Have a 1200A 480V service board in dedicated electrical room. Would like to tap bus and extend conductors via conduit out top of said board across ceiling and terminate into fused SE rated disconnect switch. Installation would meet depth of working clearance and 25' tap rule. Concern is art. 230.70. Is this code legal?
110.3(B) can bite you in the butt. If you modify the bus in the field, the UL Listing is no longer valid; even if the manufacturer blesses your method. If you decide to go ahead, you should plan on paying UL for a field inspection to certify that the board retains its UL Listing. Otherwise the AHJ can turn down the whole job.
Good luck. You gents are on the ball. I am seeing more and more non-listed equipment, fixtures and devices out in the field and some contractors have been hurt badly by basing their bids on equipment that they can’t use. Some time a real bargain can cost you more than what you were planning to save in the first place. Regards, Elec N Spec