220.4A and 300.3B applied to neutral bar mounted in overhead wireway.
First of, let me start by saying I am not young. I may have been lead into some possibly non complying practices over the last 50 YEARS which is WHY i ASK QUESTIONS.
The SCENARIO IS A 480/277V PANELBOARD WITH 3 2" CONDUITS EXTENDING VERTiCALLY ABOUT 40" into a A 10 X 10 X 48" WIREWAY WHICH is attached up tight to the finish ceiling. Now, in the past, we always considered that assembly as one big panelboard and once the cable conductors entered that wireway, one could pretty much do what one wants with them...i,e, install a grounding bar in the wireway to run all the branch circuit grounding conductors and so the same thing with an isolated neutral bar which saves counts on the conductor fill of the 40" 2' pipe to minimize conductor derating.
I have been doing it this way for well over 20 years until today when I was inspected by the senior state of Maine electrical Inspector. He states that 220.4A and 300.3b prohibit doing that and all the individual neutral conductors associated with each branch circuit must go all the way to the grounded terminal in the main feeder panel.
Does anyone smart out there have an opinion on this?. At one time, the State of Maine electrician's examaining board had issued an adoption stating that they would consider all electrical equipment on the same backboard as the feeder panel part of that FEEDER PANEL AND ONE COULD INSTALL THE NEUTRAL BAR WHEREVER ONE WISHED AS IT WAS NOW IN THE PANELBOARD ASSEMBLY.[
Last edited by mgawat; 07/29/19 06:09 PM.