I agree; more of the Field Personnel should be aware of the Corner Grounded Delta Systems - as they still are used in Industrial areas... (not to mention awareness of all other System types, but that's another post!).
Even more importance falls on the SDS from a "Reverse Connected Delta / Wye Transformer", and a solid + correctly Grounded output.
Per Color Codes and System Identifications, on all the Projects I have dealt with, where a Corner Grounded Delta was involved (either an SDS, the Utility supplied System, or both), Designs and Installations were targeted to clarification of System usage + capabilities.
Service Section / Transformer contained explanation - via schematics - why there are only Three Conductors - One being White (or Gray), on this 3 phase System.
Safety Switches (Disconnects) contained descriptive Schematics and text, regarding why the "B Phase" has no Fuse; and instead has a Solid Link".
Corner Grounded Deltas Color Coding was similar to Greg's description:
A = Red, B = White, C = Blue.
Where there was an SDS Corner Grounded Delta, the Color Code became:
A = Brown, B = Gray, C = Yellow.
Side Note:
I performed Engineering & Design work on a recent Industrial Project, which has Two Service Sections (One is Single Phase 3 Wire, the other is 3 Phase 3 Wire - both fed from a Utility Owned 4 Wire Delta Transformer), and to include a new 480V Corner Grounded SDS for Large Motor Loads.
Most of the Field Personnel had no clue as to the "Odd-Ball Power Systems", as well as my specifications on the Plans, regarding the output of the new SDS Transformer... such as:
"Grounding Phase B",
"Color Code for Phase B = Gray",
and
"No Fuse in Phase B at Disconnects - Solid Links only".
(There is much more information on the Plans than what I show here)
This resulted in me supporting the Field Crews.
They had never seen - or heard of Systems like this; but with some explaining, they were able to grasp the basics.
There were still many puzzled looks, though!
Color coding on this Project ran as follows:
System #1. 120/240V Single Phase 3 Wire (from Service #1 "Lighting"):
Line "A" = Black,
Line "C" = Blue,
System Grounded Conductor = White.
System #2. 240V Three Phase 3 Wire (from Service #2 "Power"):
Phase "A" = Black,
Phase "B" = Orange (High Leg),
Phase "C" = Blue.
System #3. 480V Three Phase 3 Wire (from SDS Transformer):
Phase "A" = Brown,
Phase "B" = Gray (System's Grounded Conductor),
Phase "C" = Yellow.
All Panelboards, Disconnects, Service Sections, and the Transformer contained Color Code charts denoting all Three systems.
Any comments?
Scott
