5 conductor power cable

[tonype]

What is the use for a 5-conductor power cable? My limited research leads me to conclude it is for some heavy industrial type use. Saw a house that had one feeding a sub panel from the main. One of the conductors was a dummy and not used/connected on either end (had a purple line on the black insulation).

 

[WorkSafe]

I know we have 5-wire cabling that powers our electrical spider boxes in our aircraft hangers:

http://www.grainger.com/Grainger/HUBBELL-WIRING-DEVICEKELLEMS-Ground-Fault-4D577

 

[tonype]

Anything wrong with use in a residence in the manner described?

 

[jumper]

I use 5 conductor MC cable all the time. 3 hots, neutral, ground. Quite common in commercial.

 

[GeorgeB]

I know we have 5-wire cabling that powers our electrical spider boxes in our aircraft hangers:

http://www.grainger.com/Grainger/HUBBELL-WIRING-DEVICEKELLEMS-Ground-Fault-4D577

I don't know why you'd have 5 wire feeding THAT box; I don't see the 50A plug specification, but strongly suspect it is 4 wire.

If you were supplying a spider box with 208-3-60, 5 wire would be used, GEC (neutral), ECG, A, B, and C. Receptacles would vary with the requirements, perhaps single phase 208 (2W/G), single phase 208/120 3W/G), 120 (2W/G), 3 phase 208 (3W/G), and even 3 phase 208 with 120 loads, 4W/G. 120V receptacles probably would require GFCI.

 

[WorkSafe]

I don't know why you'd have 5 wire feeding THAT box; I don't see the 50A plug specification, but strongly suspect it is 4 wire.

If you were supplying a spider box with 208-3-60, 5 wire would be used, GEC (neutral), ECG, A, B, and C. Receptacles would vary with the requirements, perhaps single phase 208 (2W/G), single phase 208/120 3W/G), 120 (2W/G), 3 phase 208 (3W/G), and even 3 phase 208 with 120 loads, 4W/G. 120V receptacles probably would require GFCI.

No, not that specific spider box I linked. I don't know the specifics of it, but do know I happened to trip over said cable yesterday afternoon.

 

[socalelect]

http://cepnow.com/?p=392
i think these are what he is refering to that take a 5 wire feed

 

[kwired]

Could be used for the rare two phase systems.

Could be used between a reversing controller and a single phase motor (essentially is a two phase motor).

Or even between a controller and a three speed single phase motor. (common, speeds 1,2,3, G)

I may think of a few other uses.

Add: possibly DC motors

 

[hurk27]

Sounds like tray cable with the purple stripe on it. also I have seen a 5-wire SJO cable, now the question is which one is it?

If this is tray cable, 336.12 doesn't specifically prohibit using it for this application but Ampacity for it is much more restrictive because of the derating required, see 336.80, also 336.12(1) can make it required to be protected.

 

[augie47]

Anything wrong with use in a residence in the manner described?

I agree with Wayne in Post #9.
Check to see what type cable is being uses. If it is TC, the way I read 336.12, it must be in a raceway unless it is direct buried or used in an industrial establishment per 336.10(7).
If it is TC cable, the residential application you note would be against the NEC unless the cable is in conduit IMO

 

[tonype]

There was no cable tray or conduit - outer sheathing had no markings on it.