25ft Tap Rule for Transformer Question

[schicco]

My 225Kva transformer Primary-480V & 208V-Secondary is fed from a 350A breaker via (3) 500Kcmil; the transformer then feeds a panel that is located 15ft away via (2) 4#500Kcmil. I can't use the 10ft tap rule, so I am I OK with the 25ft tape rule? Please see attached. Everything is located inside a building.
Thanks a lot

Steve

 

[augie47]

The biggest problem I see is with 408.36. Once that is addressed, I don't see a problem with the 25ft tap rule.

 

[david luchini]

I see a big problem with 240.21(C)(6)(2)

 

[augie47]

I see a big problem with 240.21(C)(6)(2)

agree,,, but the 408.36 requirement for a main, once addressed, will automatically address that, yes ?

 

[david luchini]

agree,,, but the 408.36 requirement for a main, once addressed, will automatically address that, yes ?

Sure, but his question was about the "Tap" rule. As drawn, its a violation of 240.21(C).

 

[schicco]

Thanks a lot gentlemen.
David; could you please let me know what needs to be changed on DWG so as to comply with 240.21(C)

 

[ptonsparky]

Read on a little further. Three phase transformers need to have overcurrent protection for the secondary conductors.

You need a main breaker instead of a MLO, or else fusing/CB between it and the transformer.

 

[don_resqcapt19]

Also, for 800 amps on the secondary of a transformer you need two sets of 600 kcmil, 500 kcmil is not large enough for that application.

 

[schicco]

Thanks a lot to all of you for the advice, I really appreciate it.

Steve