AHJ personal opinion

[Smart $]

ENT is over concrete slab. 2x4 laid on side. 3/4' Plywood sub floor on top and then 3/4" hard finish floor. Not wet area.

you may want to consider how deep these hardwood nails go through the subfloor because they generally do not only get nailed into the joists. It sounds like you are using 3/4" ENT which leaves less than 1/2" between the bottom of the subfloor and the top of the ENT (in a perfect world)

That's a good catch there Wenty4.

I would accept that as a valid reason for not useing the ENT. Physical protection may be needed.

Seems to me that 3/4" hard finish floor on top of 3/4" plywood subfloor (1-1/2" total) makes it compliant without any additional protection from physical damage.

 

[GoldDigger]

But with a T&G floor the head of the nail is below the top of the floor.

 

[Smart $]

But with a T&G floor the head of the nail is below the top of the floor.

Lacking detail to make an assessment.

The pertinent section is 300.4...

(D) Cables and Raceways Parallel to Framing Members
and Furring Strips. In both exposed and concealed
locations, where a cable- or raceway-type wiring method is
installed parallel to framing members, such as joists,
rafters, or studs, or is installed parallel to furring strips, the
cable or raceway shall be installed and supported so that the
nearest outside surface of the cable or raceway is not less
than 32 mm (11?4 in.) from the nearest edge of the framing
member or furring strips where nails or screws are likely to
penetrate. Where this distance cannot be maintained, the
cable or raceway shall be protected from penetration by
nails or screws by a steel plate, sleeve, or equivalent at least
1.6 mm (1?16 in.) thick.

Exception No. 1: Steel plates, sleeves, or the equivalent
shall not be required to protect rigid metal conduit, intermediate
metal conduit, rigid nonmetallic conduit, or electrical
metallic tubing.

Exception No. 2: For concealed work in finished buildings,
or finished panels for prefabricated buildings where
such supporting is impracticable, it shall be permissible to
fish the cables between access points.

Exception No. 3: A listed and marked steel plate less than
1.6 mm (1?16 in.) thick that provides equal or better protection
against nail or screw penetration shall be permitted.

 

[GoldDigger]

The quoted section refers to depth of framing members, not framing plus wall surface. I imagine a similar principle might apply to the floor situation.

 

[Smart $]

The quoted section refers to depth of framing members, not framing plus wall surface. I imagine a similar principle might apply to the floor situation.

It refers to joists... :huh:

A plywood subfloor can be considered a framing member, can it not?

How long are the nails used for 3/4" T&G hardwood flooring?

 

[iwire]

A plywood subfloor can be considered a framing member, can it not?

Not to me or anyone I know. It is sheathing.


But consider this, regardless of the floor depth if the wiring runs down the middle of this bay it is more than 1.25" from framing members.

 

[iwire]

The quoted section refers to depth of framing members,

The 1.25" applies in all directions.

If the wiring runs parallel to the framing members but is held at least 1.25" from the framing member the cable could rest against the back side of the sheathing.

 

[Smart $]

Not to me or anyone I know. It is sheathing.


But consider this, regardless of the floor depth if the wiring runs down the middle of this bay it is more than 1.25" from framing members.

I agree... just put it out there for consideration, good or bad.

But what really matters is the part about "...where nails or screws are likely to penetrate." Nailing down the plywood, they have a 3-1/2" margin of error. Then the flooring should generally be nailed on center above that except for joints that don't align with framing... and nailed on a ~45? angle. So how long are the flooring nails? Multiply by .707 and subtract 3/4" for plywood and 2/3 of 3/4" flooring. If 0" (or less ), flooring nails not likely to penetrate. Even slightly greater than 0", should we consider likely to penetrate the wall of the ENT or just the NM inside the ENT???

 

[Smart $]

...
But what really matters is the part about "...where nails or screws are likely to penetrate." Nailing down the plywood, they have a 3-1/2" margin of error. Then the flooring should generally be nailed on center above that except for joints that don't align with framing... and nailed on a ~45? angle. So how long are the flooring nails? Multiply by .707 and subtract 3/4" for plywood and 2/3 of 3/4" flooring. If 0" (or less ), flooring nails not likely to penetrate. Even slightly greater than 0", should we consider likely to penetrate the wall of the ENT or just the NM inside the ENT???

This should help...

http://www.powernail.com/home/depthchart.htm

 

[iwire]

But what really matters is the part about "...where nails or screws are likely to penetrate."

Really matter code wise or really matters in the real world?

Because in my opinion as soon as the wiring is 1.25" or greater from the framing member or furring strip that 'likely to penetrate' does not apply. .... Code wise.

The reality is flooring nails will likely penetrate at all locations.

 

[Smart $]

Really matter code wise or really matters in the real world?

Because in my opinion as soon as the wiring is 1.25" or greater from the framing member or furring strip that 'likely to penetrate' does not apply. .... Code wise.

The reality is flooring nails will likely penetrate at all locations.

Well Code leaves it open to interpretation, now doesn't it?

