Yoopersup;
Please excuse me jumping in so late, but I have a couple questions to ask, and a few suggestions.
1: The Transformer at the end of this Loop (Circuit): Will the loads connected only be Line-To-Line 208V 1 Phase 2 Wire, or will there be 120V _AND_ 208V loads?
2: Do the connected loads require 208V 1 Phase 2 Wire, or could 240V 1 Phase 2 Wire be used?
3: Any possibility for 3 Phase loads in the future?
* The 208V 1 Phase 2 Wire Primary may be #6 with 55 Amp 2 Pole breaker.
* The Secondary Conductors may be protected by the Primary OCPD, since there is only ONE (1) derived Voltage from the Transformer's output (480V).
* Suggest to size the complete Circuit per the 10 KVA Transformer capacity.
This would include:
a:) The 480V Transmission Feeders (sized for 21 Amps, and adjusted for the Voltage Drop across 3500 feet of Conductor),
b:) The 208V Primary Feeder (55 Amp OCPD, #6 Feeders, #10 EGC),
c:) The Secondary Feeders at the step-down ("Last") Transformer.
* You might consider Grounding one side of the 480V output on the first Transformer.
This is an option, but for a stable Secondary Voltage to Ground, connecting the Transformer to a GES (Grounding Electrode System) is suggested.
* Suggest to Ground the Secondary of the "Last" Transformer to a local GES.
If the System derived from the "Last" Transformer is to be a "Dual Voltage" (120/240), _DEFINITELY_ Ground the Center Tap of the Transformer to a GES.
I can draw schematics for this scenario if needed.
Lastly, is this an actual proposed installation, or a "What-If" scenario?
Looking forward to your reply.
Scott
