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#28173 - 08/12/03 01:12 PM Phases in different raceways
mamills Offline
Member
Registered: 11/30/01
Posts: 745
Loc: Wharton, Texas, USA
Hi Guys (and ladies, of course): I need a little learnin' here. A church in this area is undergoing a service upgrade. There are four separate raceways being installed to provide a three phase service. Each one, equipped with weatherhead, travels along the back side of the church building for a distance of about 50 feet before elbowing through the wall into a switchgear room. So far, the conductors for the three hot legs (color-coded black, red and blue - three conductors per leg) have been pulled into the conduits. However, unlike what I've read, and seen discussed here previously, all three black legs are in one conduit, all three reds in another, and all three blues in the third (instead of one of each appearing in each conduit). The fourth conduit is empty at present - I assume that the "neutral" is supposed to go here.

I thought that this was strictly a NO-NO, and serious problems could result from this. Can y'all elaborate on this for me?

Mike (mamills)
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#28174 - 08/12/03 01:28 PM Re: Phases in different raceways
iwire Offline
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Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
.

[This message has been edited by iwire (edited 08-12-2003).]
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#28175 - 08/12/03 01:35 PM Re: Phases in different raceways
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
I have done similar installations underground but I do not believe you can do this aboveground look at the one exception for Paralleled Installations.

[quote]300.3 Conductors.

(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (4).

(1) Paralleled Installations. Conductors shall be permitted to be run in parallel in accordance with the provisions of 310.4. The requirement to run all circuit conductors within the same raceway, auxiliary gutter, cable tray, trench, cable, or cord shall apply separately to each portion of the paralleled installation, and the equipment grounding conductors shall comply with the provisions of 250.122. Parallel runs in cable tray shall comply with the provisions of 392.8(D).

Exception: Conductors installed in nonmetallic raceways run underground shall be permitted to be arranged as isolated phase installations. The raceways shall be installed in close proximity, and the conductors shall comply with the provisions of 300.20(B).

Bob
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#28176 - 08/12/03 01:38 PM Re: Phases in different raceways
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
Mike,
What are raceways made of?
Don
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#28177 - 08/12/03 01:45 PM Re: Phases in different raceways
mamills Offline
Member
Registered: 11/30/01
Posts: 745
Loc: Wharton, Texas, USA
Don;
They appear to be rigid steel pipe with threaded fittings. I'm guessing they are about 3 1/2 - 4" diameter.

Mike (mamills
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#28178 - 08/12/03 01:52 PM Re: Phases in different raceways
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Don would you be able to apply 300.3(B)(3) to a paralleled installation.


Bob
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#28179 - 08/12/03 03:07 PM Re: Phases in different raceways
Electric Eagle Offline
Member
Registered: 04/20/02
Posts: 914
Loc: Alpharetta, GA
I haven't personally seen an installation like this, but someone I know told me of a serious heat problem caused by the situation you described. Perhaps someone can elaborate on possible complications.
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#28180 - 08/12/03 03:25 PM Re: Phases in different raceways
PCBelarge Offline
Member
Registered: 06/08/03
Posts: 681
Loc: Dobbs Ferry, NY, USA
Bob

I would say based on 300.3(B)(1)exception, that the above installation is a violation, and it will definitely cause a heating of the conduit problem. Possibly causing a fire.
300.3(B)(3) does not pertain to paralleled installations.
Even if they had run PVC above grade, that is a violation.
I understand why some like to install a parallel service this way, it makes working with the conductors easier.

Pierre
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Pierre Belarge
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#28181 - 08/12/03 03:45 PM Re: Phases in different raceways
arseegee Offline
Member
Registered: 01/28/02
Posts: 324
Loc: Statesboro, GA USA
All i can say is stand back when they throw the main. Due to the magnetic field produced from the flow of electrons, you DO NOT want to install all the same phase conductors in there own pipe. I know a company that did that on a Kwickset factory not far from me. Blew the concrete wall off the back of the building. That was their first and last big job.

[This message has been edited by arseegee (edited 08-12-2003).]
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#28182 - 08/12/03 05:29 PM Re: Phases in different raceways
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
Bob,
In my opinion 300.3(B)(3)would permit this installtion if the raceways were nonferous. Note that you would have to comply with 300.20(B) where the conductors enter the panel. If these are ferous raceways, then the installation is a code violation and will fail very quickly when any load is applied.

Pierre,
I see nothing in 300.3(B)(3) that says you can't use the section for parallel installations.

Don
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