2008 nec article 368.17

[grumpy11]

reducing a 4,000 amp bus duct to a 1,200 amp reducing fuse box 12ft to 15 ft high.

from 1,200 amp reducing fuse box we continue with conduit and wire.

the voltage is 480 volt.

something seem wrong with this installation.

 

[kenaslan]

Please restate your question it is unclear

 

[grumpy11]

can you install a 1,200 amp fuse reduceing box on a bus duct 12 to 15 ft high

what if one of the fuses blows you would need to shut the hole bus duct down to change the fuse.

 

[kenaslan]

The fuses should be in a disconnecting box you need to have some sort of disc before the fuse holders

 

[grumpy11]

thats the way i see it but the engineer says no

 

[fmtjfw]

plugin requires a switch

plugin requires a switch

368.17 Overcurrent Protection.
(C) Feeder or Branch Circuits. Where a busway is used
as a feeder, devices or plug-in connections for tapping off
feeder or branch circuits from the busway shall contain the
overcurrent devices required for the protection of the feeder
or branch circuits. The plug-in device shall consist of an
externally operable circuit breaker or an externally operable
fusible switch. Where such devices are mounted out of
reach and contain disconnecting means, suitable means
such as ropes, chains, or sticks shall be provided for operating
the disconnecting means from the floor.

Exception No. 1: As permitted in 240.21.

240.21 is the tap rules section


If the fuse box is not a bus plugin it is not clear from 240 that a fuse assembly must include a switch.

 

[grumpy11]

the bus duct we are taping from now feed chillers . we are just adding more load into the 4,000 amp bus. taping the bus putting this fuse rducer box then continueing on with conduit and wire.

i dont know it just seems an odd installation