*
I have reached the wiring stage of my modest addition, and am unsure as to the allowable number of light fixtures on a 15 amp circuit. Can someone help me out? Can a 20 amp circuit be used for lighting, with a jump to 12 gauge wire?
Thanks
*
I have reached the wiring stage of my modest addition, and am unsure as to the allowable number of light fixtures on a 15 amp circuit. Can someone help me out? Can a 20 amp circuit be used for lighting, with a jump to 12 gauge wire?
Thanks
Michael Hindle explores the efficacy of deep energy retrofits and discusses essential considerations for effective climate mitigation.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Get home building tips, offers, and expert advice in your inbox
Fine Homebuilding
Get home building tips, offers, and expert advice in your inbox
© 2024 Active Interest Media. All rights reserved.
Get home building tips, offers, and expert advice in your inbox
Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.
Start Your Free TrialStart your subscription today and save up to 81%
SubscribeGet complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.
Already a member? Log in
Replies
*
In northern Illinois, the number of "openings" (read light fixtures in your case) is 8 for a 15 amp circuit (14 AWG NMC w/ground and a 15 amp breaker) or 10 for a 20 amp circuit (12 AWG w/ground and a 20 amp breaker). I could not find this specifically spelled out in the NEC which is not the easiest reading in the world but the local electrical inspector had a summary sheet for specific items that are required.
Don't forget phone/cable/security/etc wiring. Have your wife or other people check to see if you have enough switches, outlets and are in the best locations because now is the time to change it. Ohm out the circuit(s) before the sheetrock goes up. What seems obvious now gets real obscure when you can no longer see where the wires run. Sketch a circuit diagram showing which box the power comes into and then the routing of the wires from box to box. You may not use it but if you need it, it is incredibly frustrating to try to remember how (exactly) you ran the wires.
Good luck
*> Ohm out the circuit(s) before the sheetrock goes up.Al,What does this mean? Or is it just clever phrasing for the mapping that you describe.Thanks,Rich Beckman
*The NEC actually allows 10 receptacles per 15A breaker and 13 for a 20A (section 220-3). Having said that, less is always better then more. If you are trying to get by with just one circuit in the room, I would suggest that you at least put your lighting circuit on a different line. This allows you to do electrical work in the room without being in the dark.The NEC requires you to have a minimum of power in the room equal to 3 watts per square foot (including lights). To figure out your required load, divide you square footage by 120(volts) and that will give you the required amps for the room. Put in multiples of 15 and 20 amp breakers to reach that level.Finally the NEC also requires a receptacle within 6' of every point on the wall. That is you should be able to place a lamp with a 6' cord, anywhere along the wall and be able to plug it in without an extension cord. Add extra outlets beyond this for (as Al says) any extra requiments (TV, VCR, Stereo, etc.)
*Actually the NEC does not have any limit on the number of outlet per circuit for a dewelling.As to the number of lights on a circuit then you should use the rating of the lighting devices and you only want to load the circuit to 75% of rating.Yes, you can use a 20 amp circuit. However, as the light circuit often have 3 way and 4 way switches, and boxes with mulitple switches some people like to stay with 15 amp/ #14 circuits as they are easier to wire.
*How do I calculate the number of light fixtures on a 15 amp circuit (lighting only)? I.e. 75% of what? Do be even more specific how is the 15 amp circuit rated (watts?) and what is the rating number?Thanks.
*SteveA 15 amp circuit can supply 1800 watts (15 x 120 volts). 75% of that is 1350 watts.Then look at the lighting fixtures. It will have a label indicating the maximum size of bulb that it can use (example 100 watts or 2 75 watt bulbs). Add all of those up until you get to 1350.
*Steve --15 Amps X 120 Volts = 1800 Watts. 1800 Watts X 75% = 1350 Watts. 14 gauge wire is limited to 15 Amps.20 Amps X 120 Volts = 2400 Watts. 2400 Watts X 75% = 1800 Watts. 12 gauge wire is limited to 20 Amps.Personally, I use #12 for everything except the dedicated smoke detector circuit. I don't find it physically more difficult to pull or bend by enough to be concerned about. The only downside to #12 is that you reach the box and conduit fill limits quicker. So, use the biggest boxes you can, 4 11/16", and you'll probably be OK. Big boxes do make the work easier. Oh, and BTW, I try to keep the number of lights on a circuit under ten. But that's just me. And I try to "leapfrog" which lights are on which circuits, so if the breaker pops for the light in one room, you can still see to walk around by the light spilling in from adjacent rooms or hallways. Wire is cheap, so put in plenty while you have the chance.-- J.S.
