What is the difference between NM and NMB romex cable? Code here now will
not allow NM to be used. WW

WW wrote:
What is the difference between NM and NMB romex cable? Code here now will
not allow NM to be used. WW

Plain NM w/o any following designation is the old, original "Romex (tm)"
that used fiber insulation and hence was dry-only application. NM-C
followed w/ the plastic. NM is, for the most part, unavailable.

AFAIK, the "B" designation is for building application and is the
nomenclature for the color-coded sheathing of white/yellow/etc. designed
to aid in ensuring proper conductor size is used in appropriate circuits
and making for easier/quicker verification during inspection.

--

"WW" wrote in message
news
What is the difference between NM and NMB romex cable? Code here now will
not allow NM to be used. WW
The difference is the temperature rating of the conductors in the cable. I
believe that NM used type "T" conductors rated at 60 degrees, and NMB uses
type "THHN" rated at 90 degrees

On 06/20/2010 10:31 AM, dpb wrote:
WW wrote:
What is the difference between NM and NMB romex cable? Code here now
will not allow NM to be used. WW

Plain NM w/o any following designation is the old, original "Romex (tm)"
that used fiber insulation and hence was dry-only application. NM-C
followed w/ the plastic. NM is, for the most part, unavailable.

AFAIK, the "B" designation is for building application and is the
nomenclature for the color-coded sheathing of white/yellow/etc. designed
to aid in ensuring proper conductor size is used in appropriate circuits
and making for easier/quicker verification during inspection.

--

I'm pretty sure the main diff between NM and NM-B is the higher temp
rating of the insulation used. 90C vs. 60C IIRC. (remember back in the
day taking down light fixtures and having to keep heat shrink handy to
cover up the wire ends where they crumbled when you flexed them?)

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

"dpb" wrote in message
...
WW wrote:
What is the difference between NM and NMB romex cable? Code here now will
not allow NM to be used. WW

Plain NM w/o any following designation is the old, original "Romex (tm)"
that used fiber insulation and hence was dry-only application. NM-C
followed w/ the plastic. NM is, for the most part, unavailable.

AFAIK, the "B" designation is for building application and is the
nomenclature for the color-coded sheathing of white/yellow/etc. designed
to aid in ensuring proper conductor size is used in appropriate circuits
and making for easier/quicker verification during inspection.



--Type NM was manufactured into the 80's and had thermoplastic covering,
and came in a variety of colors like white, black, and blue. Type NMC, and
NMS are non metallic cables with different properties, for other purposes.

"WW" wrote in message
news
What is the difference between NM and NMB romex cable? Code here now will
not allow NM to be used. WW
Thank you for the replies, now I have been educated. Very helpful group. WW