Electrical Circuit Question

[sroxberg]

I am adding some lights to an existing circuit in my house and have some questions. I'm questioning the quality of the work performed by my fathers electrician from years ago, the town drunk of course.

The conduit is carrying three circuits, two 20 amp and one 15 amp.

The conduit is only carrying two neutral wires with one of them providing the neutral for one 15 amp and one 20 amp circuit. From what I can tell so far the neutral wire is at best 12G and possibly even 14G since one of the black wires leaving a 20 Amp circuit is currently 14G and one leaving the 15 Amp circuit is currently 12G, which I believe is incorrect and I may switch these after a complete diagram is mapped. Should I plan to add a separate neutral wire for each circuit which of course would be correctly sized to each breaker?

One of the circuits, I'm hoping the 15amp is running the light in the center of the room. This is where I'm planning to replace the existing 4 bulb fluorescent and add four new lights. The new lights are very low wattage LED flush mount ceiling and are rated at consuming 22 watts each, so is 110 Watts ok to run on a 15 amp circuit?

The light switch today is switching the neutral wire and not the black wire. I've seen diagrams both ways so I'm not sure which is appropriate or correct if there is such a thing. I'm guessing that he stitched the neutral wire for the light which allowed him to take a hot, neutral to the far side sockets which run on the same circuit today. Should I change this to switch the hot wire to the light or does it matter?

[blackhat]

First thing I would do is map every light and receptacle on each circuit. Is there any need for 20 amp circuits? Perhaps replace the breakers to those circuits and the 14 should be ok? I would pull another neutral and then you're not stuck with a tied handle breaker. Don't switch the hot, change that out. Your new fixtures will count as 4, that may exceed the permitted number on the circuit. A good map will be useful there.

[TDKPE]

I am adding some lights to an existing circuit in my house and have some questions. I'm questioning the quality of the work performed by my fathers electrician from years ago, the town drunk of course.

The conduit is carrying three circuits, two 20 amp and one 15 amp.

The conduit is only carrying two neutral wires with one of them providing the neutral for one 15 amp and one 20 amp circuit. From what I can tell so far the neutral wire is at best 12G and possibly even 14G since one of the black wires leaving a 20 Amp circuit is currently 14G and one leaving the 15 Amp circuit is currently 12G, which I believe is incorrect and I may switch these after a complete diagram is mapped. Should I plan to add a separate neutral wire for each circuit which of course would be correctly sized to each breaker?

It might be a multiwire branch circuit (MWBC), which shares a neutral, but both ungrounded (hot) conductors have to be on opposite poles in the panel, so the neutral only carries the current difference.  Do it wrong, and it will carry the neutral current for BOTH circuits, which is potentially twice what it should carry.  But two different ampacity circuits means the neutral has to be 12 gauge for the 20A circuit.  And it sounds like it's backwards.  As Blackhat suggested, do you need 20A on either?  More research is needed here.

One of the circuits, I'm hoping the 15amp is running the light in the center of the room. This is where I'm planning to replace the existing 4 bulb fluorescent and add four new lights. The new lights are very low wattage LED flush mount ceiling and are rated at consuming 22 watts each, so is 110 Watts ok to run on a 15 amp circuit?

Sure.  A 15A circuit is good to 1440 watts continuous, and lighting is considered (by the NEC) to be a continuous load.

The light switch today is switching the neutral wire and not the black wire. I've seen diagrams both ways so I'm not sure which is appropriate or correct if there is such a thing. I'm guessing that he stitched the neutral wire for the light which allowed him to take a hot, neutral to the far side sockets which run on the same circuit today. Should I change this to switch the hot wire to the light or does it matter?

Are you sure it's actually the neutral being switched, and not a hot switch leg?

[sroxberg]

I've researched the shared neutral wire enough to know that I will add a third neutral so that each circuit has a dedicated neutral. The breakers are not bonded together so that alone is a problem and since they also are not next to each other in the panel I'm not even sure if they are on different legs so better to just isolate each circuit.

The switch for the lights is switching the hot or black wire from the breaker and not the neutral. I will be rewiring the existing light and the new ones onto the 15 amp circuit already in the conduit so I can make the switch work on the neutral or the hot, but what is the accepted or normal way to do it?

So all outlets will be on a dedicated 20 amp circuit 

The lights will all be on a dedicated 15 amp circuit.

The third existing 20 amp circuit is running an air conditioner in the living room and that is currently dedicated to that.

So what about the switch, should I switch the neutral or the hot?

[TDKPE]

Do not switch the neutral. Never switch the neutral. Insulation color notwithstanding.

[Bob10]

switching the neutral is basically a boobie trap that more often than not startle someone at the least or really hurt someone possibly even yourself or loved ones.

[DaveinOhio]

I don't mean to come across as disrespectful, but your situation calls for an experienced residential electrician, given your level of expertise. You could get injured doing it yourself. People do some strange things in house wiring, that the code writers never anticipated.

That being said, good luck.

Dave

[JTTHECLOCKMAN]

How do you know it is a neutral. There is a little adage in the electrical world. A neutral is always white but a white is not always a neutral. The white wire could very well be the feed for the switch. You do not say what size pipe or I missed it so you have to be careful with capacity if you are adding wires. I would se if you find a sober electrician to help you out.