I have a street lighting situation:
Large campus with many street light poles.
Fed by a back wired D-Y 480/208 transformer.
Campus voltage is 3 phase 120/208.
We own all of our transformers, service comes from power company at 13,800
volt and is stepped down to 120/208 at each building.
The existing street lighting is 480 volt and has no reference to ground because the DELTA secondary of the particular lighting loop is not grounded.
Typically each building has its own street lighting transformer (15 KVA) stepping the buildings 208 up to 480 via the DELTA WYE back fed.
I know that this is extremely unsafe and I would like to make it safe.
To top it all off; the poles are fed via underground pvc pipeline with NO GROUND WIRE.
My intention is to pull in the proper sized ground wire and to "corner ground" the secondary delta so that the overcurrent device will see a short from phase to ground.
The manufacturer says that this is typically how to establish a ground reference.
I get mixed reactions from other electricians about this plan.
I just want to make the street lights safe so that our campus is not on the six o'clock news with another horror story.
Large campus with many street light poles.
Fed by a back wired D-Y 480/208 transformer.
Campus voltage is 3 phase 120/208.
We own all of our transformers, service comes from power company at 13,800
volt and is stepped down to 120/208 at each building.
The existing street lighting is 480 volt and has no reference to ground because the DELTA secondary of the particular lighting loop is not grounded.
Typically each building has its own street lighting transformer (15 KVA) stepping the buildings 208 up to 480 via the DELTA WYE back fed.
I know that this is extremely unsafe and I would like to make it safe.
To top it all off; the poles are fed via underground pvc pipeline with NO GROUND WIRE.
My intention is to pull in the proper sized ground wire and to "corner ground" the secondary delta so that the overcurrent device will see a short from phase to ground.
The manufacturer says that this is typically how to establish a ground reference.
I get mixed reactions from other electricians about this plan.
I just want to make the street lights safe so that our campus is not on the six o'clock news with another horror story.