NMC-B cable has a voltage rating of 600V.

The rated voltage for a cable is the voltage for which a cable is designed and defines the electrical testing requirements.

The rated voltage is expressed as the ratio of two values, U0/U, where U0 is the effective value (root mean square or r.m.s.) of the voltage between any insulated conductor and the “ground” (metal covering of the cable or surrounding medium). U is the effective value (r.m.s.) between any two-phase conductors of a multi-conductor cable or system of single conductor cables.

In an alternating current (AC) system, the rated voltage of a cable should be at least equal to the nominal voltage given by the U0/U value. In direct current (DC) system, the rated voltage of the system should be no higher than 1.5 times that of the nominal voltage of the cable.

Read *NFPA's* electrical safety tips to learn how to protect your family and home from electrical fires.