joulesarecool
Member
Existing switchboard has a 1200A busduct off the main switchboard rising up the floors of an office building. At the 6th floor, it transitions up to the top with 600A. Thanks!
Code violation?: 1200A busduct transitioning to 600A
- Thread starter joulesarecool
- Start date
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
How old is the installation, what code was in effect?
How long is the 600A run?
The 2005 NEC 368.17(B) would not allow this in a non-industrial installation.
How long is the 600A run?
The 2005 NEC 368.17(B) would not allow this in a non-industrial installation.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: Code violation?: 1200A busduct transitioning to 600A
how is this any different than any other tap?
joulesarecool said:
how is this any different than any other tap?
bdarnell
Senior Member
- Location
- Indianapolis, IN
- Occupation
- Retired Engineer
Re: Code violation?: 1200A busduct transitioning to 600A
It's different in that it's specifically addressed in Article 368. The requirement goes back as far as the '99 Code, at least that's the oldest one I have with me.
joulesarecool said:
petersonra said:
It's different in that it's specifically addressed in Article 368. The requirement goes back as far as the '99 Code, at least that's the oldest one I have with me.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: Code violation?: 1200A busduct transitioning to 600A
my question was more along the lines of why is this requirement there? why does this type of tap require an OCPD and a tap using regular conductors does not? it does not appear there is any extra risk.
bdarnell said:
my question was more along the lines of why is this requirement there? why does this type of tap require an OCPD and a tap using regular conductors does not? it does not appear there is any extra risk.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Another 240.21(E) code reference is another location that says busway taps are special.
My guess is, it is because plug-in busways are not much different than very long panelboards. Would you allow a 600A MLO panelboard to be fed from a 1200A feeder?
My guess is, it is because plug-in busways are not much different than very long panelboards. Would you allow a 600A MLO panelboard to be fed from a 1200A feeder?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
jim dungar said:
again, i would ask, why would the 600A MLO PB be at more risk than any similar tap?
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