ROMEX IN PVC

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kwired

Electron manager
Location
NE Nebraska
Can I run 6/3 romex in pvc??
Other than for a short length of additional physical protection or a sleeve through masonry or some similar application, my question is why would you want to?

If you are using raceway wiring methods it cost less to pull individual conductors than to pull cables through.
 

j rae

Senior Member
Other than for a short length of additional physical protection or a sleeve through masonry or some similar application, my question is why would you want to?

If you are using raceway wiring methods it cost less to pull individual conductors than to pull cables through.
The price of #6THHN verses 6/3 romex is not much different and the conduit id big enough>
 

edward

Senior Member
Location
CA
Occupation
Electronologist
Other than mentioned by Kwired, why are you installing NM cable in PVC?
Is it for a hot tub that will go on the outside of the wall?
 

kwired

Electron manager
Location
NE Nebraska
The price of #6THHN verses 6/3 romex is not much different and the conduit id big enough>
NM cable is a 60C conductor.

If you are running a 50 amp circuit and you use THHN/THWN you can use 8 AWG. Just something to consider. Also you can often use as small as 10 AWG for the neutral.

I have started running more raceways in place of 6AWG NM cable than I used to. I get tired of buying large NM cable and having so many 10 to 20 foot pieces left over that are hard to find a use for. But I do use more 6 AWG for other applications and usually buy it on bigger quantity reels. I guess if I used more large sizes of NM cable more often I may look at this differently.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
No it cannot be in PVC if the conduit is in a wet location or damp locations. Yes, NM is allowed in PVC if the fill is observed and it is not in damp or wet location. You may also sleeve NM in PVC.
 

squaredan

Senior Member
Location
Pennsylvania
NM cable is a 60C conductor.

If you are running a 50 amp circuit and you use THHN/THWN you can use 8 AWG. Just something to consider. Also you can often use as small as 10 AWG for the neutral.
Would this not violate 110.14C1a (2008) ? I am guessing that the equipment that he is running power to would be 55amps or less.

Wouldn't he have to use the 60C column for equipment rated 100amps or less? I know he can use higher temp wire 110.14C1a2 but it would have to be from 60C column..Correct?

Dan
 
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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Dan, if the terminations are rated 75C as most are and the wire is rated at least 75C then you can use the 75C rating. The 60C rating for 100 amps or less is only if we don't know the termination rating of we know that the termination is 60C not 75C.
 

jap

Senior Member
NM cable is a 60C conductor.

If you are running a 50 amp circuit and you use THHN/THWN you can use 8 AWG. Just something to consider. Also you can often use as small as 10 AWG for the neutral.
Would this not violate 110.14C1a (2008) ? I am guessing that the equipment that he is running power to would be 55amps or less.

Wouldn't he have to use the 60C column for equipment rated 100amps or less? I know he can use higher temp wire 110.14C1a2 but it would have to be from 60C column..Correct?

Dan
You can use #8 Thhn/Thwn for a 50 circuit if you run conduit and pull individual conductors.
If you use Romex then you have to use the 60d C column and you'd have to pull #6 for a 50 amp Circuit.
I personally never reduce the Neutral Size but thats just me.
JAP.
 
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kwired

Electron manager
Location
NE Nebraska
I personally never reduce the Neutral Size but thats just me.
If the load is not there, then why?

Take a 50 amp circuit for a range, neutral load is likely less than 10 amps, maybe even less than 5 amps in most cases, but we must still have a neutral sized at least to 250.122. 10 AWG has plenty of capacity for the load it will see.
 
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squaredan

Senior Member
Location
Pennsylvania
Dan, if the terminations are rated 75C as most are and the wire is rated at least 75C then you can use the 75C rating. The 60C rating for 100 amps or less is only if we don't know the termination rating of we know that the termination is 60C not 75C.
yeah i was toying with that idea and I did read 110.14C1a3 also, but thought i give it go anyway..Thanks for the reply Dennis..

Dan
 

squaredan

Senior Member
Location
Pennsylvania
Hey Kwired that post of " I personally never reduce the Neutral Size but thats just me" was not by me even though it says my name.. I think i messed up the Quote in my post and somehow it just added my name..Sorry..
 

jap

Senior Member
If the load is not there, then why?

Take a 50 amp circuit for a range, neutral load is likely less than 10 amps, maybe even less than 5 amps in most cases, but we must still have a neutral sized at least to 250.122. 10 AWG has plenty of capacity for the load it will see.
I just never do.
Jap.
 

Rick Mack

Member
Location
Fort Mill, SC
-NEC 2011
- Use the Example of the 50 A Range circuit
- 250.122 sizes Equipment Grounding Conductors (EGC) not Grounded (neutral) conductors
- 210.19(A)(3)Ex.2 allows the neutral conductor for household cooking appliances to be smaller than the ungrounded conductors (70% of the branch circuit rating, but not less than 10 AWG, i.e.
.70 X 50A = 35A).

-If the 50A Range branch circuit is wired with individual conductors in conduit with THWN (75C) or
THHN (90C) insulation, then: 310.15(B)(16) Ungrounded conductors = 8 AWG, Neutral conductor = 10 AWG, Equipment Grounding Conductor (EGC) = 10 AWG (T250.122).

-If an SE cable with 75C insulation is used, then conductors sizes would be the same.
Note: NEC 2008 required SE used in Interior Installations to follow NM rules including 334.80 Ampacity, i.e. 60C column in T310.16. NEC 2011 excludes SE from 334.80 Ampacity requirements.

- If an NM cable is used then from 60C column: Ungrounded Conductors = 6 AWG, Neutral conductor = 8 AWG, and EGC is still = 10 AWG.
 

Rick Mack

Member
Location
Fort Mill, SC
I am getting used to posting here. I think I may have deleted the post I was trying to send. If this is a repeat post, I apologize.

- NEC 2011

-Reference the example of the 50A Range circuit

-T250.122 sizes the Equipment Grounding Conductor (EGC) not the Grounded (neutral) Cond.

-210.19(A)(3)Ex. 2 allows the neutral conductor for household cooking appliances to be smaller than the ungrounded conductors ( 70% of Branch Circuit rating, but not less than 10 AWG, i.e.
.70 X 50A = 35A).

- If a 50A Range branch circuit is wired in conduit with individual conductors with THWN (75C) or THHN (90C) insulation, then: 310.15(B)(16) Ungrounded Conductors = 8 AWG, Neutral conductor = 10 AWG, Equipment Grounding Conductor(EGC) = 10 AWG (T250.122)

-If an SE cable with 75C insulation is used, conductor sizes would be the same.
Note: NEC 2008 required SE used in Interior Installations to follow NM rules including 334.80 Ampacity (60C column in T310.16). NEC 2011 excludes SE from 334.80 Ampacity requirements.

- In an NM cable is used then from 60C column: Ungrounded Conductors = 6 AWG, Neutral Conductor = 8 AWG, and EGC is still = 10 AWG.
 

jap

Senior Member
I believe a NM 6/3 w/ground comes with a full size #6 Neutral not a #8.
And regardless of all the calculations I never pull a reduced neutral but thats just me.
 
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