Nec 725.3(C)

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erickench

erickench

Senior Member
Location
Brooklyn, NY
The above NEC section state's the following:

Class 1, Class 2, and Class 3 circuits installed in ducts, plenums, or other space used for environmental air shall comply with 300.22.

Has anyone ever seen a Class 1 circuit inside a duct or plenum or environmental air space? Mike Holt's book "Understanding the NEC" seem's to have left out Class 1 but included Class 2 & 3.
 
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nhfire77

Senior Member
Location
NH
erickench said:
The above NEC section state's the following:

Class 1, Class 2, and Class 3 circuits installed in ducts, plenums, or other space used for environmental air shall comply with 300.22.

Has anyone ever seen a Class 1 circuit inside a duct or plenum or environmental air space? Mike Holt's book "Understanding the NEC" seem's to have left out Class 1 but included Class 2 & 3.
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Wouldn't class 1 circuits require chapter 3 wiring methods?

And then the circuit is in the raceway (e.g. EMT) , not the plenum.
 
ericsherman37

ericsherman37

Senior Member
Location
Oregon Coast
Old skool style maybe, like using the area above a dropped ceiling (or area below a raised floor) as air handling space. I don't think anyone does that anymore, but I dunno.
 
LEO2854

LEO2854

Esteemed Member
Location
Ma
erickench said:
The above NEC section state's the following:

Class 1, Class 2, and Class 3 circuits installed in ducts, plenums, or other space used for environmental air shall comply with 300.22.

Has anyone ever seen a Class 1 circuit inside a duct or plenum or environmental air space? Mike Holt's book "Understanding the NEC" seem's to have left out Class 1 but included Class 2 & 3.
Click to expand...

Look at 725.154(A)
 
erickench

erickench

Senior Member
Location
Brooklyn, NY
LEO2854 said:
Look at 725.154(A)
Click to expand...

That's just it. This NEC section that LEO2854 quoted only has rules for Class 2&3 circuits and not for Class 1. One would think that it's not common industry practice to install Class 1 circuits using metal raceway inside a duct or plenum or environmental air space.
 
J

jusme123

Senior Member
Location
NY
Occupation
JW
for class 1 wiring methods see 725.46

motor control ckts using a 120v are Class 1 wiring, meaning any device located in duct work or air chamber has to comply with class 1 wiring methods (725.46 which in most cases leads you to art. 300)
 
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nhfire77

Senior Member
Location
NH
That should be interesting. A lot of folks have trouble with the plenum or other space definition.

I would say that class one circuits are uncommonly run through plenums and if they are they must use chapter three wiring methods.

I never thought of it until you asked.
 
don_resqcapt19

don_resqcapt19

Moderator
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Location
Illinois
Occupation
retired electrician
erickench said:
That's just it. This NEC section that LEO2854 quoted only has rules for Class 2&3 circuits and not for Class 1. One would think that it's not common industry practice to install Class 1 circuits using metal raceway inside a duct or plenum or environmental air space.
Click to expand...
Installations within a duct or plenum are very limited by the rules in 300.22 and are not common. Installations in "other space used for environmental air" are common and covered by 300.22(C). Class 1 Circuits use Chapter 3 wiring methods and where installed in "other space used for environmental air" are to be installed per 300.22(C).
 
Pierre C Belarge

Pierre C Belarge

Senior Member
Location
Westchester County, New York
erickench said:
I'm preparing a powerpoint presentation for continuing education for PEs. I need to have this question answered.
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For your PPT presentation:

Class 1 installations in 300.22 locations is not a typical type of installation in the industry.
If one should be inclined or find it necessary to have this wiring method installed in the location, follow the requirements of 300.22 and Part II of Article 725.
 
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