PVC Conduit between panelboards

[iblittljn]

We are designing a 1-story detached accessory building as part of a residence. The accessory building will be used for work shop, home office and garage. The accessory building will have 3 100A 120/240 1ph panelboards installed on outer walls for ease of branch circuit wiring. One for terminating the feeder circuit from the main house and two more elsewhere in the building.

Conductors between panelboards are #2 THWN for hot and neutral and #8 THWN for ground and are run along truss members or perpendicular to the members along the outer walls, in the attic of the building.

I am told that I need to run the interpanel conductors in conduit but I cannot find a reference for that requirement in the 2005 NEC.

Can someone provide me a citation for the requirement if it exists?

Thanks.

Ian Littlejohn

 

[augie47]

Re: PVC Conduit between panelboards

I read this 3 times before I caught the question....
you are putting us on aren't you ?

 

[roger]

Re: PVC Conduit between panelboards

I agree with Augie, is this a real question?

Roger

[ August 16, 2005, 08:14 AM: Message edited by: roger ]

 

[sceepe]

Re: PVC Conduit between panelboards

I see from your profile that you are an EIT. I recommend that you run this by the PE who is overseeing your work. He should be able to help you.

 

[augie47]

Re: PVC Conduit between panelboards

EIT? Sounds more like HIT (Homeowner-In-Training), but, giving you the benfit of the doubt (assuming EIT is Engineer.....IT), NEC 300.3
I believe will answer your question.

 

[petersonra]

Re: PVC Conduit between panelboards

From the title of his question I was wondering if what he really meant was that the wiring was done in PVC conduit and it's now being stated that it has to be run in metal conduit. just a thought.

 

[dillon3c]

Re: PVC Conduit between panelboards

If came back to this post,more than once to stare.

Have you run these feeder conductors,in a cable assembly W/ sheath,and just need protection from physical damage,running exposed (surface) up the wall.

*I don't mean to insult your intelligence, but certainly you have not ran single conductor wiring,without benefit of raceway.

I'm just not, following your post..

Noted: its still early, in the morning..

[ August 16, 2005, 09:53 AM: Message edited by: dillon3c ]

 

[iblittljn]

Re: PVC Conduit between panelboards

The process is in the design phase not installation/implementation phase.

I saw 300.3 and using Charleie's Rule of Technical Reading, the NEC cite tells me that if a raceway etc is used, single circuit conductors cannot be separated into 2 or more raceways, trenches etc. They must all be installed together as a unit, which makes perfect sense.

It did not tell me that single conductors SHALL BE INSTALLED into a raceway etc.

Thanks for the help

Ian

 

[dillon3c]

Re: PVC Conduit between panelboards

(shaking my head)- starting off to be, a entertaining tuesday morning..


*I must need more coffee..later*

 

[charlie b]

Re: PVC Conduit between panelboards

OK guys and gals. We need to be nicer here. This is a young engineer; we should be supportive of young engineers (and electricians) who come to this site for help.

I think this is a fair question, particularly when you remember that the routing of cables and conduits is not included in any college's EE degree program. I must also admit that I find it to be a poorly worded (i.e., confusing) question. I will try to ask it another way.
</font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Is there an NEC requirement that conductors must be run in conduit? That is, can we route conductors without (using Dillon's term) benefit of raceway?</font>

<font size="2" face="Verdana, Helvetica, sans-serif">In this specific case, he is talking about the conductors from one panel to the next. But we may expand the question to address conductors from one of the panels to a load within the building.

Ian: Did I express your question correctly? Is this what you were trying to ask?

 

[steve66]

Re: PVC Conduit between panelboards

300.3 does tell you that single conductors need to be installed as part of a recognized wiring method...i.e. raceway. You might want to read it again keeping in mind that "single conductors" means any of the wire types listed in 310.13 that aren't part of a cable assembly (like NM cable or UF feeders).

Steve

 

[dillon3c]

Re: PVC Conduit between panelboards

Gentlemen I meant no disrespect to thread author.My condolances,it really wasn't my intent.

EE's have my respect.We just didn't connect..

goodmorning..

 

[iblittljn]

Re: PVC Conduit between panelboards

Charlie B

I am only concerned about the interpanel conduit requirement.

The wiring methods and other sections of the NEC describe how to wire from panelboards to loads depending on the environmental conditions - hazardous or not, wet dry, damp, overhead, underground, type of load, subject to damage or not etc.

I seem to remember somewhere that single conductors greater than xx size can be run along members etc.

As mentioned before, 300.3 seems to address precluding the separating of a single circuit into more than 1 conduit; not requiring all single-wire circuit conductors be installed into a conduit.

I guess the consensus is - conduit is required.

I will reread the section and get the Code Official's take on it. That will pretty much settle it.

 

[macmikeman]

Re: PVC Conduit between panelboards

Here is an idea, just call your local electrical inspection authority for your area, and let them know you are thinking about running the feeders as conductors without a raceway. Let the rest of us know later how it works out.

 

[eprice]

Re: PVC Conduit between panelboards

iblittljn,

Let me take a shot at answering your question. 300.3(A) requires that single conductors be installed as a part of a recognized wiring method of chapter 3. Looking through all of the chapter three wiring methods, the only ones that I can see which use open conductors without a cable assembly or raceway of some sort, would be 394 Concealed Knob-and-Tube Wiring, 396 Messenger Supported Wiring, or 398 Open Wiring on Insulators. Looking at the uses permitted and uses not permitted sections for each of those wiring methods, it appears to me that none of of them can be used in the application you are inquiring about.

Edit for typos

[ August 16, 2005, 05:24 PM: Message edited by: eprice ]

 

[infinity]

Re: PVC Conduit between panelboards

I seem to remember somewhere that single conductors greater than xx size can be run along members etc.

Sounds like you're thinking about the running of a grounding electrode conductor which can be installed along the surface of a building if #6 AWG or larger. Look at 250.64(B).

 

[LarryFine]

Re: PVC Conduit between panelboards

How about another stab at it?

If you use single conductors, you need a conduit. Conduit is only an option for grounding electrode conductors, and then only in certain situations.

If you do not want to run conduit, you should be able to use SER cable, as well as a few others. You may also need sections of conduit for protection.

 

[benaround]

Re: PVC Conduit between panelboards

Gents,

392.3(1)

Single conductor cable size 1/0 or larger ,can be used in cable tray!

 

[benaround]

Re: PVC Conduit between panelboards

Should add: Industrial Only!!

 

[charlie b]

Re: PVC Conduit between panelboards

Yes. But a cable tray is a "raceway." The OP is talking about not using any kind of a raceway.