tapping from lighting circuit?

[wsbeih]

I am working on a project in industrial plant where an internal street is being modified to have a truck loading area and it has a small guard shack.
We need around two new street lights and some service for the shack (lighting and sockets).
we don't have nearby panels to feed the new loads. Can I spur (tap) from nearest street light to feed the new 2 street lights and a new 1 kva transformer to feed the shack?

 

[augie47]

It would in all probability be Code legal to do so. There are a number of details you need to consider beginning with existing voltages and loads, voltage drop and secondary loads.
This is a case where without question the devil is in the details

 

[mgookin]

The first things I would look at are a load calculation and conductor size feeding to where you want to tap it. No a/c in that guard shack in Houston?

 

[GoldDigger]

It would in all probability be Code legal to do so. There are a number of details you need to consider beginning with existing voltages and loads, voltage drop and secondary loads.
This is a case where without question the devil is in the details

One detail that I would consider is that although the light poles may have individual photocell controllers, any time work is being done on any pole in the circuit you will lose power to the guard shack. Maybe plan on bringing in a small portable generator for those situations?

 

[cadpoint]

I've walked into enough plants to know out right that there is no additional power in any circuit. Most all are sized and run accordingly.

My second thought is does this plant have a real electrical dept. verses the house electrician? Along the same lines of do they have a on-site contractor doing all the work, and the electrician does something else.

I'm leading up the real question of what are the status of the existing electrical plans?
My belief is you will find the real answer(s)((like some above)) when you get into some circuit tracing, after you have all your base power requirement, as stated!

 

[mgookin]

One detail that I would consider is that although the light poles may have individual photocell controllers, any time work is being done on any pole in the circuit you will lose power to the guard shack. Maybe plan on bringing in a small portable generator for those situations?

Digger: Aren't they likely paralleled from the hand holes? A thug could shoot out one light and the rest stay lit. This guy is an engineer. I'm sure he can look at the OCPD and the conductor size and do a simple calculation and determine if he can add some load to an existing circuit. It's done every day.

 

[GoldDigger]

Digger: Aren't they likely paralleled from the hand holes? A thug could shoot out one light and the rest stay lit. This guy is an engineer. I'm sure he can look at the OCPD and the conductor size and do a simple calculation and determine if he can add some load to an existing circuit. It's done every day.

All that I am saying is that any time somebody needs to de-energize any one of the existing poles for maintenance, they will just turn off the whole lighting circuit and do the work during the day. That will, however, also turn off the guard shack. If the only need for power to the shack is for lighting, then no problem.

I would not expect somebody to disconnect a live parallel connection inside a hand hole so that they could change out a fixture, nor would OSHA. If you want to do that, you are free to.

I would also start by confirming whether there are individual photocells on each pole or whether there is a master control for the whole lighting circuit.
Even if the guard does not need any A/C or other electrical equipment, it would be nice to at least have a battery charger for his radio.

 

[tish53]

If the guard shack just needs lighting today, what will they put in it later. 2 years from now when they add the air conditioner, the computer, the badge reader, etc., no one will think about where the power comes from.

I would spend the money to give it a proper labeled feeder, not tapped from a lighting circuit.

 

[kwired]

This "lighting circuit" can be up to a 50 amp circuit and still be NEC compliant depending on exactly what kind of luminaires are supplied. If you have a compliant 50 amp circuit but do not have the load to max it out, it certainly would get the job done.

Problem is by adding the guard shack you now are turning the lighting circuit into a feeder as well. I have been in this discussion before with no real consensus if a circuit can have characteristics of branch circuit and feeder, but there seemed to be a few more leaning toward not being able to do so.