Type NM in EMT

[scotteng]

Can Type NM cable be installed in EMT in dry locations in a single family dwelling? This is not a question of whether or not it's a good practice, but one of code allowance.

 

[Dennis Alwon]

Yes it is compliant as long as you are aware of the fill or any de-rating that may be needed

 

[AC\DC]

Yes

 

[AC\DC]

Dang it

 

[Dennis Alwon]

Dang it

You want to go first--I'll delete my response...lol

 

[infinity]

Can Type NM cable be installed in EMT in dry locations in a single family dwelling? This is not a question of whether or not it's a good practice, but one of code allowance.

Yes it's allowed. For flat cables you would need to size the EMT as if the cable were round using its largest dimension. Since it's considered a single conductor you can use 53% fill of the raceway.

 

[Dennis Alwon]

Note 9 to the tables in Chapter 9-- to expand on what Infinity stated

A multiconductor cable, optical fiber cable, or flexible
cord of two or more conductors shall be treated as a
single conductor for calculating percentage conduit or
tubing fill area. For cables that have elliptical cross
sections, the cross-sectional area calculation shall be
based on using the major diameter of the ellipse as a
circle diameter. Assemblies of single insulated conductors
without an overall covering shall not be considered
a cable when determining conduit or tubing fill area.
The conduit or tubing fill for the assemblies shall be
calculated based upon the individual conductors.

 

[tom baker]

This is often done in basement for a receptacle onexposed wall, use EMT on the wall up to ceiling

 

[electrofelon]

Yes it's allowed. For flat cables you would need to size the EMT as if the cable were round using its largest dimension. Since it's considered a single conductor you can use 53% fill of the raceway.

So what size does that equal for 12-2? Will it fit in half? (Too lazy to do the math and looking up)

 

[infinity]

So what size does that equal for 12-2? Will it fit in half? (Too lazy to do the math and looking up)

53% of 1/2" EMT is 0.161 square inches. I don't have the width of 12/2 at the moment.

 

[electrofelon]

53% of 1/2" EMT is 0.161 square inches. I don't have the width of 12/2 at the moment.

Ok I don't have calipers, but using my tape measure looks like about 6 and a third 16's or .395. so an area of .122. looks like it fits!

 

[wwhitney]

Southwire says their 12/2 NM has a width of 0.430". Click on the "specifications" tab on this page:

12-2 CU NM-B WITH GROUND 250 FT | Southwire

Need a reliable cable for your residential wiring? Choose Southwire's 12-2 CU NM-B with ground 250 FT cable, designed for easy installation.

www.southwire.com

That's an area of 0.145 in².

Cheers, Wayne

 

[electrofelon]

Southwire says their 12/2 NM has a width of 0.430". Click on the "specifications" tab on this page:

12-2 CU NM-B WITH GROUND 250 FT | Southwire

Need a reliable cable for your residential wiring? Choose Southwire's 12-2 CU NM-B with ground 250 FT cable, designed for easy installation.

www.southwire.com

That's an area of 0.145 in².

Cheers, Wayne

The stuff I measured was definitely smaller than that. Perhaps a different brand or manufacturing differences , but irregardless it still fits in 1/2 EMT

 

[Tulsa Electrician]

See if this helps
From one of my books

 

[micabay]

This is often done in basement for a receptacle onexposed wall, use EMT on the wall up to ceiling

Tom,
Thanks for this real world application. I have seen this a number of times in older basements. Yet wondered if this was kosher or not. Not many basement in these new developments popping up all over Kitsap.
Drew

 

[tom baker]

Tom,
Thanks for this real world application. I have seen this a number of times in older basements. Yet wondered if this was kosher or not. Not many basement in these new developments popping up all over Kitsap.
Drew

You’ll need a bushing on the end of EMT, there is a push on plastic one, I use a box connector

 

[Fred B]

You’ll need a bushing on the end of EMT, there is a push on plastic one, I use a box connector

I Will usually have one of these couplers on the EMT where the NM is going into the EMT not a bushing.

Another note is that the NM sheathing is not to be stripped as it runs through the conduit. (Just thought I'd point it out as other posts had asked can this be done.)

 

[goldstar]

I Will usually have one of these couplers on the EMT where the NM is going into the EMT not a bushing.
View attachment 2558681
Another note is that the NM sheathing is not to be stripped as it runs through the conduit. (Just thought I'd point it out as other posts had asked can this be done.)

That's the connector that most EI's in my area will accept. Is there a Code section that doesn't allow you to strip the sheathing off the NM cable ? What happens if you have one cable in and one cable out to another receptacle ?

 

[electrofelon]

That's the connector that most EI's in my area will accept. Is there a Code section that doesn't allow you to strip the sheathing off the NM cable ? What happens if you have one cable in and one cable out to another receptacle ?

I would say two issues with stripping. First is the article 310 marking requirements, but more importantly the NM inners are not an approved article 310 conductor.

 

[Dennis Alwon]

I would say two issues with stripping. First is the article 310 marking requirements, but more importantly the NM inners are not an approved article 310 conductor.

I believe they are approved but aren't labeled or marked. There is a difference IMO