# number of can lights for a 20 amp breaker

Discussion in 'Electrical and Wiring' started by adagaue37, Mar 12, 2008.

1. Mar 12, 2008

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I was wanting to put some recessed can lights in my entry and hallway for better lighting. I am considering the 4' Halo cans for remodeling. I was curious as to what the the recommended number of lights on a single circuit would be. I do not have a problem to put either a 15 or 20 amp breaker in and then running the new wire to the new lights. any help would be greatly apreciated.

2. Mar 12, 2008

### speedy petey

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Use the actual rating of the cans, probably 75 watts for the 4", to figure wattage.
Use the 80% figure for the circuit load for lighting such as this.

20A@120v = 2400 watts x 80% = 1920 watts ÷ 75 watts = 25 fixtures
15A@120v = 1800 watts x 80% = 1440 watts ÷ 75 watts = 19 fixtures

3. Mar 12, 2008

### OtbHunter

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Wow, thanks for that explaination speedy petey. I didn't know that was how to figure how many lights on a breaker. Very good information to know!

4. Mar 13, 2008

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Thanks Speedy Petey i really do appreciate the information. along the same lines if I use an existing run and it is not just lights but a mixture of lights and outlets what would the rule of thumb be on that. and if I use the fluorescent bulbs instead of the spot bulbs would you see a draw back to that? I am wanting to use the fluorescent replacements where I can to cut down on electrical usage and cost. currently 90% of the bulbs in my house are fluorescent bulbs.

5. Mar 13, 2008

### speedy petey

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In a home there is no limit to the number of receptacles on a circuit. We just use common sense when figuring circuits.
I try to keep it to no more than 8-12 receptacles. If there is lighting I just compensate for it.
Using the CFLs is a good idea, just still use the actual wattage rating of the fixture when figuring circuits.

6. Nov 20, 2008

### trips

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Basically your total amperage will equal your watts divinded by the volts.

AMPS = WATTS/ VOLTS

Example:

So if you were using a 20 amp breaker, 50 watt light bulb and 120 volt line, you would use the following. Remember, you want to use only 80% of the breaker capacity just to be safe and save worries later down the line.

Amps per light = 50 watt bulb / 120 volt

Each light would use .416 Amps.

80% of the 20 amp breaker would be 16 amps. Divide the 16 amp breaker by
.416 amps per light.

20 amps / .4545 amps per light = 38 lights.

Theoretically, you could use 38 lights.

7. Nov 21, 2008

### fluxcapacitor

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you are not allowed to use a 20A breaker for a lighting circuit in a dwelling unit (residential occupancy). It is against code (CEC). You must use a 15A breaker. It is common practise to not install more than twelve lights on a 15A breaker, regardless of the wattage of bulbs you use.

8. Nov 21, 2008

### speedy petey

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Keep in mind that "CEC" stands for the Canadian electric code. We do NOT have either of these restrictions here in the US.
Considering the OP is in the US I think this is important to mention.

9. Nov 22, 2008

### triple D

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Here in the states we can run a 15 or 20 amp lighting circuit. But not larger than that. And are only held to the max rating of all lights combined for circuit sizing, not number of them. Good luck on all your projects fellas....

10. Oct 15, 2010

### fasteddie

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Aren't normal canned lights wired with #14 wire? Can these be used in a 20 amp circuit?

11. Oct 15, 2010

### speedy petey

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In the US, recessed lighting can be wired with #14 on a 15A circuit or #12 on a 20A circuit. It does not matter.

12. Oct 18, 2010

### fasteddie

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I think I asked the question wrong. I plan to wire a room with #12 wire everywhere and feed the canned lights with #12 wire so that the entire room is on a 20 amp breaker. But it occurred to me that internally the light is most likely #14 wire. In other words when I splice in the canned light to the #12 wire, I am actually attaching a #12 to a #14. Is this a problem? If it is, then why are bathrooms usually 20 amp circuits including the lights, and bathroom fan?

13. Oct 18, 2010

### speedy petey

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The wiring inside the can is likely #18. It does not need to be more.
You are not connecting #18 to a 20A circuit. You are connecting a fixture to a 20A circuit.
The fixture wiring is NOT part of the branch circuit. It only needs to carry the load of the fixture.

14. Oct 22, 2010

### midway409

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I am kinda wondering the same thing? I have a family room in the basement that was in bad shape electrically. The former owner(s) used extension cords to wire outlets and duct tape splices everywhere. The 6 can lights 75W are wired using 14/2 G. So if I place the room on a 20 amp breaker with 6 outlets and 6 can lights, is that acceptable? Does the #14 need to be switched to #12?

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