General Lighting Circuits

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DBoone

DBoone

Senior Member
Location
Mississippi
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General Contractor
When you guys have receptacles and lights on the same circuit do you have any rules of thumb as far as how many amps of lights you will put on that circuit. Ex: 20 amp circuit - Load the circuit with a maximum of 10 amps of lighting and then finish the circuit with X number of convenience receptacles.
 
Between residential, apartments, commercial, industrial, institutional, education, etc. I avoid mixing lights and receptacles on the same circuit. Don't like to have a trip caused by a receptacle turning the lights off. Other reasons, but that one tops the list. IMHO.

RC
 
DBoone said:
When you guys have receptacles and lights on the same circuit do you have any rules of thumb as far as how many amps of lights you will put on that circuit. Ex: 20 amp circuit - Load the circuit with a maximum of 10 amps of lighting and then finish the circuit with X number of convenience receptacles.
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Are you talking commercial or residential ? I suspect the latter
 
DBoone said:
When you guys have receptacles and lights on the same circuit do you have any rules of thumb as far as how many amps of lights you will put on that circuit. Ex: 20 amp circuit - Load the circuit with a maximum of 10 amps of lighting and then finish the circuit with X number of convenience receptacles.
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Personally, I don't mix lights and receptacles in residential or commercial unless there's a compelling reason to do so. When laying out circuits for a residence, I tend to use 180VA/receptacle as a rule of thumb (not a requirement for residential), or higher if it's for a specific piece of equipment (e.g. 1200W home theater sound system gets its own circuit).

But I'm probably not the best source on this; I've never done anything like apartments or tract homes. The last residential project I worked on, you could fit two of my house into the guest house and still have room to spare. Main house was about 15,000 sq. ft., and then there was the pool house, etc., etc. So, yeah... a little out of my price range. But it was fun to work on, a nice change of pace.
 
In a residence it isn't much of an issue unless you have a tremendous load on the lighting. In most cases receptacles are not used often but they can be used for vacuums and such. Again it would depend on the number of receptacles for me. I have used one circuit to control a few bedrooms their lights as well as a bathroom. I think common sense can be used here. In a garage where a person may have a freezer refrigerator etc you may not want those receptacles on with a main room lighting circuit that has many cans or tracks etc.

Of course with LED becoming more common this issue is not much of a problem.
 
DBoone said:
When you guys have receptacles and lights on the same circuit do you have any rules of thumb as far as how many amps of lights you will put on that circuit. Ex: 20 amp circuit - Load the circuit with a maximum of 10 amps of lighting and then finish the circuit with X number of convenience receptacles.
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I really hate when other electricians mix receptacles with lighting. With everyone buying large surround systems, the new Dyson vacuums that have rating of 12 amps and people plugging in 1000 watt or higher rated heaters because they are told by some guy at Ace Hardware, Lowes,Menards or where ever, that they will heat up your whole house and save you energy. Pisses me off. Sorry I went off there. I see it with guys at the company I work for and it just ticks me off when I go to service call and I have to tell the homeowner sorry your 15 amp circuit is overloaded when your 10 can lights are on and when you run your vacuum.
 
Dennis Alwon said:
In a residence it isn't much of an issue unless you have a tremendous load on the lighting. In most cases receptacles are not used often but they can be used for vacuums and such. Again it would depend on the number of receptacles for me. I have used one circuit to control a few bedrooms their lights as well as a bathroom. I think common sense can be used here. In a garage where a person may have a freezer refrigerator etc you may not want those receptacles on with a main room lighting circuit that has many cans or tracks etc.

Of course with LED becoming more common this issue is not much of a problem.
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One advantage of the lights on same circuit as the freezer is you may notice no power at the lights sooner than you notice no power at the freezer if that should happen.
 
