ROMEX ????? Have we been doing it wrong

[rgiraldo]

What is the attic temp in the summer? 86f deg 100f deg or 140f deg.

Now NM cable is rated at 60c right. Now read article 334.80 I find this funny. If you get it then post your thoughts.

Now look at the correction Factor, if the wires are tested at 86 F per 310.16 and if your attic does not reach over 131F you will be ok with NM cable. Correct right

Now what the real temp in a florida attic.


oh don't forget to derate

 

[don_resqcapt19]

The derating for NM starts with the 90?C ampacities. The OCPD is limited to the 60?C ampacity.

 

[bphgravity]

The issue of ambient temperature in an attic space really isn't limited to Florida. Most if not all states will see maximum temperatures above 86 degress F in attic spaces, especially as the codes continue to call for tighter construction and more energy efficient construction. Keep in mind the 86 degree F value is not for maximum temperatures, but more like an average or "normal" temperature.

Three tips that will prevent you from having issues when installing NM cables in attic spaces.

1. Don't bundle cables thru fireblocking or draftstops.
2. Don't run the cables where they will be embedded in insulation.
3. Keep the loads limited to a value below what is permitted by code.