GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Lights will be on their own circuit, separate from receptacles, size breaker for lights?

derekr | Posted in General Questions on

Since my lights will be on their own breakers should I go with a really low amp breaker like 10 or 5 amps? Or should I stay with 15?

all my lighting is led so I don’t think I’ll even be using 1 amp in the bedrooms even if ever changed them to regular 60 watt lights most of the rooms would still be under 3 amps for the light circuits

i don’t know if that’s a risk of not tripping the breaker if something goes wrong, all the wiring for the lights is 14 gauge

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. DC_Contrarian | | #1

    15 is the minimum allowed.

    1. derekr | | #2

      Ok thanks, guess it’s safe then

  2. Expert Member
    Akos | | #3

    You generally put most of the lights on a single circuit, not a circuit for each bedroom light. If the circuit is only supplying lighting with known power usage you can go for more than 12 devices per circuit as long as you don't exceed 80% capacity of the breaker. 15A*120V*0.8= 1440VA, so that is ~100 12W slim LED lights.

    1. derekr | | #4

      Well a lot of the breakers have 6-8 lights on them but some only have 4-6 just because of the location

      Some of them that if I connected them to other lights it would be over 200 feet on 1 line maybe even 300

      Even if I put half the lights on 1 circuit it would still be way below the max of the 15 amp breaker
      Actually even if I put every light in the house on 1 breaker it would still be way below 15 amp breaker
      I have 45 led lights all together each one uses 10 watts so that would only be 450 watts if every single one was turned on, if anyone ever replaced those with 60 watt lights though that would be a problem

      So idk what to do here, is it safe either way to have a breaker for each room vs having all the lights in the house on 1 breaker? Either way I do it it’s way below the max of a 15 amp breaker

      1. Expert Member
        Akos | | #5

        If those 10W LEDs are hard wired units where the LED element is not replaceable by non OEM units than you can put all 45 of them on a single circuit. If on the other hand it is canned pot lights with a E26 or GU10 base than it is a different story. Since with those you can replace the bulbs with higher wattage, you are back to the 12 device limit.

        Sometimes having multiple runs is simpler and and extra regular 15A breaker is pretty cheap. Where the cost starts really adding up is with outlets, AFCIs breakers are spendy.

        1. derekr | | #6

          Yea it is alot simpler to have a breaker for each room from what I’ve done so far, plus I like the organization of having a label for each room

          But with appliances I guess you’re not supposed to oversize your breaker or you risk it not tripping is that correct?
          Like you wouldn’t use a 50 amp breaker for a fridge even if you wanted to

          So does the same not apply for lights? It’s ok to oversize the breaker on those? Because no matter what I do my breaker is going to be way oversized for my lights

          The afci breakers are expensive it’s cheaper to just get the afci outlets

          1. Expert Member
            Akos | | #7

            "afci breakers are expensive it’s cheaper to just get the afci outlets"

            Be careful there. Our code requires armored cable (AC90) wiring form the panel to the AFCI outlet, from there you can go with regular romex. If you look at the cost of that, it is cheaper to use an AFCI breaker. Your electrical supply house should have panel kits that come with all the breakers and a bunch of AFCIs, much cheaper than buying them individually.

            If you want to save cost, best way is by not putting devices that don't need to be AFCI on an AFCI circuit. There is nothing wrong with a single AFCI breaker feeding all the outlets in two or three bedrooms.

          2. Deleted | | #10

            Deleted

        2. derekr | | #8

          We don’t have that code here I can just run all romex

          I definitely don’t have a choice with my outlets anyway with the length and voltage drop, they work out to being 80-110 feet runs per room anyway, trying to keep voltage drop under 5%

          1. Expert Member
            Akos | | #9

            I would double check that, our codes are not that different. There in an exemption for protecting the first run when doing retrofits but not for new construction.

        3. derekr | | #11

          My uncle just built a house a few months ago it was all romex

  3. russell1313 | | #12

    NM - Romex- is the best option for residential - unless some local codes require different. 15-amp 14 gauge is normally a lighting circuit, 12 for plugs/power. How many lights you put on a circuit depends on load. Use all LED and that is not an issue. Breakers must be AFCI/GFCI for almost everything, yes you can go the route at outlets but for new construction, it is not the way to go. Get a code book and go from there. Voltage drop is not an issue - in most cases. I just completed my home - everything is "spendy" now a days.

    1. derekr | | #13

      Even if I use afci outlets and regular breakers I can always change the breakers to afci later right?

      My question about the lights were if it was ok for the breaker to be oversized for them

      1. Expert Member
        Akos | | #14

        "lights were if it was ok for the breaker to be oversized"

        No problem at all. The smallest breaker you can install in a house is 15A so all devices are designed to work with that. Even if it is a single 10W LED, it will be fine on a 15A circuit and it would still need a 14-2 power feed even though it only consumes 0.09A.

        Your other question about the fridge is a big no. Most devices also have a maximum overcurrent protection device (breaker size) which you can't exceed. In case of the fridge it is probably 20A. Any larger device will have similar rating, they will have an MCA (min circuit size) and MOCP (max breaker size), you have to stay within those limits.

  4. jberks | | #15

    Hi Derekr,

    Let me try here regarding your concern with the breaker size.

    "But with appliances I guess you’re not supposed to oversize your breaker or you risk it not tripping is that correct?
    Like you wouldn’t use a 50 amp breaker for a fridge even if you wanted to"

    I think you're confusing load size and type here. Something like a motor running on a circuit, if it starts to malfunction slightly or get really inefficient and draws more than its rating, it will start using more amps and makes the wires feeding it hotter, possibly starting a fire. This is why you don't want to oversize the breaker to it, keeping the breaker at the manufacturers recommended amp rating is the safeguard.

    However, a lighting circuit is a lot simpler. If a 10W light malfunctions, its not going to draw more amps, and cause overheating issues on the wiring. Moreover, the 14gu wire ( in consideration with its total length) is rated for 15a of draw. So even if your lighting circuit somehow malfuctioned to start drawing 15a, it wouldn't cause the wires to overheat and start a fire. So its safe.

    But more in reality, if there was a short in the circuit somewhere in the line, that would draw lots of amps and thats what the breaker is there for. to stop the wires from overheating to catch on fire.

    So to answer your question: a 15a breaker with 14gu wiring with lights and wire length that aren't going over its load capacity is not the same thing as "oversizing" your breaker to an appliance.

    Disclaimer: I am not an electrician. and it sounds like neither are you. Don't trust random people on the internet with electricals.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |