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Install NMWU in underground pvc conduit?
I've always thought it was against code but cant for the life of me find where it says we can't in the code book. My buddy says its fine. Basically I have a friend who wants to install 6/3 NMWU in a 1-1/4" pvc conduit to a hot tub.
Now I'm pretty sure he needs 90 degree wire and I've never come across 6/3 NMWU90 cable.
Any thoughts?
Thanks
 

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There is no cable rated to be installed in a conduit. A protective sleeve is allowed, but it cannot be a continuous run. Straight runs allowed only. The ratings of cables/wires is in Table 19.

However,

There has been a change to the 2012 CEC

12-902 Types of conductors and cables (see Appendix B)
(1) Conductors and cables shall be of types suitable for use in raceways as indicated in Table 19.
(2) Notwithstanding Subrule (1), armoured cables as described in Rule 12-602(6) shall be permitted to be
installed in a conduit or tubing provided that
(a) the installation will not result in a greater fill than that specified in Table 8; and
(b) the installation conforms to one of the following conditions:
(i) the length of cable pulled into the conduit or tubing does not result in the calculated maximum
pulling tension or the calculated maximum sidewall bearing pressure being exceeded; or
(ii) the run of conduit or tubing between draw-in points does not have more than the equivalent
of two 90° bends with minimum radii of not less than 0.944 m for cable rated 1000 V or less
and 1.524 m for cable rated in excess of1000 V, and is limited to a maximum of
(A) 15 m for a three-conductor copper cable;
(B) 45 m for a single-conductor copper cable;
(C) 35 m for a three-conductor aluminum cable; or
(D) 100 m for a single-conductor aluminum cable.
 

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There is no cable rated to be installed in a conduit. A protective sleeve is allowed, but it cannot be a continuous run. Straight runs allowed only. The ratings of cables/wires is in Table 19.
I've always run a pvc conduit, 90 up, LB in to both buildings, NMW in. Then free-wire it to the panel at one end and the light switch or whatever at the other end. This would be to a garage or a pole light or a GFI recpt. Trench at 18 inches. The trench is rarely straight.

Always. I'm pretty sure I've never run NMW direct burial. Always with conduit to protect it.

Just reading that rule makes me :blink:. I'm thinking the mayor of Toronto is sitting in on the code board. However I'm sure they have their reasons. Also people much smarter than me such as engineers, scientists, etc. coming up with the lengths, number of bends, bending radii, and of course all related to the number and type of conductor.

^^
I wonder the cost of that rule. No wonder we pay +$175.00 for the code book. Someone was telling me we should just use the NEC and dump the Committee on the CEC. There must be a thousand or so all flying about the country having a good time, good food on our dime.

Edit:

Now why the NMW surrounded by filthy dirt is better/safer than installed in a nice clean, reusable conduit, surrounded by filthy dirt, rocks, etc. is... well I suppose the code rules eh?

I've not had a problem with the inspection department on my installs?
 

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Edit:

Now why the NMW surrounded by filthy dirt is better/safer than installed in a nice clean, reusable conduit, surrounded by filthy dirt, rocks, etc. is... well I suppose the code rules eh?

I've not had a problem with the inspection department on my installs?
The reason that was explained to me was that it is possible to damage the insulation or conductors, as they are being pulled by their insulations, not the conductors, and have not been listed to be pulled in such a way.

I know of many inspectors that would agree with you, and ignore that rule. Can't say as I blame them, some rules make less sense than others. I think the intent is sound, and I would personally allow other cables pulled in the same manner.
 

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that rule finally makes some sense to me now, obviously most homeowner pulls are simple runs and no damage would happen, but imagine a long underground pull stuffed to capacity with a few nmwu cables, with a couple bends, you could easily pull so hard and take the insulation right off. seems to me code rules are based in worst case scenario not common best case. just because something has a 99.9% chance of not happening doesn't mean it's safe. I'm sure nothing serious would come from pulling the jacket off in a PVC pipe underground, I mean I don't even see anything bad happening running t90 underground outside instead of rw90, but rules are rules. what is worst case for unrated conductors in pipe in wet location? water infiltration destroys the insulation over time leading to a short, to a broken breaker that leads to a house fire? it's a stretch but I think that is the thought process when they write these things.
 

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Install NMWU in underground pvc conduit?
I've always thought it was against code but cant for the life of me find where it says we can't in the code book. My buddy says its fine. Basically I have a friend who wants to install 6/3 NMWU in a 1-1/4" pvc conduit to a hot tub.
Now I'm pretty sure he needs 90 degree wire and I've never come across 6/3 NMWU90 cable.
Any thoughts?
Thanks
Wouldn't it be more economical to pull TW90 or RW90 in the conduit, not to mention easier to pull? Mind you TECK90 has come down in price significantly, just DB that instead.

I just ran across a nightmare where the previous homeowner of a friends house had pulled 14/2 NMWU though 1/2' PVC, but the start of the run was from an external WP PVC box that had the back drilled out to feed into a potting shed. The back wasn't sealed by any stretch of the imagination so water eventually filled the PVC run and the freeze/thaw cycle broke the pipe and settling caused the pipe to sever the NMWU, it's been subsequently abandoned.
 
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