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4" PVC RMC

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A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
Hello. Have 40- 4" RMC PVC coated conduits running on roof about 500'. Would derating need ot be taken into consideration and how would that be calculated? Below is ther info. 500' on roof and 170' inside building.

Trip (A)Modeled LengthWirefill
2700670' - 7 1/4"4#600MCM CU+1#500MCM G
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Why are we referencing 2008 NEC? Is there even any jurisdictions still using 2008? That is a 16 year old document by now, and actually is getting close to 17 years since it was first released.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
2023 NEC is simple, if raceway or cable is less than 3/4 inch above the roof, you need to add 30C to your outdoor temperature.

Note this means you still possibly need to make adjustments if your raceway/cable is 3/4 or more above the roof, all depends on what the outdoor temperature can be like in your application, there just isn't as much for extreme temp adders like they put in back in 2008 NEC.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
kwired said:
Why are we referencing 2008 NEC? Is there even any jurisdictions still using 2008? That is a 16 year old document by now, and actually is getting close to 17 years since it was first released.
Click to expand...
The OP is in NYC which is on the 2008 NEC.
 
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