I got a flushmount ceiling light that has a 90C wiring warning on it.

My home was built in 1956. I found the electrical wiring that runs to the light I want to change. I can't read the text printed on the wiring completely, it partially reads:


Here's a picture of the fixture on the other side:

enter image description here

Anyone know if "NM-B" wiring is safe for 90C?


  • 1
    In this day and age there is no earthly reason for a new residential luminaire to rise to 90C. That much heat is only made by incandescents (quite obsolete) or high-intensity discharge lights (decently efficient, but far too bright for residential, and obsolete too). – Harper - Reinstate Monica Mar 17 '17 at 15:28

NM-B is rated for 90°C. Here's an excerpt from Southwire’s Romex® SIMpull® Type NM-B web page.

Southwire’s Romex® SIMpull® Type NM-B (non-metallic sheathed cable) may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90°C...

From NEC

National Electrical Code 2017

Chapter 3 Wiring Methods and Materials

Article 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS

334.112 Insulation. ...Conductor insulation shall be rated at 90°C (194°F).

However, keep in mind that the ampacity is limited to that of a 60°C conductor.

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