Old 2-wire NM listed for covering with insulation?

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Electron_Sam78

Electron_Sam78

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Palm Bay, FL
Does anyone know if the old, 2-wire, cloth covered NMC can be covered with insulation. I've seen it in both insulated and non insulated attics but the question actually came up and I don't know the answer.
 
Electron_Sam78 said:
Does anyone know if the old, 2-wire, cloth covered NMC can be covered with insulation. I've seen it in both insulated and non insulated attics but the question actually came up and I don't know the answer.
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Do you really mean "NMC"?

If you meant "NM" the answer is yes. Old NM could be installed in direct contact with thermal insulation.
 
Electron_Sam78 said:
Yes NM, didn't mean to put NMC. Thanks for the input. Do you have any source citation for that?
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Rather than list the NECs published from the mid Twenties, please describe the physical installation you are asking about. What is its year of original installation?
 
That's just like the house that I grew up in, in eastern Nebraska. Ten below in the winter and a hundred and five in the summer. Silver painted bituminous compound impregnated cloth and paper sheath, old thermoset plastic or rubber insulation (depending upon the stock that the supplier had), and no equipment grounding conductor at all.

The 1953 NEC Article 336 Non Metallic Sheathed Cable is silent about thermal insulation. This is not unusual.

Even Knob & Tube was legal to be covered in thermal insulation until that was prohibited by quotable rule in the mid Eighties.

So, the answer is: The NEC does not prohibit the installation of NM in thermal insulation.
 
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