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Discussion Starter · #1 · (Edited)
I have been curious as to how other electricians transition from indoor to outdoor wiring. Say for instance you want to install the wiring for a outdoor hot tub. You want the underground trench to have conduit. At first thought I figured you could run NMWU in the interior of the house then exit the house and continue the NMWU in the rest of the conduit. The problem with this is NMWU in not listed for installation in a conduit according to table 19 of the Ontario Electrical Code ( Probably the same for the Canadian Electrical code too). Another option is to install NMD90 in the interior of the house, install a junction box ( that will be assessable) that has a connection to the outdoor conduit, then splice the NMD90 to RW90. The RW90 would then continue to the hot tub. This would work and meet code but it seems impractical. What do you guys normally do?

By the way I remember asking my code instructor in college this and he was not to sure :laughing: :whistling2:
 

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I have been curious as to how other electricians transition from indoor to outdoor wiring. Say for instance you want to install the wiring for a outdoor hot tub. You want the underground trench to have conduit. At first thought I figured you could run NMWU in the interior of the house then exit the house and continue the NMWU in the rest of the conduit. The problem with this is NMWU in not listed for installation in a conduit according to table 19 of the Ontario Electrical Code ( Probably the same for the Canadian Electrical code too). Another option is to install NMD90 on the interior of the house, install a junction box that has a connection to the outdoor conduit, then splice the NMD90 to RW90. The RW90 would then continue to the hot tub. This would work and meet code but it seems impractical. What do you guys normally do?

By the way I remember asking my code instructor in college this and he was not to sure :laughing: :whistling2:
Too many acronyms for me.
 

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I have been curious as to how other electricians transition from indoor to outdoor wiring. Say for instance you want to install the wiring for a outdoor hot tub. You want the underground trench to have conduit. At first thought I figured you could run NMWU in the interior of the house then exit the house and continue the NMWU in the rest of the conduit. The problem with this is NMWU in not listed for installation in a conduit according to table 19 of the Ontario Electrical Code ( Probably the same for the Canadian Electrical code too). Another option is to install NMD90 in the interior of the house, install a junction box ( that will be assessable) that has a connection to the outdoor conduit, then splice the NMD90 to RW90. The RW90 would then continue to the hot tub. This would work and meet code but it seems impractical. What do you guys normally do?

By the way I remember asking my code instructor in college this and he was not to sure :laughing: :whistling2:
A lot of the hot tubs we wired with one of the companies I worked for, involved running NMD90 to the disconnect/breaker spa pack, then transitioned to Teck cable. Or if the spa pack wasn't mounted on the exterior wall of the house, it continued on to an appropriate location. Sometimes it transitioned from the spa pack to a whip. We never ran PVC conduit, but that may be in part to it being rather rocky here. It really depended on the situation of the spa pack.
 

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if it's accessible, then junction box inside and TW90 in conduit. If it's not accessible then NMD90 to an exterior junction box and either TECK or TW90 in conduit. Never been a big fan of NMWU for anything other than LV landscape lighting. MTCW
 

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Discussion Starter · #10 ·
It looks like its hard to get away from splicing the cable. I don't see why NMWU is not listed for installation in a conduit. The way I see it is if you are not exceeding conduit fill and have applied the correct ampacity you are good.
 

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I"ve never known exactly why you could or couldn't pull NMWU through PVC pipe, I've just never liked doing it as once it's in there, that pipe's pretty much done and it doesn't leave room for expansion (I'm all about leaving options open for down the road). And depending on the size of pipe, you can't pull it out if there's a problem.
I've certainly run across it often enough in the field and in all but one instance have had to abandon all of it.
 

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thanks frunkslammer

Pipe can only be used for mechanical protection, not as raceway conduit.
So below 1.5m it's mechanical protection and above 1.5m it's a raceway conduit?
If you can direct bury NMWU, why would pulling it through pipe for "added" mechanical protection be an issue.
Help me see the light on this one, please.

Even as an apprentice I never pulled NMWU through PVC pipe, but no one could tell me why, other than "don't do it", so I surmised it was due to space and the fact that RW or TW was cheaper and a hell of a lot easier
And now that I"m running around in the field fixing this, it's been nothing more than a waste of resources and time.

I'd love to be able to give clients a definitive answer.
 

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So below 1.5m it's mechanical protection and above 1.5m it's a raceway conduit?
If you can direct bury NMWU, why would pulling it through pipe for "added" mechanical protection be an issue.
Help me see the light on this one, please.

Even as an apprentice I never pulled NMWU through PVC pipe, but no one could tell me why, other than "don't do it", so I surmised it was due to space and the fact that RW or TW was cheaper and a hell of a lot easier
And now that I"m running around in the field fixing this, it's been nothing more than a waste of resources and time.

I'd love to be able to give clients a definitive answer.
pvc conduit does not readily transfer heat as easily as a metal conduit or raceway
so derating would be an issue.
 

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teck inside and outside, no need for junction box, teck is listed for almost any inside/outside conditions :laughing: and can be buried
is there a rule prohibiting teck inside a house
 

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Alberta here...

Talk to your inspection department. They may see things your way. After all that makes sense no?

I have run pvc 100% of the way and then pulled nmw through it, into the building to their point of attachments. No junction boxes, no changing of the wire types.

See if they will ignore the rule.

Edit: Some inspectors are picky and might not sign-off so you might also check with him/her. But if it's policy to turn a blind eye for the protection of the cable...

Myself I enjoy seeing lumps of dirt hit that pvc pipe when backfilling.
 

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If you can direct bury NMWU, why would pulling it through pipe for "added" mechanical protection be an issue.
Help me see the light on this one, please.

Even as an apprentice I never pulled NMWU through PVC pipe, but no one could tell me why, other than "don't do it", so I surmised it was due to space and the fact that RW or TW was cheaper and a hell of a lot easier
And now that I"m running around in the field fixing this, it's been nothing more than a waste of resources and time.

I'd love to be able to give clients a definitive answer.
Dude I JUST told you why you can't, because it's against Canadian Electrical Code.. many things in Canadian electrical can't be reasoned out, someone decided so and that's the law, unless you just want to break it.. I do sometimes.



You can see NMW(U) is not listed on there. But if you find where NMW(U) is listed.. it's:



So there, now you have an answer for clients.. tell them "I can not do that because it is against the conditions of use as permitted in Table 19 of the Canadian Electrical Code."
 
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