Junction Box

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TyB

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We installed a new 1000A 3P 208V service entry on the second floor of our building. The old service feed a 400A 3P disconnect on the first floor which then went into a junction box and spliced to feed a 225A 3P panel in the back of the 1st fl and a 100A 3P panel in the front of the 1st floor.

We are running a new 400A 3P circuit from the main panel on the 2nd fl to the 1st fl. Can we again enter a junction box on the 1st fl and splice to feed both the 225A and 100A panels? Assume that the conductor sizes are correct.
 
TyB said:
We installed a new 1000A 3P 208V service entry on the second floor of our building. The old service feed a 400A 3P disconnect on the first floor which then went into a junction box and spliced to feed a 225A 3P panel in the back of the 1st fl and a 100A 3P panel in the front of the 1st floor.

We are running a new 400A 3P circuit from the main panel on the 2nd fl to the 1st fl. Can we again enter a junction box on the 1st fl and splice to feed both the 225A and 100A panels? Assume that the conductor sizes are correct.
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do these conductors meet the tap conductor requirements?
 
The 225A and the 100A panels are sub panels with no main breaker. The 225A panel would be less than 10 ft from tap but the 100A would be approx. 100 ft away.

The junction would be new. It is not yet sized.
 
TyB said:
The 225A and the 100A panels are sub panels with no main breaker. The 225A panel would be less than 10 ft from tap but the 100A would be approx. 100 ft away.

The junction would be new. It is not yet sized.
Click to expand...

You need 400 amp conductors to each panel.
 
The conduit and conductor for the 100A sub panel that is 100 ft away from junction box is original so I would rather not redo that. Could we run the 400A main feeder to a splice in the JB with the 100A conductors leaving the splice and JB into a 100A disconnect before running 100 ft to the 100A sub panel? Also splice a 400A conductor to the 225A sub panel 10 ft. from the JB? Could we also include in the splice a feeder for an additional 100A panel next to the JB? All panels are 3 phase.

Would it be better/easier just to install a 400A 3P main breaker distribution panel on the first floor and feed the 225A and 100A subpanels with breakers from it?
 
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You have a few choices one is to just run full size conductors to each panel or another is to use the tap rules. For the 100 amp you could set a disconnect switch and run 100 amp conductors to it that are 10' or less tapped to the 400 amp conductors.
 
infinity said:
You have a few choices one is to just run full size conductors to each panel or another is to use the tap rules. For the 100 amp you could set a disconnect switch and run 100 amp conductors to it that are 10' or less tapped to the 400 amp conductors.
Click to expand...

In addition to the above, keep 408.36 in mind. Your panels need main breakers (or some overcurrent protection) either as part of the panel or ahead of the panel.
Your idea of a 400 amp subpanel might well be the best route.
 
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