AnsweredAssumed Answered

Per Art. 220.18 (A) three 17 amps motors can be feed from one circuit breaker (CB). Size of CB is 1.25 times largest motor load + other motors or 1.25 x 17 +17+17 = 55 amps or 60 amp CB in this example. However the VFD equipment manufacturer I am working

Question asked by Leo Eden on Oct 20, 2016
Latest reply on Oct 22, 2016 by Joseph Hren

Per Art. 220.18 (A) three 17 amps motors can be feed from one circuit breaker (CB). Size of CB is 1.25 times largest motor load + other motors or 1.25 x 17 +17+17 = 55 amps or 60 amp CB in this example. However the VFD equipment manufacturer I am working with says the three panel VFD requires an 80 amp CB according to UL508? Does anyone know why UL508 is requiring a larger CB?

Should I assume UL508 will supersede NFPA 70 on this subject?

Outcomes