Is stranded wire inferior to solid core wire in this situation?

[MiniMe4Eng]

I have to run 2x20A and 1x15A circuits on the outside of the house for like 9m (27') -that is RW90 in conduit.

I have been trying without success to find solid core wire (individual wires) cut by meter. I would have to buy a 300m spool. Even if I use the same color for all the wires and use tape to mark the ground/neutral and hot I am still under 100m.

From what I am seeing it would be maybe easier to get stranded core.
My plan is to get with exterior rated cable to inside of the house and there to connect using a junction box with NMD cables which will be easier to push pull through the finished ceiling (there is insulation there)

From what the vendors told me this wire is more popular because it is easier to pull but from what I am reading technically it is less performant.

Are there any major problems that I should be aware of when using stranded wire ?

 

[waross]

I'm not a fan of PVC conduit. It gets brittle after a few years in sunlight and breaks.

Using PVC tubing as a conduit does not make it an electrical conduit and is not code compliant.
Approved electrical PVC conduit has an additive to make it UV (sunlight) resistant.
Please either stick to your area of expertise or take it to FaceBook.

 

[BN4537]

You could pull some UF cables in the conduit instead - it's like NM but rated for wet locations. Use 12 AWG copper wire for all three circuits and just buy a 100' roll of UF cable - you won't have a relevant amount of voltage drop in 27' and you can bundle up to 4 cable assemblies when they are 12/2, 12/3, 14/2, or 14/3 per NEC. The conduit is just to keep it neat and protect it from physical damage.

I wouldn't use NM cable for that application - it will likely work fine but is not intended for that environment. The individual wires are not actually THHN in an NM cable.

 

[BN4537]

Grounded conductor, #6AWG and smaller: NEC 200.6
Ungrounded conductors: NEC 235.5
Grounding conductor: NEC 250.119

There are code requirements for insulation colors, esp. for grounded conductors and grounding conductors in terms of continuous, colored insulation.

Mike

This is good. Some of the other responses are... somewhat misguided for house wiring, although they probably work fine in the industries that the posters are in.

If you can't find what you need locally, I have been pretty happy with ordering wire from Amazon. I still use the name brand stuff though, not interested in testing out unbranded or unpronounceable wiring.

My understanding is that the Canadian Electrical Code is similar to the NEC, I think the section numbers are pretty close.

 

[waross]

If this helps you I am in Ontario Canada

Wow. I started working part time wiring houses in 1956. Since then I have worked everywhere from wiring a log cabin in the Yukon Territory to helping to build Darlington Nuclear in Ontario.
You need a different supplier.
All colours in both solid and stranded and in sizes of #14, #12, #10 and others were easily available in Canada for over 60 years.
What changed?

 

[waross]

From what I am reading I have the option to buy a spool of 300M of white and mark it with colored tape

Find a friendly contractor who is willing to sell you short lengths.
Contractors will be buying 1000 Ft, 300M spools of all colours.

 

[TugboatEng]

Thank you for the clarification, mparenteau.

 

[waross]

you can bundle up to 4 cable assemblies when they are 12/2, 12/3, 14/2, or 14/3
per NEC.

Ontario is under the CEC, not the NEC.
I had to go in and clean up someone else's deficiencies under the CEC.
One of the code fails was cable bundles of "12/2, 12/3, 14/2, or 14/3"

You could pull some UF cables

Is UF a new designation for building wire?
Is it approved for use as a building wire?

 

[waross]

Is it approved for use as a building wire?

I don't believe that UF is approved for Canada.

 

[TugboatEng]

MTW?

 

[waross]

MTW?

Machine Tool Wire?
Not approved as a building wire.
Probably ok on a scow.

 

[BN4537]

Is UF a new designation for building wire?
Is it approved for use as a building wire?

This is basically the Canadian version of UF - https://www.homedepot.ca/product/southwire-12-3-nmwu-30m-underground-copper-wire-black/1000534710
Be aware, it looks like it's only rated to 60 degrees C, so the ampacity adjustments will be different than NM cable.

One of the code fails was cable bundles of "12/2, 12/3, 14/2, or 14/3"

You guys don't have the ampacity adjustment of 70% for 8 conductors? How many NM can you bundle without an ampacity adjustment that drops the breaker size?

