down.

All of the Siemens 'big-boxes' I've installed (EUSERC) had a dedicated U/G pull section that took the bussing up high -- which feed a MAINS box -- with the current flowing from the Top down into the MAIN breaker -- thence off to bussing that exited low going to the various Distribution Boards.

These featured vertical bussing and 3 phase breakers mounted very much in the SqD I-Line style.

Your box appears to have a bottom to top current flow in the MAIN.

This would fail EUSERC standards.

Also, EUSERC would never permit your line side penetrations -- regardless of any other factor. It's space deeded over to the Poco -- and they don't want ANY customer circuits in their domain.

Where I come from the PM and Foreman would be pulled off the job/fired and the entire scheme re-worked.

BTW, on the load side, the bonding bushings make no sense.

The bonding conductor is improperly un-labled: it need be bare or banded green - -black doesn't cut it.

I see no provision for CT's or meters.

Is this, in fact, a sub-panel -- taking its power from a yet more powerful Distribution Board?

If this is the case, then the Poco is out of the picture, and you can get away with just re-routing the conductors -- per Code.

I still can't figure out how you're able to get away with reverse flowing the MAIN. That's a straight up Code violation -- right there.


Tesla
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Tesla:

Yes, a 'pull section' is common here also, along with line-top; load-bottom on CBs. However, a CB could be line-bottom, from the mfg.

Noting the barriers on the lower section of the main, I believe that is the 'line' side.

No provisions for CTs? I have come accross some that use 'donut' CTs out in the pad mount xfr, along with the meter at the xfr location. Not common, but I have seen it.

This also may be downstream from the MSB. Pehaps the OP could shed some more details on this.



John
Joined: Mar 2011
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Originally Posted by sparky


3rd, 500 cu per 310.15(b)(16) is good for 380A



Nothing wrong with that. Why did you post it as though it's a violation?

See 240.4(B)

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Originally Posted by Webmaster

The conduits in question are a 2 1/2inch with 4-500MCM feeding a rooftop air unit and a 3/4inch with 4-#12 feeding an exhaust fan.

Dennis E.


Why would a rooftop unit of that size require a neutral? Seems odd to me, units of that size should have integral control power transformers. Though I guess there could be 277V motors in it, seems unlikely.

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Is the conduit used as the grounding conductor?
I've always found it better practice just to run a seperate conductor out there, especially with loads of this size.


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