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#97820 - 03/31/06 08:40 PM Type SO as building wiring  
maintenanceguy  Offline
Member
Joined: Dec 2001
Posts: 300
Southern NJ, USA
Called in our electrical contractor to give us a price on some work in several schools. I've had to call him back on a couple of projects lately and haven't been dazzled with the quality of his work. The "lowest bidder" rule in government contracting at its best.

Anyway...I want a new sub pannel installed in a school. I show him the switch gear, tell him where I want the new breaker installed, show where the EMT should go across a boiler room and into a hallway drop ceiling. I suggest that he can go to MC or greenfeld there since it will be out of site but I want EMT wherever we can see it.

He suggested switching from EMT to SO and running SO down the hallway to swith back to EMT where it becomes visable again. I told him I didn't want SO and he's going to quote greenfield but is SO even allowed?


2017 / 2014 NEC & Related Books and Study Guides

#97821 - 03/31/06 08:49 PM Re: Type SO as building wiring  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
This 'electrical contractor' is not an electrician.

Quote
400.8 Uses Not Permitted.
Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure


MC would make the most sense if not pipe.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#97822 - 03/31/06 09:56 PM Re: Type SO as building wiring  
renosteinke  Offline
Cat Servant
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Posts: 5,316
Blue Collar Country
The "lowest bidder" applies to the lowest QUALIFIED bidder. The guy you describe is a hack, and ought to be barred from all future bids.

He's also a financial idiot. SO cable is no bargain.


#97823 - 03/31/06 10:07 PM Re: Type SO as building wiring  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
He's also a financial idiot. SO cable is no bargain.


[Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#97824 - 03/31/06 11:49 PM Re: Type SO as building wiring  
SolarPowered  Offline
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Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Quote
He's also a financial idiot. SO cable is no bargain.


...Yet another example of the great lengths people will go to to do things wrong.


#97825 - 04/01/06 01:17 AM Re: Type SO as building wiring  
maintenanceguy  Offline
Member
Joined: Dec 2001
Posts: 300
Southern NJ, USA
While it sure seems like a bad idea and 400.8 seems to support what I believe. Except for two things:

1- Why is SO prohibited as a "flexible cord or cable" while NM, SE, or UF, which seem to be flexible as well, are not prohibited as building wiring?

AND

2- This is not a "substitute for the fixed wiring of a structure" since it will be the "fixed wiring of a structure". I'm not talking about an extension cord. He wanted to use SO in the same way that romex would be used.

I've been cited for 400.8 in lots of my buildings over the years for extension cords. I didn't think 400.8 applied to other than extension cords and drop cords.

edit: trying to get the ubb codes to work.

[This message has been edited by maintenanceguy (edited 04-01-2006).]


#97826 - 04/01/06 01:22 AM Re: Type SO as building wiring  
maintenanceguy  Offline
Member
Joined: Dec 2001
Posts: 300
Southern NJ, USA
I think I answered my own question. Found it in table 400-4.

Thanks everyone for the help.


#97827 - 04/01/06 07:53 AM Re: Type SO as building wiring  
winnie  Offline
Member
Joined: Sep 2003
Posts: 649
boston, ma
maintenanceguy,

As you noted, SO cord is one of the types of cord listed in article 400, not one of the wiring methods listed in the 300's.

However I see no reason that any given cord could not be multiply rated as both one of the types listed in article 400 as well as one or more of the methods listed in the 300s, in which case that cable assembly could be used for fixed wiring exactly as described.

I don't know if any such cables are actually manufactured, nor if there are specific requirements that make such a dual rating impossible, for example permissible wire stranding. I can imagine that there are situations where a single cable, dual rated as types TC and SO would be quite useful, essentially permitting permanently installed extension cords (with suitable protection and support, of course).

-Jon


#97828 - 04/01/06 12:37 PM Re: Type SO as building wiring  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Maintenanceguy, your question brings up a few basic things, that I feel I ought to explain for the benefit of everyone. You probably know most of this already, but this is for those who don't.....

First of all, while the NEC tries to be written in English, some times they wander, and use a term in a manner somewhat different than the rest of the world. It is also quite confused as to whether something not mentioned is allowed or forbidden.

"Flesible cords" in the NEC are limited to what is further defined in the code; you've seen the tables. Now, there are countless other items made that are both 'flexible,' and 'cords,' but they are not "flexible cords" as the code understands the term.
A prime example of this is the "festoon cable" you might see used on an overhead crane.


The other point is that UL, or anyone else, can only evaluate a product after having some idea as to its' intended use. As a result, they have various standards- one for Romex, one for UF, one for SO, etc. Strictly speaking, these are entirely different standards, and no one can say that something tested for one category is also appropriate for another category.

A great example of this is what happens when you bury S cable; it doesn't take very long for the rubber to rot away, leaving you with bare copper. UF cable buried for the same period will show almost no wear.

Another thing often overlooked in the use of SO cord is strain relief. There are different types made, varying in price from pennies to many dollars. Each is listed for use in certain circumstances, and a given method may not be adequate under all circumstances.


#97829 - 04/01/06 12:46 PM Re: Type SO as building wiring  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
"He wanted to use SO in the same way that romex would be used."

In a school, and/or above a drop ceiling, NM would be prohibited anyway.

I'd get someone else.

BTW,

Where in NJ are you?

[This message has been edited by Redsy (edited 04-01-2006).]


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