On Thu, 22 Jan 2009 12:54:04 -0800, David Nebenzahl
Bear in mind the NEC is not a design manual. Proper conductor
management is crucial but that is not defined in the NEC.
Typically the convention is 120/208 wye will be black/red/blue with a
480 wye will be Brown,/Orange/Yellow with violet/gray for the 277 line
The rub comes in when you have 240 center tapped delta because then
the code requires orange be used for the 208 leg. If this was also in
a building with 480 you could have some confusion. In real life I have
never seen them together. Typically 240 delta is only in a light
industrial area where they are trying to save money (2 transformers)
or where they really want 240v 3p.
The only place I have ever seen delta with 3 transformers is behind
the Hog's Breath Saloon in Key West (look up at the pole behind the
outside stage). I bet they just "grew" into that situation
You are right. If there are different voltage systems in the same
building (not just the same conduit) the NEC requires an identification
scheme. The scheme has to be readily available, which may be by posting
on the panels. Requirements have tightened over the last few code cycles.
Schemes I have seen are the same as what gfretwell posted.
Those have become so much of a national standard that AFC is selling
MC cable with those mixes and the colors painted on the jacket for
instant ID. It makes it real easy for inspectors and maintainers to
figure out what the installer was doing.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.