Splitting up dwelling branch circuits

[Jpflex]

When considering as the NEC describes “lighting and general use receptacle” branch circuits, I was wandering if it is common practice to share room lighting with receptacle lighting

I can see this going both ways. A contractor may want to save money by sharing ceiling switched lights with wall 20i amper cercuit power on the same branch circuit supply. However, due to tap rules, this arrangement would require the lighting circuit to have larger conductors such as NM 12-2 Romex switch legs and conductors instead of smaller 14-2 NM romex but will illuminate extra “home runs”

The other option is to keep lighting and receptacle on separate circuits such as receptacles on 20i NM 12-2 circuits and lighting on its own circuit using smaller NM 14-2 but the lighting circuits will require their own feeder run and likely will not come close to loading up a 15 ampere circuit to 12 amperes unless all lighting were done on one 15i branch circuit with LEDs at a fraction of an ampere each

Thoughts?

 

[infinity]

When considering as the NEC describes “lighting and general use receptacle” branch circuits, I was wandering if it is common practice to share room lighting with receptacle lighting

I can see this going both ways. A contractor may want to save money by sharing ceiling switched lights with wall 20i amper cercuit power on the same branch circuit supply. However, due to tap rules, this arrangement would require the lighting circuit to have larger conductors such as NM 12-2 Romex switch legs and conductors instead of smaller 14-2 NM romex but will illuminate extra “home runs”

The other option is to keep lighting and receptacle on separate circuits such as receptacles on 20i NM 12-2 circuits and lighting on its own circuit using smaller NM 14-2 but the lighting circuits will require their own feeder run and likely will not come close to loading up a 15 ampere circuit to 12 amperes unless all lighting were done on one 15i branch circuit with LEDs at a fraction of an ampere each

Thoughts?

If you really want to use 20 amp receptacle circuits then using 15 amp circuits for lighting is how I would do it. Back when a circuit breaker was 5 bucks we would run a single 15 amp circuit to each room and used it for both lighting and power. Now with AFCI's I would load the circuits up to the max. With LED's you could probably do the whole house with one 15 amp lighting circuit.

 

[Jpflex]

If you really want to use 20 amp receptacle circuits then using 15 amp circuits for lighting is how I would do it. Back when a circuit breaker was 5 bucks we would run a single 15 amp circuit to each room and used it for both lighting and power. Now with AFCI's I would load the circuits up to the max. With LED's you could probably do the whole house with one 15 amp lighting circuit.

Yea those are some things I was thinking but I didn’t know if others were using a single white 15i romex 14-2 for the entire lighting.

I was wandering if some were violating code by wiring receptacle outlets with 20 ampere 12-2 and then splicing into gang boxes with a 14-2 romes to supply lighting.

 

[Jpflex]

With LED's you could probably do the whole house with one 15 amp lighting circuit.

Also something to note is that although LEDs are more efficient and consume less power, using them apparently will disqualify you from applying an additional demand rating of 70% on your neutral ungrounded conductor size for service neutral conductors over 200i amperes. This means a larger neutral service / feeder wire.

 

[infinity]

I was wandering if some were violating code by wiring receptacle outlets with 20 ampere 12-2 and then splicing into gang boxes with a 14-2 romes to supply lighting.

No you can use 12/2 and 14/2 on the same circuit you would just need to use a 15 amp OCPD not a 20 amp.

 

[Choice_Gorilla]

Also something to note is that although LEDs are more efficient and consume less power, using them apparently will disqualify you from applying an additional demand rating of 70% on your neutral ungrounded conductor size for service neutral conductors over 200i amperes. This means a larger neutral service / feeder wire.

Isn’t that additional 70% just for the portion of the unbalanced load that exceeds 200 amps? For example if your calculated neutral load was 250 amps you could derate 50 amps by 70%? I don’t see it making enough of an impact on a residential service to consider not using LED lights.

 

[LarryFine]

It really is a design choice, but I prefer separate 15a lighting and 20a receptacle circuits.

Turn on all of the lights so you can vacuum, and then turn on the vacuum cleaner. Poof!

 

[augie47]

I always preferred to put my lighting on a #14. To me there's an advantage on box fill (especially with 3 way & 4 way) and I find terminations easier on #14.

 

[James L]

It depends on the application.

Recently wired a fourplex in a retirement community. Retirement people are older. Any of them will have an oxygen concentrator, and many of them like to have space heaters because they get a little chilly. Because of those factors, I wired all the receptacles on 20 amp circuits and ran one lighting circuit per unit.

Just a run of the mill new home, I don't separate out any rooms to be dedicated, and I don't keep lights separate from receptacles. The easiest way I can have 10-12 openings on a circuit, that's the way I'm going to wire it.

 

[Fred B]

Warning about mixing wire sizes. Seen too many times resulting of mixed wire size an oversized breaker being applied on a circuit that started our with #12 and a 20A breaker that along the way some splice to a smaller #14 was made but no change to breaker size. That would be a violation and dangerous with potential to damage of the smaller wire. What starts as a simple panel change with like for like on the breakers, and some small changes request "oh while you're at it can you change the switch from a togggle to the flat ones?" only to find a 20A breaker and the lights on #14.

Also agree with Augie that #14 way easier to handle in the small space of a fixture or switch box especially the small flat Canless LED. Usually end up cursing out the GC that ran the #12 and then ask you to hookup the lighting with a bunch of the canless.
Myself I exclusively run #14 for lighting and #12 for basic receptacles. It also save more money (#14NM $0.33/ft #12NM $0.46/ft) than would be using all #12 and trying remember "now which one and how many of the yellow has to be 15A?", and the cost of a 15A or 20A breaker is identicle.
Also get in and out of roughin inspections quicker that the inspector sees all white rope for light and yellow rope for recepticles.

 

[infinity]

Also agree with Augie that #14 way easier to handle in the small space of a fixture or switch box especially the small flat Canless LED.

I agree, with canless lighting I would use #14 and a 15 amp circuit. Given that these things draw only about 0.1 amp you could put the entire house on one circuit.