480 volt sports lighting

[Mountain Sparky]

There is a ball field with sports lighting that was wired in the 70's. About 8 years ago new metal poles and lighting were installed. The existing 3 phase 480 volt service and underground wiring was left and reused. The pole lights are single phase 480 volt fed from a fused disconnect with 2 conductor direct bury wiring, there is no equipment ground. Each pole is bonded to a ground rod. If a conductor was to make contact with a pole would the fuse blow?

 

[GoldDigger]

There is a ball field with sports lighting that was wired in the 70's. About 8 years ago new metal poles and lighting were installed. The existing 3 phase 480 volt service and underground wiring was left and reused. The pole lights are single phase 480 volt fed from a fused disconnect with 2 conductor direct bury wiring, there is no equipment ground. Each pole is bonded to a ground rod. If a conductor was to make contact with a pole would the fuse blow?

At 480V (or less to ground than line to line) it would be a toss-up. It would depend on exactly how low the resistance of each ground rod was.
For example:
Assume the ground rod's earth resistance is 25 ohms (for no particular reason. It might be better, but likely would be worse.)
Voltage to ground is 277V or thereabouts (assuming a grounded wye with line-to-line loads.)
Current = 277/25 = 11A. Not very likely to trip a 30A breaker!

A metallic EGC is critical for a situation like this. It is a life safety issue.

Or, you could install breakers with Ground Fault Protection to cover all of the circuits. Not NEC compliant by itself, but a lot safer.
If you mean that you have a 480V wye and are feeding one hot and one neutral to each pole the situation gets better, but still not acceptable.

 

[iwire]

In my opinion this is about as dangerous as anything can be.

If I found this I would refuse to service it and do as much as I could to get the people in charge to understand that this has a high probability of hurting or killing someone at some point.

The ground rod does absolutely nothing to increase the safety of this dangerous condition.

 

[iwire]

A metallic EGC is critical for a situation like this. It is a life safety issue.

I agree 100%

Or, you could install breakers with Ground Fault Protection to cover all of the circuits. Not NEC compliant by itself, but a lot safer.

I disagree with this and would not even mention it to the people in charge of this lighting.

 

[don_resqcapt19]

This should have an immediate red tag and the power disconnected until the system can be brought into compliance with the code rules. The adopted electrical codes in many areas give the inspector this power for installations that are a serious and immediate danger to the public. It is my opinion that the current installation is a serious and immediate danger to the public.

 

[ggunn]

There is a ball field with sports lighting that was wired in the 70's. About 8 years ago new metal poles and lighting were installed. The existing 3 phase 480 volt service and underground wiring was left and reused. The pole lights are single phase 480 volt fed from a fused disconnect with 2 conductor direct bury wiring, there is no equipment ground. Each pole is bonded to a ground rod. If a conductor was to make contact with a pole would the fuse blow?

Do you mean that each pole is fed by a pair of 480V phase wires, or are they fed with a single phase and a neutral, which would actually be 277V? I believe that is a lot more common. But it's unsafe as hell in either case, IMO.

 

[iwire]

Do you mean that each pole is fed by a pair of 480V phase wires, or are they fed with a single phase and a neutral, which would actually be 277V? I believe that is a lot more common.

We install and service a lot of outdoor lighting that is supplied 480 volt.

A common way (in my area) to light large lots is to run all three phases of a 480 volt circuit to each pole and alternate which two phases you connect the lights too.

A-B at first pole, A-C at second pole, B-C at third pole doing that as many times as needed. It helps with voltage drop. The down fall of this is it all comes from one 3 pole breaker and if it trips you lose a lot of lighting.

 

[Mountain Sparky]

solution

solution

thanks for all the good advice. We are in the process of installing new conduit and wire. Once we made the owner aware of the issue, they had no problem replacing the wiring.