Crawlspace Wall Dilemma

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JohnE

Senior Member
Location
Milford, MA
In MA a basement is defined in in 502.0 as "that portion of a building which is partly or completely below grade".

Then, 3603.8.1 says "unfinished basement is required to have minimum clear ceiling height of six foot eight inches, except under beams, girders, ducts or other obstructions where the clear height shall be a minimum of six feet four inches."

Cralwspace is not defined, but it seems clear to me that any basement with ceiling lower than 6'8" is a crawlspace.

Crawlspaces are differentiated from basements in a number of areas of the building code.

MA building code is based on the old BOCA code, but there are many similarities between it and IRC or IBC. I can check these books at home later.

John
 

dlhoule

Senior Member
Location
Michigan
j_erickson said:
In MA a basement is defined in in 502.0 as "that portion of a building which is partly or completely below grade".

Then, 3603.8.1 says "unfinished basement is required to have minimum clear ceiling height of six foot eight inches, except under beams, girders, ducts or other obstructions where the clear height shall be a minimum of six feet four inches."

Cralwspace is not defined, but it seems clear to me that any basement with ceiling lower than 6'8" is a crawlspace.

Crawlspaces are differentiated from basements in a number of areas of the building code.

MA building code is based on the old BOCA code, but there are many similarities between it and IRC or IBC. I can check these books at home later.

John

John, I agree with you, most places have a basement defined in some manner. We have been discussing the NEC which: as far as I can tell does not cover NM in crawl spaces and so there is no approved method of installing NM in a crawl space unless you classify a crawlspace as not having any exposed wiring. In which case it won't matter how you run the NM, because it is not exposed. To me that is a stretch in most cases.
 

eprice

Senior Member
Location
Utah
Maybe I've missed it somewhere in all of these posts on this thread, but I can't find anything in the code that would relieve NM in attics from the same requirements that apply to crawl spaces. 334.15 applies to exposed work. Article 100 defines Exposed (as applied to wiring methods) as "On or attached to the surface or behind panels designed to allow access". The building code requires access to both the crawl space and the attic. The definition of exposed seems to apply equally to each.

iwire said:
334.23 is another specific code section allowing NM to be used in attics per 320.23.

No, I don't think so.

334.23 In accessible Attics. The installation of cable in accessible attics or roof spaces shall also comply with 320.23

Because of the word "also", 334.23 does not remove the requirement that NM in attics comply with 334.15. It merely adds the additional requirements found in 320.23.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I've been out and about, just catching up again. :)

j_erickson said:
OK, this thread is kind of long, so can someone explain the substantiation for being able to staple nm to the bottom of joists.
georgestolz said:
This leaves two arguments, as I see it:

  • Are they exposed or not exposed?
  • If they are exposed, are the joists the building finish?
I had decided (I don't think anyone ran with the idea) that attics are not exposed work, in this post. They are covered outside of 334.15, the exposed work section.

eprice said:
Article 100 defines Exposed (as applied to wiring methods) as "On or attached to the surface or behind panels designed to allow access". The building code requires access to both the crawl space and the attic. The definition of exposed seems to apply equally to each.
That's an excellent point. But I would counter that my above argument still holds water (that attics are not "exposed") due to the fact that they are dealt with seperately than all other ostensibly exposed spaces, and no reference is made in 320.23 to 334.15(A).
eprice said:
Because of the word "also", 334.23 does not remove the requirement that NM in attics comply with 334.15. It merely adds the additional requirements found in 320.23.
That's a devastatingly good point. My only (feeble) counter would be that such an interpretation is taking for granted what the original item was that is being added to.

You're seeing it as: In addition to the requirements already upon it by 334.15(A), you will also comply with 320.23.

But it could (very easily) be: In addition to this Article, the installation shall also comply with 320.23. In that case, there is nothing singled out to marry this up to. There is no more reason to suspect that an attic is any more a 334.15(A) installation than an unfinished basement is.

j_erikson said:
Earlier, I thought the argument was whether you could install nm cables through bored holes in a crawlspace...
That was more of a sidebar - we came to the realization that 334.15(A) did not leave provisions for holes in joists. Speaking for myself, I regarded it more as a mistake than an intentional omission.

j_erickson said:
I can't see any prohibition from using romex in a crawlspace unless it's considered a damp location.
Agreed. This discussion is more of the how it's legally installed than whether it can be legally installed.

Edit: I forgot Larry from Michigan was working that angle. Sorry for the brainfart.
 
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electric_instructor

Senior Member
To the best of my knowledge, all ANY NM cable requires is a 1 1/4" space to protect it from staples/nails, whether in a wall, attic, or floor?

The 1 1/4" is the "maximum" that I'm aware of, without requiring a metal plate, to be used for protection?

If easily accomplished I would drill holes, if NOT, then I would consider "stand-off" strips.

Therefore, I would consider this when choosing any "strips" or "angeled" braces for protection.

To the best of MY knowledge, all that is "required" is a 1 & 1/4 inch spacing to protect the wire from any intrustion by nails, and screws, even in the WORST of conditions?
 

electric_instructor

Senior Member
Sorry, BUT to reduce it to MAX simplicity, the CODE is only a MINIMUM saftey standard.

When looked at OVERALL, the code only requires a 1 & 1/4" saftey margin, in ANY location, whether in bored holes, or otherwise?

If inside a wall, or in an attic, or under a floor, the clearances are very specific.

We seem to be worried about the protection of the NM cable from below. What about from above? From the flooring, and possable damage from above?

We are given DEFFINATE measurments for protecting the cable, whether from below, OR above, OR from the sides.

Everyone talks about usage of the "crawlspace" by occupants, what about the use of said space by plumbers, HVAC contractors, or telephone, CATV etc? What of an insulation contractor, who is called upon to insulate a home floor?

I believe that the CODE, tries to foresee the possability that a plumber just MIGHT run a sewer line, at a later date, and that line MAY, need to reside against the bottom of several joists, reguardless of "occupancy", or owner "access". Surf boards are but ONE of MANY possable obstuctions.

Future insulation is ONLY one of many possabilities.

We, electricians are NEVER alone in the living world.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
To the best of MY knowledge, all that is "required" is a 1 & 1/4 inch spacing to protect the wire from any intrustion by nails, and screws, even in the WORST of conditions?


This only applies to framing members and furring strips where nail or screw penetration is likely. In George's scenario a running board with the cables attached to it would not require the 1 1/4" dimension in any direction.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
infinity said:
This only applies to framing members and furring strips where nail or screw penetration is likely. In George's scenario a running board with the cables attached to it would not require the 1 1/4" dimension in any direction.
Agreed - the damage possible in an unfinished basement is not the same as the 1.25" requirements laid down in 300.4. :)
 
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