Liquidtight Flexible Metal Conduit Operating Temperature

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xguard

Senior Member
Location
Baton Rouge, LA
350.12 Uses Not Permitted
LFMC shall not be used as follows: (2) Where any combination of ambient and conductor temperature produces an operating temperature in excess of that for which the material is approved.

Can a 75 degree C or 90 degree C conductor be used at it's full ampacity rating if it's installed in LFMC that has a temperature rating of 60 degree C?

If not how would you arrive at the allowable ampacity and ambient temperature it could be used at?
 

infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Your circuit ampacity cannot exceed the 60? C rating of the conductors. This would also be after you made any ampacity corrections for ambient temperature if required. So if you use say #8 THHN with 75? C terminations (which has an ampacity of 50 amps) you would still need to limit the circuit to the 60? C ampacity (40 amps) because the 60? C LFMC would be the "weakest link" in the installation.
 
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