ECN Forum Forums Code Related Discussion NEC & other Code issues Color code for corner ground

The first one I saw confused me for a minute but I did know there was such a thing as corner delta so I did figure it out. (and pretty proud of myself that I did it before I said something dumb) The colors they used were red, blue and white. Very patriotic and also a fairly good indicator for a 240v 3p corner system, The fact that one wasn't black was a tip off that it wasn't standard 120/240 and 2 transformers on the pole was another cue that you had 3p.
Fortunately there was a wiring diagram in the starter that confirmed this was really 3 phase but it did not say anything about the grounding.

I think if I was doing 480 corner I would use brown/yellow/gray, just because gray is the common grounded conductor color on 480 and orange can cause confusion. BOY is a common convention on 480 wye but when delta is involved it is supposed to be the high leg if this was center tapped. Omitting it alerts you something else is going on. Actually I have heard a lot of people who want BOY to go away because of the high leg thing. I think it is so ingrained in the culture that it is probably here to stay.

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

Were you the engineer on record for local planning & permits, requiring a Class "A" license in California, or was this an industrial-maintenance project?

A Class "A" license General Engineering License isn't the license that's required. (That's more for building highways, power generation plants, bridges, and the like).

Any licensed PE can stamp the plans,

or

Read California Business and Professions Code Section 6737.3, which states that any licensed C-10 electrical contractor can engineer a job, as long as the contractor is performing the work himself.

Yes, I see:
DEERING'S CALIFORNIA CODES ANNOTATED cites one case decision under this statute, known formerly as § 6737.4:
Wynner v. Buxton (1979, 2nd Dist) 97 CA3d 166, 158 Cal Rptr 587, 1979 Cal App LEXIS 2163.
No liability was found against a PE who stamped plans "omitting all mechanical and electrical details which may be supplied by mechanical or electrical contractor".

Also see: CA B&P § 6747 Exemption for Industries.
Except for civil engineering, the performance of unlicensed-engineering work is permitted for corporate consultants, temporary employees, contract employees, and those persons hired pursuant to third-party contracts (handymen).

Why bother using licensed contractors at all, when CA B&P § 6747, permits corporations to use unlicensed maintenance-electricians and handymen to engineer electrical systems?

PROFESSIONAL ENGINEERS ACT
(Business and Professions Code §§ 6700 – 6799)
http://www.pels.ca.gov/licensees/pe_act.pdf

Ramsy,

Yes I was the Person responsible for the Preparations of the Documents.
This was a Design / Build Project; Contractor's License classes are B & C-10.

We perform Design / Build services pursuant to California B&P Code, Division 3, Section 6737.3.
("B&P" = Business and Professions Code)

Scott