300.7 (a)

Merry Christmas
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Senior Member
Doesn't this cover all underground installations, and leaving conditioned spaces to the outside. I don't think I have seen anyone doing this,
and if you did is silicone what you would use?

300.7 Raceways Exposed to Different Temperatures.
(A) Sealing. Where portions of a cable raceway or sleeve are known to be subjected to different temperatures and where condensation is known to be a problem, as in cold storage areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled with an approved material to prevent the circulation of warm air to a colder section of the raceway or sleeve. An explosionproof seal shall not be required for this purpose.
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Staff member
New Jersey
Journeyman Electrician
Duct seal. Silicone can be a real mess and will be almost impossible to remove later on.
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