#bus #transformer 3 phase 210.71 310.15 afci annex d arc flash bonding cable circuit breaker closed delta conduits current delta design disconnect disconnect switch duct bank equipotential bonding etap evse fault feeder flat rate general electric generator gfci gfi ground grounding grounding and bonding high leg hvac induction motor induction motors labeling lfmc lighting load calculation low voltage ltc medium voltage motor motor control center motor starter panel nec nec 2017 ocpd open delta outside branch circuits pricing pvc raceway relay service service calculation services short circuit short circuit calculation siemens sizing switchgear test x/r transformer ul508a ups vfd wire nuts working space