 

[waross]

1 to 3 current carrying conductors without derating.
For a bundle of Romex, count the current carrying conductors. The neutral counts in 2 conductor Romex.

 

[waross]

Too many people are posting outside their area of expertise.
Remember;
"A know it all is particularly annoying to those of us who actually do know it all." grin.
Someone's tag line;
"FaceBook may have never caused to lame to walk but it has certainly caused the dumb to speak."
Generally on this site there is a trend towards advice that would be more appropriate on FaceBook.

 

[BN4537]

1 to 3 current carrying conductors without derating.
For a bundle of Romex, count the current carrying conductors. The neutral counts in 2 conductor Romex.

Right, but doesn't 12 gauge wire still work on a 20 amp breaker at 70% derate? You start with 90 degree C wiring ampacity, reduce ampacity to 70 percent, and it still works as 60 degree C wiring on a 20 amp breaker? Or do you guys have to start at 60 degrees and then derate?

NEC we are allowed to start at 90C by 334.80, and as long as the number you come up with works for 60C, you would be ok. That math comes out to four cables in 12/2, 12/3, 14/2, or 14/3, since the neutral doesn't count in the 3 wire cables.

 

[waross]

I am not going to waste any more time discussing the ratings of an inappropriate cable.
Take it to FaceBook.

 

[TugboatEng]

Waross, a forum isn't a place for experts to validate each other. That would be pointless. It's a place for people to say things, sometimes incorrect, and get corrected. This thread has a lot of that going on and that's a good thing.

 

[LionelHutz]

Isn't Romex type wire solid? Doesn't that get pulled in conduit? If individual wires are wanted there are jacket strippers and it is available in short lengths.

You need to stick to commenting about what you know. Stripping and using the romex conductors in conduit is NOT allowed by the electrical code.

Almost EVERY industrial or commercial site in North America is using stranded wires pulled through conduit. It's installed Everywhere there is conduit. And funny enough it's not failing all the time. Imagine that, it works as intended when installed correctly. So, again you need to stick to commenting about what you know and quit posting uninformed comments.

AWG 14, and AWG 12, solid wire.
AWG 10, solid or stranded.

I've been around electrical installation and electricians doing it for over 30 years and have never seen solid being installed or met an electrician who would install solid. You can get THHN in both stranded and solid, the stranded does pull around bends easier.

 

[MiniMe4Eng]

If I give up the optional circuit I think I can do this

• 3 hot wires (1 per circuit)
• 3 neutral wires (assuming no shared neutrals)
• 1 common ground

Total wires = 7 conductors

Conduit Fill (CEC Table D4)​

1" Schedule 40 PVC supports:

• 10 x #12 RW90
• 8 x #10 RW90

You are using 7 wires — well within the conduit fill limit for either size.

Derating (CEC Table 5A)​

You're running 6 current-carrying conductors (3 hots + 3 neutrals):

Wire Size	Base Ampacity (90°C RW90)	80% Derating	Result
#12	25A	20A	OK for 15A & 20A breakers
#10	30A	24A	OK for 20A+

So:

• You can use #12 RW90 for the 15A circuits
• You can use #12 RW90 for the 20A circuit, as it’s still good for 20A after derating
• Use #10 RW90 for ground (common, over-sized)

Code Notes​

• RW90 stranded is allowed for outdoor conduit use
• Common ground is fine — just must be sized to largest required (CEC Table 16, typically #10 for 15A/20A circuits)
• No derating applied to the ground wire

Recommended Wiring Breakdown​

Circuit	Breaker	Wire Size	Hot	Neutral	Ground
Hair dryer	15A	#12 RW90	1	1	Common #10
Smart toilet	15A	#12 RW90	1	1	—
Kitchen	20A	#12 RW90	1	1	—

✔ All in same 1" PVC
✔ 6 current-carrying conductors
✔ 1 ground
So all the cables 12/1 stranded and 2x20A breakers and 1x15 breakers (already acquired 2x15 and 2x20)

 

[LionelHutz]

You start with 90 degree C wiring ampacity

Where is this being applied? The terminations are 75C rated so you can't use 90C ratings for the wires where they terminate.

 

[LionelHutz]

This is just running outside and back into the same building, right?