From: clewis@ferret.ocunix.on.ca (Chris Lewis)
Newsgroups: rec.woodworking
Subject: Re: Exposed wiring and the NEC.
Date: 15 Aug 92 04:04:25 GMT
Organization: Elegant Communications Inc., Ottawa, Canada

In article <1992Aug14.222736.28498@philabs.philips.com> mja@philabs.philips.com (Michael Amato) writes:

>I am in the process of installing outlets and switch boxes in my 
>new garage (basement level, block walls) and I have a question
>reguarding exposed wiring. I was planning on running the horizontal
>portions through the ceiling (floor joists) and dropping down for
>each plug/switch using romex tacked to wood furing strips attached to
>the wall. The boxes would be surface mounted 4' off the floor (other
>wiring details deleted). From what I was able to get from the NEC,
>exposed wiring only needs to be protected from damage (ie. put in
>thin wall) when coming up through the floor (or near the floor) for
>about 18" or so. Now when I read this groups Electrical Wiring FAQ 
>(yes, some poeple do read it before posting)

Yeah! ;-)

> it states:

>	Romex is a brand name for a type of plastic insulated wire.
>	Sometimes called non-metallic sheath.  The formal name is NM
>	(NEC) or NMD90 (CEC).  This is suitable for use in dry,
>	protected areas (ie: inside stud walls, on the sides of joists
>	etc.), that are not subject to mechanical damage or excessive
>	heat.  Most newer homes are wired almost exclusively with NM/NMD90.
>	
>	Where the wire is subject to damage (ie: closer than 1 1/4" of
>	the face of the stud, on the surface of walls below 5 feet, on
>                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>Could someone tell me where to find this in the code?

This is what is in the CEC:

	12-518 Protection for Cable in Exposed Installations.  Cable
	       used in exposed wiring shall be adequately protected
	       against mechanical damage where it passes through a
	       floor, is less than 1.5m above a floor, or where exposed
	       to mechanical damage.

1.5m is 5 feet.  This usually manifests itself in things like short pieces
of flexible conduit on supply cables for furnaces or water heaters when
they "hop" from the wall to the appliance.

In one of the wiring jobs we did, we had similar questions of our inspector.
He wanted to see the wiring protected where it is possible for it to be
struck by a car.  Which in our case was something like 3 1/2 or 4 feet.
He wanted full blown rigid conduit, not thinwall or EMT or PVC.

[The wires were to enter a masonry wall garage at about floor level, and then
go straight up to 5 feet to supply several outlets.  The solution was
an "L" of rigid conduit.  The foot going thru the wall, the upper part
up the wall's surface.]

Of *course* the quote is from the CEC (Canada) instead of the NEC (USA).
If someone can provide me with a short quote from the NEC similar to the
above that mandates a different height, I will adjust the FAQ to indicate
the difference.

Steven and I did chat about this, but I'm unsure of whether he searched
for something or not.

However, given the difference between code and practise that we encountered,
the only guaranteed way to tell is to ask the inspector what he'll accept.
-- 
Chris Lewis; clewis@ferret.ocunix.on.ca; Phone: Canada 613 832-0541
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