Multiple light fixtures on same circuit

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  #1  
Old 02-18-14, 11:07 PM
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Multiple light fixtures on same circuit

I currently have knob&tube (two 20A breakers) feeding:
  • overhead lighting in 2 bedrooms, dining room and bathroom
  • 3 wall sconces in living room and hallway
  • front outside light
  • single gfci in bathroom
  • wall mounted light in bathroom
I'd like to abandon it, replacing with 14/2 for the lighting and putting the bathroom gfci onto it's own 15A circuit (plus adding a second protected bathroom outlet).

Three questions:

1. What is the generally recommended way to chain multiple lights (each controlled by a single switch) on a single circuit? A couple of different ways come to mind:

- Chain together at each light fixture box. Run a length of 14/2 back to the controlling switch carrying the switched hot (black/white).

- Chain together at the controlling switch, 14/2 from the previous light fixture box to the next switch, 14/3 from the switch to it's light fixture box (carrying switched and unswitched hot)

2. The wall sconses have their own integrated twist switch at their base. Is it acceptable to mount a junction box above each (in the attic) and just run a single wire down to each sconse? Basically make a 'T' for each in the chained light circuit? The reason I ask is due to the available space in the legacy box behind each.

3. Is there a guideline on the maximum number of independently switched lights on a single circuit? I'm aware of the 80% rule but that ends up meaning I could pretty much run all on a single circuit. Also I'm not sure if the bathroom lighting needs to be separate?
 
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Old 02-19-14, 02:11 AM
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The newest code calls for a neutral at the switch location so you would need xx-3 for your switch loop.

The new bathroom receptacle needs to be on a 20 amp circuit with GFI protection wired with #12.
 
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Old 02-19-14, 04:27 AM
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The best way to wire up the multiple lights is to run power first to a switch box. From there switched power runs to the first light served by that switch. Additional lights served by the same switch are daisy chained (teed off) from the first light.

Raw power continues from the first switch box to switch boxes in different locations for different lights, or directly to light boxes for lights with twist switches or pull chain switches. Junction boxes for daisy chaining (with covers exposed in the room or the attic) may be used wherever needed befoer legacy light boxes or legacy switch boxes that are too small for daisy chaining.

The 20 amp circuit for the bathroom receptacle may also serve lights, fan, etc. in the same bathroom and nothing in other rooms or bathrooms. Or it may serve receptacles only in one or more bathrooms with different 15 or 20 amp circuits for lights, fans, etc.
 
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Old 02-19-14, 08:27 AM
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Originally Posted by pcboss
The newest code calls for a neutral at the switch location so you would need xx-3 for your switch loop.
When I say xx-2 I'm using the modern meaning of it (or at least what's on the package label) which is 2 wire (black/white) + ground. I was planning on running ground to the switch and assumed it was achievable using either of the methods I outlined in my original post.

Originally Posted by AllanJ
The best way to wire up the multiple lights is to run power first to a switch box. From there switched power runs to the first light served by that switch. Additional lights served by the same switch are daisy chained (teed off) from the first light.

Raw power continues from the first switch box to switch boxes in different locations for different lights, or directly to light boxes for lights with twist switches or pull chain switches.
What I don't like about this (I will do it if it's "best practice") is that it means 3 sets of 14/2 are going into each switch box, input, output to light fixture (switched) and output to next light switch (unswitched). This seems pretty crowded.

With my first example I'll have 3x 14/2 entering each light fixture box and 1x 14/2 entering each switch box but I've found the light switch boxes are a lot larger. With my second example I'll have 14/2+14/3 entering each switch box and 14/3+14/2 entering each light fixture.

Not trying to argue, just understand your reasoning.

Also, for this project it's 1:1 light-switch:light-fixture, i.e no switch controls more than one light and no light has more than one switch.
 
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Old 02-19-14, 12:45 PM
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- Chain together at each light fixture box. Run a length of 14/2 back to the controlling switch carrying the switched hot (black/white).
When I say xx-2 I'm using the modern meaning of it (or at least what's on the package label) which is 2 wire (black/white) + ground. I was planning on running ground to the switch
Yes, you need the ground to the switch, but you still need a neutral too. The neutral is not electrically necessary, but it's code required per the 2011 NEC. In your case, you would use the black and red wires for the switch loop and not connect the white neutral at all on either end, just add a small wire nut on each end.
 
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Old 02-19-14, 12:53 PM
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Originally Posted by CasualJoe
The neutral is not electrically necessary, but it's code required per the 2011 NEC ... not connect the white neutral at all on either end, just add a small wire nut on each end
Out of curiosity, what is the rational for this? As it obviously sounds a bit odd. If the neutral is capped at both ends there wouldn't seem any need for it.

Anyhow sounds like you advocate chaining through the light fixture boxes, rather than through the switch boxes as AllanJ suggested. Thanks!
 
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Old 02-19-14, 01:03 PM
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Out of curiosity, what is the rational for this? As it obviously sounds a bit odd. If the neutral is capped at both ends there wouldn't seem any need for it.
It's required by the 2011 NEC. Probably required in the event someonbe wants to add a timer or occupancy sensor that requires a neutral to operate. If your jurisdiction is still under the 2008 or earlier version of the NEC you don't have to do it and can use xx-2 NM-B cable.

Anyhow sounds like you advocate chaining through the light fixture boxes, rather than through the switch boxes as AllanJ suggested.
I just think it's quicker, easier and uses less material unless you are under the 2011 NEC.
 
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Old 02-19-14, 01:10 PM
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Once up on a time a timer or occupancy sensor could draw current through an incandescent bulb to power itself but that isn't true with CFLs or LEDs. Now with the government phasing out incandescent bulbs the neutral is now needed to future proof the switch box..
 
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Old 02-19-14, 02:05 PM
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Thanks for the rational. I'm going to pull a permit to do the work (I'm not going to lie on a property sale disclosure document). I checked with the city and as long as it's not a rental and I'm not selling in the next 12 months, I can do the work myself with a permit. I'll check on whether I can use xx-2 or if I have to use xx-3 but now I understand the rational I might just go ahead and use xx-3 to future-proof it.

I'd prefer to chain via the light fixture boxes also. Larger box, more room to make the connections. Thanks for confirming.

On a different topic, I asked earlier about the wall sconces and whether I could add a junction box above each and run a single wire down. Attached pics show why. The legacy iron boxes are going to be a pain to run two sets of wires into. It's going to be a pain anyhow, I need to see if I can pull new wire using the old but based on other areas of the house I'm expecting there to be a knob on the stud half way up the wall. Also due to the roof slope I may have to cut into the wall directly below the ceiling to drill up into the attic, depends on how the old knob&tube is routed. It's also an exterior wall so it's full of blown in cellulose (not great for k&t I know, the guys who blew it in told me all the k&t had been abandoned).

I'm already going to have to use one new box as I bought a sconce off eBay for the hallway to match the existing two in the living room. The old hallway sconce was mismatched/hideous and mounted about 2' too high on the hallway wall. I'm not much into burying boxes beneath plaster but I'm not coming up with a clean way to hide the box due to the narrowness of the slipper shade base.

Tips/suggestions welcomed. This is the only part of the project I'm expecting to be tricky.
 
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