I am only just curious about this local code amendment you are describing. Do they apply this to single phase 240/120 volt residential systems? If so, why? The system is single phase. Both hot conductors are on the same phase.
Yes, but not always enforced, the inspectors acually have to remind themselves about it.... And that reminder usually comes in the form of all black phase conductors, or big lumppy gobs of tape on them. Yes, in residential too. As not all residential is the same. Example mid and high-rise buildings are often 3 phase 208, but only using 2 phases, and there are parts of the city that have split delta systems and allowed the high-leg into the buildings (Big old mansions) for elevator use. As well as the many converted industrial areas that al now 'live/work'.... There are also a few 2 phase areas, and even if single phase the 'phases' are of are of additive voltage, so..... I see the point here.
Any this is that code....
210.5(C). Add the following new section:
(C) Ungrounded Conductors. Underground conductor insulation shall be color coded as follows:
See Section 200.7 for limitations on re- identification of white or gray conductors.
(1) 120/240 volt 3-wire circuits - “A” phase black, “B” phase red; 120/208 volt 4-wire 3-phase wye circuits - “A” phase black, “B” phase red, “C” phase blue; 120/240 volt 3-phase delta circuits - “A” phase black, “B” (high leg) phase purple, “C” phase red; 277/480 volt 4-wire 3-phase wye circuits - “A” phase brown, “B” phase orange, “C” phase yellow; ungrounded conductors for other voltages shall be identified by different color coding, marking tape, tagging, or other approved means.
(2) Conductors for switch legs may be ofa different color than the ungrounded circuit conductor when suitably identified at pull, junction and outlet boxes with marking tape, tagging or other equally effective means. The color green, white or grey shall not be used for identification.
(3) Conductor insulation shall contain the applicable color pigment for circuit wire #14 AWG through #10 AWG. Ungrounded conductors #8 AWG and larger and ungrounded conductors of any size in cable assemblies may be suitably identified at pull, junction and outlet boxes with marking tape, tagging or other equally effective means.
Exception: Extensions of existing non-color- coded wiring systems need not be color coded.
