Terminal guard for transformer secondary needed per NEC or NFPA79


Milwaukee WI
A transformer is fed from 2 legs of a 3-phase 480V, the secondary is 120V. The transformer comes with a guard for the 480 side but there is no guard given for the secondary. Would a guard for the secondary only be required if the unit was installed outside of an enclosure? My understanding is that the transformer is placed in an enclosure with other equipment the terminals of both primary and secondary could be left unguarded per NFPA 79 6.2.3. Is this correct?

Thank you!


Staff member
San Francisco Bay Area, CA, USA
Electrical Engineer
If the transformer is inside of a control panel, you do not need to guard the terminals, line or load. Some people choose to do so, but it is not a requirement. The only time the terminals must be "guarded", meaning inaccessible, is when the transformer is open, i.e. hanging on the outside of the box.