# ENT Smurf in Attics



## jar546 (Aug 10, 2019)

Can ENT, aka "Smurf" be used in an attic where you live?  ENT (Electrical Nonmetallic Tubing) is typically blue or gray but can be other colors.


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## cda (Aug 10, 2019)

Yes normally,  but there are some limiting factors


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## jar546 (Aug 11, 2019)

cda said:


> Yes normally,  but there are some limiting factors



Limited factors such as?


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## jar546 (Aug 11, 2019)

One of the limited factors is the ambient temperature of the attic.  According to the NEC 362.12(3):

_(3) Where subject to ambient temperatures in excess of 50°C
(122°F) unless listed otherwise_

Then, upon looking at the specifications from Carlon, one or the largest producers of ENT I found this:

_• ENT ambient temperature range -4 deg F (installation) to 122 deg F_

So the question then becomes:  How do you determine attic ambient temperature?  Ambient temperature is not an average temperature, it is the highest actual temperature at a given moment.  Attic temperatures in Minnesota, for example have been recorded at over 150F on a summer day.  With that being said, factors such as type of attic ventilation and color of roof does have an affect on attic ambient temperature.  Soffit and ridge vent systems have a lower attic temperature than soffit vents alone and a tile roof has a much lower attic ambient temperature than asphalt shingles.

In my opinion (yours may vary) I cannot see ENT (Smurf Tube) being code compliant if installed in an attic space unless the tubing is listed and labeled for higher temperatures.  I would, however, not have any issues with ENT in a non-vented attic where the underside of the roof sheathing was insulated and the thermal envelope.  At that point, the attic space itself is inside the thermal envelope.

Thoughts?


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