I have a “switch control panel” composed of three 800A switches served by an 800A incoming feeder, but one switch will serve only a 400A load. The switches are interlocked so only one can be closed at a time. Can the size of the feeder serving the 400A load be reduced according to a tap rule, provided it is terminated in an appropriately sized fused disconnect?
Can I use a tap rule?
- Thread starter Pdan
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
I don't see why not if you meet all the requirements for making such a tap.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I don't see why not!
Edit: haha Peterson beat me by a few seconds, that rascal.
Edit: haha Peterson beat me by a few seconds, that rascal.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
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- Electrician
LOL, 2 seconds. Type faster!!!!!
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Do the other two feeds hit an OCPD or go directly to the load? If the latter, you have an interesting situation where the conductors feeding the switch panel change from feeder to branch circuit with the flick of a switch.
Thanks for the response(s) and the interesting observation.
Actually I simplified the configuration in the initial question. This switch control panel is feeding a crane conductor bar which is made up of some short isolating sections that can accommodate only one crane and longer sections that can fit up to three. There are other panels feeding the other sections of conductor bars, but this one feeds 1 long section and 1 short section.
The panel is fed by an 800A feeder that is connected directly to an 800A incoming switch. The output of the switch is tied to a bus that has 3 additional connections. One goes to the 800A conductors feeding the long section of bus, the second goes to an 800A switch to ground (for maintenance), and the third goes to an 800A switch with conductors going to the short section of conductor bar. We would like to reduce the size of the cables going to the short section of bar. We’re installing fused switches at the conductor bars.
Actually I simplified the configuration in the initial question. This switch control panel is feeding a crane conductor bar which is made up of some short isolating sections that can accommodate only one crane and longer sections that can fit up to three. There are other panels feeding the other sections of conductor bars, but this one feeds 1 long section and 1 short section.
The panel is fed by an 800A feeder that is connected directly to an 800A incoming switch. The output of the switch is tied to a bus that has 3 additional connections. One goes to the 800A conductors feeding the long section of bus, the second goes to an 800A switch to ground (for maintenance), and the third goes to an 800A switch with conductors going to the short section of conductor bar. We would like to reduce the size of the cables going to the short section of bar. We’re installing fused switches at the conductor bars.
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