Does anybody know how we (the industry) decided that the primary phase colors should be BK-RD-BL for 208Y120 and BR-OG-YL for 480Y277? Any historical or code help would be appreciated since I have no clue other than to say "It's always been that way, it's tradition"

Hi Steve,
This is only hearsay, but I heard that the Brown, Orange, Yellow for 480 was decided on because it makes an easly remembered acronym BOY, so that electricians could remember the sequence when phasing out the wires.

Who knows?

FWIW, On Long Island we use the same colors for 208Y120 in another variation of the same order - Blue/Black/Red

I guess we just like to be different?


Bill

Bill, the province of Alberta and Western Area Power Administration {a federal bulk-power utility} use Red/Black/Blue for 208Y ‘ABC-123’ phasing

There are a number of institutional facilities that publish their “Division 16” (electrical) design standards online.

I learned Brown-Violet-Yellow {Gray} for 480Y/277V phasing in the 1970s.

ucdavis.edu wsu.edu ohio-state.edu and others list the “B-O-Y” 480V code for ‘ABC-123’ phasing.

stanford.edu lists 277/480V 3P 4W… normally Brown, Purple or Orange, Yellow, Gray or White, as does GE metering-retrofit instructions.

berkeley.edu {and sister facilities} list Brown, Yellow, Purple, and White for 480Y/277V systems, as does ci.brisbane.ca.us. Aside—“B-Y-P” in Berkeley evolved from their 1950s standard of Black-Yellow-Green(!) for 480V ∆ systems. Bare copper was the mandatory equipment-grounding conductor within all raceways and enclosures—metal or otherwise. [Green-jacketed grounding conductors are now permitted, but there is tons of existing gear with bare equpemnt grounds.]

The Omaha 480Y/277V utility network ABC-123 phasing is Brown, Orange and Purple in their standards.

Lithonia Lighting shows Yellow-Brown-Orange-White for 480Y/277V.

Last but not least, the City of San Francisco calls out Black-Violet-Blue for 240V 4W∆, to not conflict with the 480V B-O-Y code. Many others use Black-Orange-Blue for 240V 4W∆.

The choice of colors, and how they've changed over the years always fascinates me.

Just how common was it for green to be designated a phase in the past? Was this a "Berkeley special," or did other places use it as well?