Temp Riser

[JoeStillman]

Where is this tap rule in NEC

240.21

 

[ramsy]

Where is this tap rule in NEC

No tap rules with 1/0 AL in parallel per 310.10(G), which fit100A lugs better than #500.

 

[Strathead]

Where is this tap rule in NEC

Joe said, but my warning. Be careful. it isn't one rule it is a lot of them and they are a little complex until you understand them

 

[augie47]

FYI: The tap rule comes into play when the conductor can carry the load but is protected by a breaker with a higher than the ampacity of the conductor. Because you have 100 amp breakers in your panel you need a 100 amp conductor supplying the panel but your feeder is 400 amps,.
The tap rules (240.21) allow you to use that 100 amp conductor being protected by the 400 amp breaker under specific conditions such as length of conductor, termination requirements, etc.

 

[ramsy]

SB is splice box.

No splice boxes needed with 1/0 serving 2 floors beyond switch gear, double lugs at 100A panels.

Using 100A main breaker panels protects 1/0 feeders at their ampacity.

 

[ramsy]

assuming each panel may drawing 80A.

If manpower is limited to working 1 or 2 levels at a time, a single-conductor feeder can daisy chain all main-breaker panels together.

 

[Alwayslearningelec]

So if each panel calc load was 50A @ 120/208v and I had 8 panels as shown I would need 400A.

I could run (2) sets of 4/0. One set feeding 4 panels and the other set the other 4. I can't terminate the 4/0 directly in the panel can I?

 

[infinity]

So if each panel calc load was 50A @ 120/208v and I had 8 panels as shown I would need 400A.

I could run (2) sets of 4/0. One set feeding 4 panels and the other set the other 4. I can't terminate the 4/0 directly in the panel can I?

Unlikely that a 100 amp breaker would accept a #4/0. Using two #4/0 risers would also work as long as you have two 200 amp breakers at the origin of the feeder.

 

[Alwayslearningelec]

Maybe I'll just figure 50-60A circuits to each 100A temp panel individually and let field figure it out if we get the job.
Maybe even be able to feed them with romex depending on size I need after voltage drop for further ones but I may get into trouble figuring 50-60A circuits because if the wind up using 100A I'm screwed.

 

[ramsy]

Maybe even be able to feed them with romex

Romex Monkeys are not allowed in 8-story buildings.
Temporary spider boxes run SO cord directly to sub-panels.

if the wind up using 100A I'm screwed.

Check plans for structural-steal welding.

 

[infinity]

Romex Monkeys are not allowed in 8-story buildings

NM cable is permitted in an 8 story building for temporary wiring.