Messenger cable grounding question

[aklimok]

Hi,

Our church recently added some additional parking lights. They'll be running a 20amp/120volt #6 triplex between 3 poles. On the first pole there will be a switch disconnect for the entire series. From the breaker panel to the disconnect, the wiring will be a hot, neutral and ground, in conduit underground. From the disconnect, 2 insulated conductor (hot and neutral) will go up to the lights. This is because lights are designed in a plastic enclosure and a ground is not required for them. My question is the messenger cable need to be grounded? Rule 396.60 requires messenger cables to be grounded, however there exceptions in Rule 250.86 which state no messenger cable is required when:

(1) Do not provide an equipment ground
(2) Are in runs of less than 7.5 m (25 ft) [b][I]our distance is greater than 25 feet[/I][/b]
(3) Are free from probable contact with ground, grounded
metal, metal lath, or other conductive material
(4) Are guarded against contact by persons

Question 2:
For splice pigtails from lights, there will be a split bolt used and then insulated with rubber tape. Is this enough or is something else required? What is the best type of wire to use from pigtails to the main line?
Or perhaps someone has a better suggestion on how to set this up?

Thanks.

 

[gndrod]

Hi,

Our church recently added some additional parking lights. They'll be running a 20amp/120volt #6 triplex between 3 poles. On the first pole there will be a switch disconnect for the entire series. From the breaker panel to the disconnect, the wiring will be a hot, neutral and ground, in conduit underground. From the disconnect, 2 insulated conductor (hot and neutral) will go up to the lights. This is because lights are designed in a plastic enclosure and a ground is not required for them. My question is the messenger cable need to be grounded? Rule 396.60 requires messenger cables to be grounded, however there exceptions in Rule 250.86 which state no messenger cable is required when:

(1) Do not provide an equipment ground
(2) Are in runs of less than 7.5 m (25 ft) [b][I]our distance is greater than 25 feet[/I][/b]
(3) Are free from probable contact with ground, grounded
metal, metal lath, or other conductive material
(4) Are guarded against contact by persons

Question 2:
For splice pigtails from lights, there will be a split bolt used and then insulated with rubber tape. Is this enough or is something else required? What is the best type of wire to use from pigtails to the main line?
Or perhaps someone has a better suggestion on how to set this up?

Thanks.

I am not sure where the messenger cable comes into play from your description if everything is underground. The bonding from the EGC is required at every pole j-box to bond the pole and/or if the conduit is PVC. A messenger would normally be associated with an overhead drop in my understanding. rbj

 

[aklimok]

Sorry, this will be an overhead run. The messenger cable will support the wires from pole to pole.

 

[gndrod]

Sorry, this will be an overhead run. The messenger cable will support the wires from pole to pole.

OK, so the Triplex messenger cable is a grounding conductor with the phase and grounded return. The messenger grounding cable run (with the phase conductor) needs to be bond connected down to the switch box in a protected raceway. rbj

 

[dalesql]

I'd ground the messenger anyway, because of the potential for lightning strike.
You already have the grounded neutral which will act as bait for the lightning bolt, and then conduct all that energy right into the panel. Grounding the messenger cable will tend to have the bolt take that path to earth, hopefullly reducing the damage to all the other electrical gear in the building.

 

[tom baker]

Regardless of what 250.86 states, 250.134 requires fixed equipment to be bonded.
And 250.86 is in Part IV which deals with service conductors so does not apply to your application.
The rules in different parts don't apply unless there is a reference and of course, part I applies to all parts.

 

[zbang]

I often wonder why people as "do I need to ground this?" when I'd rather they ask "Any reason -not- to ground this?"

If the poles are metal with reinforced concrete bases, then wrapping the messenger around the pole will create a path to the earth (and the poles will need bonding). If the poles are wood, I think you'll want a rod to earth the messenger for lighting protection. (not awake enough to crack the book on this).

 

[Nium]

Or perhaps someone has a better suggestion on how to set this up?

I would think if you hired a qualified electrician they would be able to answer all your questions on how this project needs to be correctly wired and installed, but that's just my 2 cents worth.