DBoone said:
When you guys have receptacles and lights on the same circuit do you have any rules of thumb as far as how many amps of lights you will put on that circuit. Ex: 20 amp circuit - Load the circuit with a maximum of 10 amps of lighting and then finish the circuit with X number of convenience receptacles.
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I think you need to consider what you're building. If you're building starter homes (<1500sf) the building is likely to have 15A circuits with 14/2 romex and combination lighting & receptacle circuits. If you're building 3,000 sf luxury homes, you're likely to have more deciated receptacles for home theaters, etc.

The answer is only as good as the question. What are you building?
 
mgookin said:
I think you need to consider what you're building. If you're building starter homes (<1500sf) the building is likely to have 15A circuits with 14/2 romex and combination lighting & receptacle circuits. If you're building 3,000 sf luxury homes, you're likely to have more deciated receptacles for home theaters, etc.

The answer is only as good as the question. What are you building?
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We usually build custom homes (3000sf and under). Your point is well taken...each job is different therefore what is on a circuit will vary depending on various factors.
 
We do mostly custom residential, and with the advent of the cursed AFCI's, we do one 15 amp circuit per bedroom, lights and receptacles. If there is a lot of incandescent lighting, such as a master bedroom w/ bathroom, we'll do one for lights and one for receptacles (plus the 20amp for the bath rec's). We've found it makes it easier for troubleshooting purposes.

And I know I will hear the wrath of the forum for using 15amp circuits, but I have yet to have any problem whatsoever with it. A 15amp circuit will cover a 1500 watt space heater and lights w/ no problem.
 
And I know I will hear the wrath of the forum for using 15amp circuits, but I have yet to have any problem whatsoever with it. A 15amp circuit will cover a 1500 watt space heater and lights w/ no problem.[/QUOTE]

1.5kw is 12.5amps on a 120v circuit. That's already over loaded your 80percent, then you put 6-65watt can lights on with that, now your past 15 amps. Sure the circuit will not trip right away, but it will sooner or later. So why would you put receptacles on with lighting, ever.

A 15 amp circuit will not cover a 1.5kw heater and lighting.
 
Ohms law said:
And I know I will hear the wrath of the forum for using 15amp circuits, but I have yet to have any problem whatsoever with it. A 15amp circuit will cover a 1500 watt space heater and lights w/ no problem.
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1.5kw is 12.5amps on a 120v circuit. That's already over loaded your 80percent, then you put 6-65watt can lights on with that, now your past 15 amps. Sure the circuit will not trip right away, but it will sooner or later. So why would you put receptacles on with lighting, ever.

A 15 amp circuit will not cover a 1.5kw heater and lighting.[/QUOTE]

electricguy61 said:
Nope, you meant 1.5kw.

I'm not loading the circuit, the customer is. Actual capacity is 1800 watts

Follows the code, never been a problem. And most bedrroms don't have 6 can lights.
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You only need to load the circuit to 80% when dealing with continuous loads. If that heater runs for 3 hours or more without cycling off, they either have a very large room, need to shut the doors or windows, or have some other really bad air leakage problem.
 
electricguy61 said:
Actual capacity is 1800 watts

Follows the code, never been a problem. And most bedrroms don't have 6 can lights.
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kwired said:
You only need to load the circuit to 80% when dealing with continuous loads. If that heater runs for 3 hours or more without cycling off, they either have a very large room, need to shut the doors or windows, or have some other really bad air leakage problem.
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I think you are forgetting 424.3(B). You can't put a 1.5kW heater on a 15A, 120V circuit, per 210.20(A).
 
david luchini said:
Sorry, thought it was referring to a fixed heater. A portable 1.5kW heater on a 15A, 120V branch circuit would be a violation of 210.23(A)(1).
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Do we as installers commit the violation when we do not know what the user will plug in sometime down the road? IMO that is one reason why we provide overcurrent protection so that users will not plug five heaters into such a circuit without something interrupting the overload condition. If one heater will hold the overcurrent protection, it is not overloaded.
 
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