grounding 480V street lighting circuits

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goillinisparky

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We have an existing street lighting circuit that is fed by a 2400V/480V single-phase transformer. One phase is grounded. The circuit goes to the poles in direct-buried cable with no Equipment Grounding Conductor (The ld ways are not always the best ways!) Incorrect, I know, but that is how it is.
The circuit is to be refed from the other end due to a new building being built.

I am wondering if this system is required to be grounded.
250.20B requires the following systems to be grounded:
(1) if you can limit voltage-to-ground to 150V NO in this case (480V to ground)
(2) if it is 3p/4w Y NO in this case
(3) if it is 3p/4w D NO in this case

Question #1: Am I correct to say it doesn't need to be grounded?
Question #2: Would they be better off if the circuit to the poles was from an ungrounded system, since it would seem that it eliminates the danger of the pole becoming energized and shocking someone, since the system would have virtually no potential to ground?
Question #3: Any other idea on how to fix this, without digging it all up and installing an EGC?

Thanks for the help
 
Is this street light under the control of a utility? It is common utility practice and allowable by the NESC to omit the EGC and use the grounded conductor (neutral) to bond metal parts back to the source.
 
Peter,
thanks for the reply.
I am not in the street lighting department, but I'll give all the info I can.
The lighting is under the control of the University. We have our own power plant generating the MV electricity. We control everything from generation to receptacles and lights.
So, it may be a gray area as far as whether we are a utility or not. In my opinion, it is a utility, but what is my opinion worth??? :)

I suggested the idea of using the grounded leg to ground all of the poles, so that there is some way to open the OCPD of the circuit if there is a problem at the poles. My boss is worried about stray voltage and the surface voltage gradients around the poles.

Thanks for your help.
 
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