*If you run all your lights on 20 amp circuits you have to upgrade your switches to ones rated for 20 amps as well. Around here a cheap 20 amp is $2.50 vs. less than a dollar for a 15 amp. Of course I could be wrong about this because I see switches and outlets rated for 15 amps on 20 amp circuits all the time. Is this truly dangerous? I always encourage homeowners to switch thiese out but most seem to resist.
*E --It's perfectly OK and quite common to have 15 amp rated switches and receptacles on 20 amp circuits. The only time NEC requires you to go up to the 20 amp receptacle is if it's the only thing on the circuit, like with the dedicated laundry circuit. You need the 20 amp switch rather than the 15 amp one only if the load controlled by that switch is over 15 amps.This is fundamentally different from the way it is with wire. You can't ever put any 14 gauge wire anywhere in a building on a 20 amp circuit. (But you can plug in an extension cord of 14, 16, or even 18 gauge on any circuit.)-- J.S.
*Looking at the posts. There appears to be errors in what the code requires (most of it simply good practice).For a residence there are very few requirements and they apply to kitchen related rooms (20amp circuits), and bathrooms (GFCI circuits).For light circuits 13 (18) 100w lights (with or without ceiling fans) will not trip a 15 (20) amp cicuit. If you have space, use 2 circuits so you will still have some lights if one circuit needs repairs.By the way I like to use a separate circuit for each room's recepticles. (What was my kid's bedroom now has 4 computers and 2 lasar printers.)
*Browse through this and bookmark it for future reference:http://www.codecheck.com/numberoutlets.htm
*Just where in the world are ya? In Canada you can load a breaker to 75% of it's rating.....15 amp breaker = 12.5 amp load. Each device (light or plug)counts as 1, because you can't have .5 of a device you are allowed 12 devices per circuit. I never run a circuit for plugs only or lights only, usually they are shared. Use common sense here, if you are going to load up a plug with some heating type load keep that circuit lite.
*I have a related question. I am putting in new wiring in my old (1900) house and adding outlets in each room. I have tall (9 inch") baseboard and would like to mount the outlets in them, primarily for aesthetics, but also to avoid cutting into plaster. There are already a few outlets mounted in them.My question is, what does the code say on this? Is it acceptable? I really, really don't want to put them in the walls. I have been to the library and bookstore but couldn't find a DEFINITIVE answer. Any suggestions?
*.
*In chicago the electrical inspector had me change all of the 20 amp breakers that served lighting to 15 amp breakers. All of the wire was 12 ga.. The inspector stated light fixtures are not designed for a 20 amp load.
*i The inspector stated light fixtures are not designed for a 20 amp load. They ain't designed for a 15 amp load either.You are fortunate that he did not look at the lighting fixtures and see that they they where rated for a max of 100 watts and make you use a 1 amp breaker.
*AJ must be skiing or hang-gliding out of town... :)(if you're a casual reader, sorry, that's an inside joke)
*Dirk,There's nothing in the NEC prohibiting you from placing receptacles in your baseboards. If you're concerned about the height off of the floor, that's a design consideration that the Code doesn't address. Put them in diagonallly half-way up the wall if you want to, they'll still be safe as long as you use an appropriate box that ends up flush with the finished combustible surface.
*Thanks, I appreciate it. I was hoping the 12 - 18" was a standard practice, not a rule, and your info leads me to believe that is the case. I can't see why being in the baseboard would cause any problem, and it will certainly look better.
*Dirk - it's 'standard' for most of our work, especially historic houses. Jeff
*Dirk --If your house is like mine, the bad news is that there's plaster behind the baseboards, so you'll be cutting into plaster no matter what you do. My favorite trick is to use a diamond blade hand grout saw from the tile shop. For just one or two, it's easier to do them by hand than to change the Makita to the diamond blade. If I do use the Makita, I still use the hand saw to clean up the corners. Done carefully, you can make exactly the hole you need with no need for patching plaster other than the small exploratory stud finding holes.-- J.S.
*John, yes, there is plaster behind the baseboard, but when it's patched it will be hidden again. I may even use drywall to do the patching and am considering putting in firestops if none exist. Also, I think it will be easier to run the power to the next outlet horizontally. Again, this is primarily for cosmetic reasons as I think the baseboard outlets will be less obtrusive; I plan to use dark outlets with bronze covers.The thing I'm wondering now is attaching the conduit. If I mount the outlet boxes 2 or 3" above the floor it wont be anchored again for another 9 feet, when it reaches the ceiling joist. I realize that it doesn't have to be done in conduit, but there are outside influences that dictate doing so.
*
I have reached the wiring stage of my modest addition, and am unsure as to the allowable number of light fixtures on a 15 amp circuit. Can someone help me out? Can a 20 amp circuit be used for lighting, with a jump to 12 gauge wire?
Thanks