I agree where 1-1/4" or greater away from framing, but no matter which way the ENT/NM is run, it'll have to be secured. While to the slab is a possibility, what if to 2x4?

Flooring nails penetrating really depends on size/length used. According to depth chart on page I linked, 1-1/2" or less would not... and 1-3/4" only a 1/16". And don't forget the Code section wording can be interpreted as meaning penetrate the framing, not the sheathing... hmy:

 

[iwire]

Well Code leaves it open to interpretation, now doesn't it?

I don't believe it does.

I agree where 1-1/4" or greater away from framing, but no matter which way the ENT/NM is run, it'll have to be secured. While to the slab is a possibility, what if to 2x4?

If it has to be secured to the framing member it would be a good time to use a spacer type support. If not I see a lot of nail plates being used.

If it was cable these would work. http://www.erico.com/products/CADDYcfcCOJimCbleSpprt.asp

I don't know what I would use for smurf tube. I would probably use one hole clips and a ramset to fasten to the slab.

As far as nails, yes the length becomes an issue. It seems many carpenters use longer nails than needed or recommended.

 

[iwire]

And don't forget the Code section wording can be interpreted as meaning penetrate the framing, not the sheathing... hmy:

You lost me, the section talks about a distance away from a framing member. Not the length of nails or even what the nail might penetrate.

 

[Smart $]

I don't believe it does. ...

You lost me, the section talks about a distance away from a framing member. Not the length of nails or even what the nail might penetrate.

Well we'll have to disagree (not all that unusual ), but I'll quote the pertinent part again...

"... the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (1-1/4 in.) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate."

Seems to me it's saying where a nail or screw is likely to penetrate the framing member. You've already said the subfloor don't count as a framing member (and the requirement don't mention anything else, structural or finish.

With a 3-1/2" margin of error on nailing to the 2x4, I say a nail or screw is NOT likely to penetrate the framing member no matter what length is used to nail down the flooring or subflooring. Errantly-placed or overly-long nails or screws don't count toward a "likely" assessment. To do so would essentially eliminate the need to state "likely"... as everything is subject to an errantly-placed or an overly-long nail or screw penetrating it. :happyyes:

 

[mtfallsmikey]

What a thread... Which one of the Feasance brothers is the AHJ, Mal or Mis?

 

[kwired]

I agree... just put it out there for consideration, good or bad.

But what really matters is the part about "...where nails or screws are likely to penetrate." Nailing down the plywood, they have a 3-1/2" margin of error. Then the flooring should generally be nailed on center above that except for joints that don't align with framing... and nailed on a ~45? angle. So how long are the flooring nails? Multiply by .707 and subtract 3/4" for plywood and 2/3 of 3/4" flooring. If 0" (or less ), flooring nails not likely to penetrate. Even slightly greater than 0", should we consider likely to penetrate the wall of the ENT or just the NM inside the ENT???

Typical hardwood flooring is nailed pretty randomly and not at floor joists. In fact the nails used barely penetrate the underside of the subfloor so trying to hit the floor joists doesn't have any advantage, because you won't penetrate them enough to do any additional good.

 

[Smart $]

Typical hardwood flooring is nailed pretty randomly and not at floor joists. In fact the nails used barely penetrate the underside of the subfloor so trying to hit the floor joists doesn't have any advantage, because you won't penetrate them enough to do any additional good.

Have no experience with modern hardwood flooring. Of older hardwood flooring that I have had experience with, it had no subfloor... nailed right to the joists and joints were cut to either lap 1/2 the joist or spit the joist and a cleat. :happyyes:

Anyway, what you state follows what I was trying to point out... nails penetrating the subfloor is not part of the requirement.

 

[iwire]

Anyway, what you state follows what I was trying to point out... nails penetrating the subfloor is not part of the requirement.

True but regardless of that fact we agree on, the cables have to stay back 1.25" of the framing member edge that the sheathing attaches to.

If I tried telling an EI that the carpenters aim is so true that it is not likely they will miss the framing member when putting the sheathing down the EI would simply tell me that they do think its likely and that would be the end of the story.

 

[Smart $]

...the EI would simply tell me that they do think its likely and that would be the end of the story.

Sad, but true... even with a 3-1/2" margin of error... :thumbsdown:

 

[cowboyjwc]

What you are saying is that we could never leave ENT or PVC for use as a sleeve/chase to pull in cable at a later date. If we did we would be required to run a complete conduit system from box to box. This isn't metal and doesn't require bonding. NM has it's own sheath and isn't required to be in conduit and in this case is not used for physical protection.
All I have ever been required to do is use bell ends on the conduit. Putting a connector on each end will do it or even a coupling.

You could do this same install at a 100 different locations and only this one inspector is going to find fault with it and that's the problem.

If the ENT is not big enough and is overfilled the inspector should state that.

We fish NM through walls and never even get to see what all it's going through and this is allowed. So you don't think we should be allowed to fish through a nice clean conduit.

What exactly is the danger of this installation? The code is all about safety so what isn't safe.

Just because only one finds fault with something, doesn't mean that the other 99 are correct.