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Discussion Starter · #1 ·
Good afternoon folks,

I’m an maintenance electrician working for a college system in NY, and have been tasked with changing out existing Obsolete light fixtures in the corridor s with new LEDs in a dormitory. Sorry for this huge message, but I have run into something I have not seen before and I am looking for some input.


The short story is I have found in all of the corridor lighting of The dorm. from 1st to 4th floor that there are 2 different sources of power feeding a split panel on the first floor(which feeds all the corridors), the top part of the split panel is fed from normal building power from a breaker on the switch gear and the bottom part of the split panel is fed from a 3 pole 50amp breaker in a separate emergency panel(transfers automatically upon power loss). A neutral from each feed is tied to a common neutral bar in the split panel. However I have noticed that in the corridors there is only 1 neutral wire being shared by 2 separate hots from 2 separate panels.

The longer version after some investigating;
It appears in the original build (1965)the split panel was all fed from a single 3 pole breaker and just changed which lights were on at night vs the day time for dimming by flip flopping the upper and lower split panel using 2 contactors (each feeding 1/2 the panel)and a timer, at that time there was no generator or emergency panel. Sometime in the 1980s a generator was added and the bottom part of the split panel was converted to the corridor emergency lighting panel(and night lights) and the upper panel remained fed from the main switch gear. It looks like there is a neutral from each separate feed that is tied to a common neutral bar in the split panel, and both neutrals are well below the current that may cause overload concerns (6 amps daylight and 3 amps emergency). However there is only 1 neutral wire feeding from light to light, every other light is currently an emergency light (and night lights) and the others are fed separately for day lights and not on the generator.

My question is, does it meet code to have the lighting conductors fed from 2 different sub panels wired to share a single common neutral, and what sections of the NEC should I refer to for this particular situation. If this does not meet code, what kind of priority should we consider this? Should each section of the split panel have its own neutral bar then feeding out to the appropriate fixtures from that ? should we bring additional neutrals in ASAP.?
 

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Bring in a j-man electrician. You're dealing with a hair-ball.

Your position is to REPAIR and maintain not engage in electrical reconstruction of an antique build.
 

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Old Grumpy Bastard
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Welcome aboard @Jpasco!

I'm sure you are very concerned with all of this and while I think you should bring it up to your supervisor 'if it ain't broke don't fix it'.

If it was going to blow it would have happened a long while back.

Love to know what place this is because i recall a SUNY dorm building I did some alarm work in that had some "in home fixes" by former maintenance staffing.

Enjoy your ride here bro!
 

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Discussion Starter · #4 ·
ha....this work was supposedly done by a contract electrician in the 80s.....out of a nearby IBEW local. ...there are many cob artist around including long time j...men....ive worked with a few over 20 years. knowing how to fix it isn’t really my question, my question is it a code violation if so which section did you find it in and is it important enough to fix while i am already removing every single light anyway....
 

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The neutral must be run in the same conduit, or path as the hots.

I have seen 1 where someone ran the neutral in a separate EMT from the phase conductors. I'm sure it's still there... and working.
 

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Bring in a j-man electrician. You're dealing with a hair-ball.

Your position is to REPAIR and maintain not engage in electrical reconstruction of an antique build.
You have never worked as a maintenance electrician in the south. We do it all down here.
Run conduit. Pull wire. Wire new additions along with the equipment and the processes. And the occasional plugged up toilet.
 

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You need to sketch the wiring diagram and post it.

It was common for 1 neutral to be used by 2 different breakers on lights as some are switched while others stay on all the time. Back in the 80's it wouldn't have been a problem to have the breakers in 2 different sub panels (or split buss) especially as one is technically a transfer switch panel (all neutrals would have been joined before the meter).

Unless you understand how it was done and the thought behind it (how did they size the neutrals) then you could make a real mess thinking you are doing a upgrade.

With LED lights and a good plan theirs probably no need to worry about load shedding some of the light.
 
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