My costumer wants to power up some existing lights in a commerical building that has the service disconnected and service wires removed. Six foot away is another building with power in it, my plans are to run a short span of triplex from one building to the other and supply the lights with a single 20 amp circuit. Is this installation ok if I supply a service rated disconnect and bond the ground to the existing equipment?
Just remember to isolate the neutral in the second building and this is pretty straight forward. Bond the EGC to the building grounding system, connect your lighting circuit to the disconnect from your feeder.
If you are using triplex to feed the second building you will not isolate the neutral and will be providing a new ground electrode connected to the new neutral. If you are housing livestock in the second building this is the only permissable way to do this unless a tingle voltage isolator is installed between the ground and neutral. If you are feeding the second building with ACWU, teck90, pipe and wire then you may run a bonding conductor to the second building panel and isolate the neutral from the ground.
You must bond the Equipment Grounding Conductor of the branch circuit to the existing Grounding Electrode System. If you run quad-plex you can use either a multi wire branch circuit or if it's thirty amperes or more you can use it as a single phase feeder to supply the existing equipment. -- Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison