EMT permitted use

[schole]

Where can I find a reference to permiited use of EMT on 4160V 3w system within an industrial plant.

 

[billdozier]

Do you know if this is a class 2 div 1 or higher area? If its not id say you should be able to use emt . My only question is the voltage. However im not aware of a code speaking solely to voltage see art 358.12 (4)

 

[masterinbama]

I have used EMT for 4160 volts before ,but for safety's sake we labeled it every 5' or so.

 

[ron]

NEC section 358.10

 

[chicar]

Thier is no limit of voltage concealed by emt as long as the wires are rated properly and the conduit is sized properly for the wires.

 

[chicar]

Could someone explain what 358.30[c] 2008 mean ?

 

[480sparky]

Could someone explain what 358.30[c] 2008 mean ?

Means you don't need to support continuous lengths 18" or shorter between boxes, panels, etc.

 

[celtic]

Could someone explain what 358.30[c] 2008 mean ?

358.30(C) Unsupported Raceways.
Where oversized, concentric
or eccentric knockouts are not encountered, Type EMT
shall be permitted to be unsupported where the raceway is
not more than 450 mm (18 in.) and remains in unbroken
lengths (without coupling). Such raceways shall terminate
in an outlet box, device box, cabinet, or other termination at
each end of the raceway.

Basically, it says a punched hole or exact sized factory KO with less than 18" of EMT needs no support if you use no couplings.

 

[chicar]

So you mean like stubs. I allways thought that they could be at least 24"

 

[DRGREG]

Up to 18" of EMT can be installed between 2 boxes, if KOs are drilled or punched to size. But if the KOs are oversized, concentric or eccentric the EMT would have to be supported. Example; 2" EMT 6"long between two boxes with one or more concentric KOs would need a strap.

 

[480sparky]

So you mean like stubs. I allways thought that they could be at least 24"

24" is the 'nipple' rule from Ch. 9, Note 4, and deals with fill ratios and derating, not support issues.

 

[celtic]

So you mean like stubs. I allways thought that they could be at least 24"

You are confusing the 24" no derating train of thought [Table 9; Note 4] with the 18", exact size, no coupling train of thought [358.30(C)] :grin:

 

[dcspector]

Basically, it says a punched hole or exact sized factory KO with less than 18" of EMT needs no support if you use no couplings.

That is a great summary of that section....well said my friend :smile:

 

[celtic]

That is a great summary of that section....well said my friend :smile:

I think 480 gets some "props" here too.....there seemed to be some sort of an echo effect happening there :grin:


TY DC

 

[chicar]

I understand now. Thanks fellows and happy new years.

 

[jrock0305]

we always paint our high voltage conduits boxes etc red and label it PERMANTELY good job for the new guy