Feed Thru Lug Panel

[dav5y]

Hi All,

I have a question, If I have a 400 amp riser feeding 225amp (main bkr) w/ feed thru lugs panels on the basement, first and second floors. Does the bus rating for the 225amp panels need to be 400 Amps ???? Im trying to avoid trough w/ a tap to the panel.......

 

[infinity]

If the bus is on the load side of the 225 amp CB then it only needs to have a minimum rating of 225 amps.

 

[dav5y]

Thank you..... One more question tho... The lugs would have to be rated for 400 amps ????

 

[GoldDigger]

Thank you..... One more question tho... The lugs would have to be rated for 400 amps ????

Yes and no. To the extent that the lugs actually carry the feed-through current. At least up to the next-to-last panel.
The connections to the wires have to be able to carry the full current safely.

 

[Glennsparky]

The lugs also have to be listed for the size and material of the wire.

If all the panels are daisy chained off the first panel and the the first panel has a 225A main breaker, then it's not a 400A riser. It's a 225A riser.

 

[Glennsparky]

You could "drop off" amperage at each floor. Do a load calculation for each floor. Let's say it came to 100A per floor.

The first panel would have a 400A MB, 400A busses and 400A feed thru lugs. The second panel could have 300A ratings for MB, busses and FT lugs. The third panel 200A and so on.

In my example, you may even be able to use the tap rules and use 300A wire and lugs between the 400A panel and the 300A panel. And so on down the chain.