If I can add a point to the case for multiwire circuits.
Recently one of our electricans wired a large clothing store which had tons of incedescent recessed lighting. Upon completion we received a call that a panel was overheating. Our service man reported back that everything seems kosher with the conductor sizing and connections, yet he said the panel was extreamly hot. The panel controled all the stores lighting and was a 200 amp 3 phase, 42 circuit panelboard . All 42 circuits were fully loaded, yet with in allowed tolerances and all the conductors were very neatly tie wraped.
I was called in at this point to attend a meeting with the local inspector, engineer, and all others involved. While we were looking at this panel I noticed what seemed like an excessive amount of netural conductors. 42 to be exact.
I asked our electrican why seperate neturals ?
His response was because the engineer called for it on plans. Well common sense here, if all the circuits are loaded to 16 amps, then all the neturals are loaded to 16 amps. Which seemed like alot of fully loaded conductors tiewrapped together in the wireways of the panelboard.
I explained my theroy to the project engineer and inspector and they both agreed the amount of fully loaded conductors must be causing the excessive heat and that shared neturals would reduce the loaded conductors thereby reduce the heat build up.
Before the day was out, I had a signed change order to remove 2/3's of the neturals in the panelboard. Once the was done, no more heat. Problem solved.
So Seperate neturals do not always mean a better instalation.
