I design controls for custom equipment where typically 480vac is brought into the enclosure and then stepped down from there to power items in the enclosure. We feed the 480vac through a panel mounted disconnect with the disconnect handle located on the outside of the enclosure. If the disconnect is "on" the disconnect handle has to be defeated in order to open the enclosure. The job I am working on now we are bringing in 120vac into the enclosure. Does the disconnect have to be done the same way at this voltage level?
Enclosure safety
- Thread starter ayates
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Buck Parrish
Senior Member
- Location
- NC & IN
I would say no for 120 volts. But,
I think you need some thing they call the UL White book.
I think you need some thing they call the UL White book.
petersonra
Senior Member
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- Northern illinois
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- engineer
I am pretty sure there is no such requirement, regardless of the voltage.
- Location
- Wisconsin
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- PE (Retired) - Power Systems
Are you bringing in 120V in addition to or instead of the 480V?
Buck Parrish
Senior Member
- Location
- NC & IN
The way I read it. It is instead of '
I am bringing in 120vac and nothing else
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I know of no general requirement (except in NFPA 79) that any enclosure must have an integral externally operated disconnect to remove all power.
This is usually a requirement in keeping with NFPA79 for industrial machinery.
See NFPA79:2007 6.2.3 Enclosure Interlocking
Voltage levels are at or above 50vac (rms) or 60vdc.
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