Services & DistributionQuestion 110 of 521
On a 4-wire delta system where the midpoint of one phase is grounded, the conductor with the higher voltage to ground (the high leg) must be durably and permanently marked, typically colored:
a.Orange
b.Blue
c.White
d.Green
Explanation
Per 110.15, the phase conductor having the higher voltage to ground (about 208 V on a 120/240 V high-leg delta) must be marked by an outer finish that is orange or by other effective means at every point of connection. White identifies the grounded conductor and green identifies equipment grounding, so neither can mark the high leg.
Law Reference: 2023 NEC §110.15Practice all 521 questions free — no signup required.
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