Electrical clearances.

§ 18.24 Electrical clearances. Minimum clearances between uninsulated electrical conductor surfaces, or between uninsulated conductor surfaces and grounded metal surfaces, within the enclosure shall be as follows: Minimum Clearances Between Uninsulated Surfaces Phase-to-Phase Voltage (rms) Clearances (inches) Phase-to-Phase Phase-to-Ground or Control Circuit 0 to 250 0.25 0.25 251 to 600 0.28 0.25 601 to 1000 0.61 0.25 1001 to 2400 1.4 0.6 2401 to 4160 3.0 1.4 [57 FR 61209, Dec. 23, 1992]