Branch circuit to receptacle on pole

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smallfish

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An overhead triplex cable (a cable with two insulated and one bare with messenger aluminum conductors) strung from pole to pole in a parking lot is fed from a panel in a guard shack and supplies a receptacle in an enclosure for monitoring a turnstile entrance/exit to the lot. (The other phase conductor is capped and may be used at a later date.)
Is it code compliant to use the bare conductor as the neutral to this receptacle, bonding this neutral to the metal enclosure which is mounted on the wood pole and to a driven rod at the pole?
There is a data cable also strung to the pole with its own green ground wire fastened to a terminal on a board within the enclosure but isolated from it.
I refer to 250.32 (B) (2).
Thanks
 
No. The ground rod will never clear a line to case fault. For a single branch circuit a grounding electrode is not required.
This branch circuit requires a EGC, per 250.118. The neutral must be insulated, this requirement I can't find a code citation at the moment.
Keep in mind that not all triplex cable is listed, what the utilities use is not, you'll need to find listed triplex.
 
This exact installation is not compliant, though a similar installation _may_ have been compliant under earlier versions of the NEC.

In particular, for a 'detached structure', previous versions of the NEC permitted the neutral serve as the fault current path, in the same fashion that the neutral in a service provides the fault current path. At the detached structure, the neutral would be bonded to the grounding electrode system and to the equipment grounding conductors.

However, to use this permission, you could not have any bonded metal connecting the two structures. The ground wire of the communications cable would count as such bonded metal, thus rendering this installation not compliant.

I don't recall if this method could be used for an individual branch circuit, or if it only applied to feeders.

Additionally, this method of feeding detached structures was recently eliminated from the code.

-Jon
 
smallfish said:
An overhead triplex cable (a cable with two insulated and one bare with messenger aluminum conductors) strung from pole to pole in a parking lot is fed from a panel in a guard shack and supplies a receptacle in an enclosure for monitoring a turnstile entrance/exit to the lot. (The other phase conductor is capped and may be used at a later date.)
Is it code compliant to use the bare conductor as the neutral to this receptacle, bonding this neutral to the metal enclosure which is mounted on the wood pole and to a driven rod at the pole?
There is a data cable also strung to the pole with its own green ground wire fastened to a terminal on a board within the enclosure but isolated from it.
I refer to 250.32 (B) (2).
Thanks
Click to expand...

In this scenario, your neutral conductor is carrying return current and you are connecting this returning current to the metal on the pole which is accessible to contact by persons. You must have an insulated grounded conductor (neutral) and also an equipment grounding conductor (this could be bare) routed with the circuit conductors. If you drive a ground rod at each pole, you would connect it to the egc, not the grounded conductor which has return current on it.
 
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My thinking is: by bonding the neutral to the metal enclosure, any ground fault current on the enclosure would travel back on the neutral to open the OCPD. The driven ground rod bonded to the neutral and to the enclosure would serve to make metal turnstile, and the nearby metal fence and the faulted enclosure all at the same potental thus eliminating electrical shock.
 
smallfish said:
The driven ground rod bonded to the neutral and to the enclosure would serve to make metal turnstile, and the nearby metal fence and the faulted enclosure all at the same potental thus eliminating electrical shock.
Click to expand...
In a perfect world, perhaps, but in reality, you're more likely to energized that enclosure, turnstile, and fence.
 
Cow said:
Why not use the other insulated conductor as the neutral and the bare as the ground?
Click to expand...
I used some triplex to supply a receptacle, 1/2" EMT with weatherheads at both ends, and that's exactly what I did.
 
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