Pull Box

[timm333]

NEC 314.28-C allows larger and smaller conduits in the same pull box. Can we install three different types of conduits in the same pull box, where the first conduit is with 4160V cables, the second with 600V cables, and the third conduit with communication (fiber optic) cables?

 

[texie]

NEC 314.28-C allows larger and smaller conduits in the same pull box. Can we install three different types of conduits in the same pull box, where the first conduit is with 4160V cables, the second with 600V cables, and the third conduit with communication (fiber optic) cables?

No. See 300.3(C)(2).

 

[timm333]

Yes that makes sense to separate 600V and 4160V conductors. However fiber optic cable is sometimes integrated inside medium voltage cable. For example, a 34.5kV 3-phase 4-core submarine cable would have 3 cores of 34.5kV power, and 1-core of fiber optic. Will it be possible to put the fiber optic cable in the same pull box as the medium voltage conductors?

 

[kwired]

General rule is no. Should your pull box have dividers making it effectively more then one pull box and you don't cross over any conductors prohibited to be in a particular enclosure...

 

[augie47]

As far as mixing >600v with 600 volts or less, 300.3(C) pretty much limits the procedure to some specific situations,
770.133 seems to permit non-conductive fiber optic cables to occupy the same enclosures,

 

[electricalist]

This doesnt apply to this thread directly. I appalogize but in a situation where sheilded control wire would be used. Would using 600 v wire instead of sheilded be acceptable so that it may be ran in same conduit as other 600v rated circuits. Or is the seperation of them about the safety that a lv circuit could become line voltage

 

[augie47]

Sharing raceways and enclosures with more than one voltage or type cable involves 300.3 as well as Art 725, and Chapter 8 where applicable. There are few "one size fits all" rules and a shielded cable will not often effect the appropriate rule.

 

[kwired]

This doesnt apply to this thread directly. I appalogize but in a situation where sheilded control wire would be used. Would using 600 v wire instead of sheilded be acceptable so that it may be ran in same conduit as other 600v rated circuits. Or is the seperation of them about the safety that a lv circuit could become line voltage

Insulation rating is more important when it comes to mixing voltage rating - the shield is not there for insulation purposes it is there for EMF interference of the contained conductors.

However just using 600 v insulation still doesn't allow you to run something like a class 2 control circuit with either class 1 control circuit or with power conductors in same raceway.

 

[electricalist]

Ty sir ill put that in my notes.and read up on class types

 

[timm333]

NEC Table 314.16(A) gives standard sizes for smaller outlet/device/junction boxes. Is there some similar table for the standard sizes for larger pull boxes; for example there is a pull box 36"L x 36"W x 6"D: how to confirm that this is a standard size?

 

[kwired]

NEC Table 314.16(A) gives standard sizes for smaller outlet/device/junction boxes. Is there some similar table for the standard sizes for larger pull boxes; for example there is a pull box 36"L x 36"W x 6"D: how to confirm that this is a standard size?

No. Table is there for smaller boxes for convenience. Those smaller boxes is also where you typically are concerned about volume for smaller conductor fill. If a box is not a standard size in the table it will often have it's volume marked on it - especially common with non metallic boxes. With larger conductors (and inherently larger boxes) you are more concerned with size for bending/pulling space then you are for volume. There may or may not be industry standard sizes in these larger boxes but there is no NEC standard sizes.