National Electrical Installation Standards

Standards as High as Your Own

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Wednesday, May 6, 2020

Question:

Greetings Code Question Staff,

Friday April 10th Question on the 120/240 Delta high-leg system. ANSI standard requires meter bases to use B phase for their operating voltage, which is 120 volts they will not work properly with a 208 to ground B phase. The B phase being the high voltage to ground and being marked orange did not appear in the NEC until 1975 most installations in our area before 1975 have the C phase as the high leg throughout the entire system and is marked red.

Jimmy Cagle

A

Answer:

Hi Jimmy!

Thanks for the note. The NEC has an exception for meters so the high-leg can remain on the C phase as you indicate. See Section 408.3(E) Exception. Yes, the red color was commonly used to identify high-leg conductors for years in many areas, but the Code did change to require the orange color to be used in recent editions of the Code. The requirement for this identification applies if a neutral conductor of the system is present.

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