Where does code still alllow use of NM (NO -b)?

[junkhound]

Have other uses if not code compliant, just wondering and one of the code gurus will know without me searching. <G>

 

[don_resqcapt19]

334.112 requires that the NM being installed have conductor insulation rated at 90°C. That is what the "-B"indicates, so there is no provision in current codes to use other than NM-B.

 

[norcal]

If you have rolls of NM cable sitting around, it's scrap metal for the reason mentioned above.

 

[infinity]

If you have rolls of NM cable sitting around, it's scrap metal for the reason mentioned above.

Which is kind of strange since you can only use it at it's 60° C ampacity anyway.

 

[augie47]

Which is kind of strange since you can only use it at it's 60° C ampacity anyway.

At one time it made decent sense to me having dealt with "baked" wiring in ceiling boxes before NM-B was required and folks put 150 watt incandescent lamps in ceiling fixtures. With LED lamps now the prevelant lighting, that problem is not likely to occur.

 

[mopowr steve]

At one time it made decent sense to me having dealt with "baked" wiring in ceiling boxes before NM-B was required and folks put 150 watt incandescent lamps in ceiling fixtures. With LED lamps now the prevelant lighting, that problem is not likely to occur.

Agree,
Most lighting fixtures call for a wiring method that contains 90* conductors for terminations, hence why NM-B is the wire required to meet that spec.
That’s due to all those baked connections/wire inside the fixture boxes that were exposed to the heat generated by fixtures. Especially the flush surface type.

 

[ptonsparky]

Nothing like 300 watt lamps in totally enclosed fixtures with insulation added above later, to test that 60 degree.

 

[Speedskater]

When was the last 'NM' manufactured or sold in the US?

 

[mopowr steve]

When was the last 'NM' manufactured or sold in the US?

IMO, I would say around the mid 80’s