receptacles

[domnic]

How many receptacles can I put on a 20 amp breaker in a single family dwelling general lighting ?

 

[rcarroll]

How many receptacles can I put on a 20 amp breaker in a single family dwelling general lighting ?

Pretty much as many as you want in 800 sq. ft.
800sq. ft x 3 watts per sq. ft. = 2400 w divide by 120 v = 20 amps.

 

[Ponchik]

Pretty much as many as you want in 800 sq. ft.
800sq. ft x 3 watts per sq. ft. = 2400 w divide by 120 v = 20 amps.

where did the 800sqft come from? or was it just an example?

 

[rcarroll]

where did the 800sqft come from? or was it just an example?

General lighting circuits are calculated at 3 w per sq. ft. Correct?
15 a ckt would be 600 sq. ft.

 

[infinity]

How many receptacles can I put on a 20 amp breaker in a single family dwelling general lighting ?

Put on as many as you want.

 

[kwired]

Pretty much as many as you want in 800 sq. ft.
800sq. ft x 3 watts per sq. ft. = 2400 w divide by 120 v = 20 amps.

So how do you know when you have too much on any individual circuit if a particular 800 square foot area is served by multiple branch circuits? Complicate that by the fact those multiple circuits maybe supply outlets in areas outside the 800 we somehow have narrowed down.

How many square feet does an outdoor receptacle or even lighting outlet which is permitted to be on same circuit as many interior rooms cover?

IMO the 3VA per SF is intended to be a value to be used for feeder/service calculations, and to complicate things the SF includes areas that are to be supplied by SABC's which are already included separately in the feeder/service calculations at 1500 VA each as well as the 1500 VA laundry circuit. I do agree that if that is the intention it is not all that clear, but there is so many things that do conflict with the 3VA principle as well.

 

[rcarroll]

So how do you know when you have too much on any individual circuit if a particular 800 square foot area is served by multiple branch circuits? Complicate that by the fact those multiple circuits maybe supply outlets in areas outside the 800 we somehow have narrowed down.

How many square feet does an outdoor receptacle or even lighting outlet which is permitted to be on same circuit as many interior rooms cover?

IMO the 3VA per SF is intended to be a value to be used for feeder/service calculations, and to complicate things the SF includes areas that are to be supplied by SABC's which are already included separately in the feeder/service calculations at 1500 VA each as well as the 1500 VA laundry circuit. I do agree that if that is the intention it is not all that clear, but there is so many things that do conflict with the 3VA principle as well.

I suppose I came up with that as the OP's question was for a dwelling general lighting circuit. No SABC's, laundry, etc, were a part of the question.
In the past, the standard answer on this site for "how many receps on a 15 a ckt?" is "as many as you want in 600 sq. ft.
Maybe I assumed more than I should have.

 

[Ponchik]

General lighting circuits are calculated at 3 w per sq. ft. Correct?
15 a ckt would be 600 sq. ft.

This may be a good design or a good practice but I say you can put as many as you want. Some are used to 13 per 20A or 9 per 15A.

 

[Dennis Alwon]

I think one can argue what Ron is saying. If we calculate the loads at 3 va/ sq.ft then I could see an inspector saying that you cannot have more than 600 sq. ft for a 15 amp cir. That would be like 3 large rooms 13x15 sq. ft. The problem I have with this is as soon as you install another circuit in this area for lighting then how do you calculate the sq.ft.

3 rooms that total 600 sq.ft but there is a lighting circuit in there as well--that makes it hard to do that. The NEC does say how many receptacles but rather how many circuits. If you have a 2000 sq. ft house then you would need 3va/sq.ft. 6000/1800= 4 cir. at 15 amps

 

[kwired]

I think one can argue what Ron is saying. If we calculate the loads at 3 va/ sq.ft then I could see an inspector saying that you cannot have more than 600 sq. ft for a 15 amp cir. That would be like 3 large rooms 13x15 sq. ft. The problem I have with this is as soon as you install another circuit in this area for lighting then how do you calculate the sq.ft.

3 rooms that total 600 sq.ft but there is a lighting circuit in there as well--that makes it hard to do that. The NEC does say how many receptacles but rather how many circuits. If you have a 2000 sq. ft house then you would need 3va/sq.ft. 6000/1800= 4 cir. at 15 amps

Exactly, there are some circuits that can only serve certain areas like SABC, laundry, bathroom - now the garage, but most other circuits are unlimited to what can be on with what. One could easily have most of the lighting outlets on entire floor in some cases and never overload a 15 amp breaker, but these lighting outlets may be serving well over 600 sq feet of space. Chances are there are other circuits in that space serving receptacle outlets, but how can one say a 15 amp circuit can only serve 600 square feet?

I have never bought into the idea that we need to serve a specific number of outlets or a specific square footage with general lighting branch circuits. Often times there are many receptacles with nothing plugged in, or they have very limited load the majority of the time, we also have for non dwellings a figure of 180 VA per outlet which does make more sense IMO then assigning one circuit to x amount of square feet, though I still question the practicality of that concept in some instances. Bottom line from my experiences is not every owner/occupant loads a building to the same density per square foot, but dwellings do seem to be more consistent with having lightly loaded receptacle outlets on average in rooms outside the SABC required rooms, laundry, bath - and maybe the garage.