How many items on a breaker

Status
Not open for further replies.

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Master Electrician
How many outlets and lights do you put on a circuit? Were talking normal residential, with all LED lighting. In the past I would put 10-12 items. What do you all do?
 

templdl

Senior Member
Location
Wisconsin
How many outlets and lights do you put on a circuit? Were talking normal residential, with all LED lighting. In the past I would put 10-12 items. What do you all do?

You are getting the cart before the horse. Breasker's protect wire. Have you give any thought in regard to sizing the wire to carry the load? Have you referred to the NEC art 220 followed by art 240? These are the basics of sizing wire and selecting an OCPD to protect the wire.
 

JFletcher

Senior Member
Location
Williamsburg, VA
If you size all of your lighting circuits based on LED, you could just about put the entire house's lights on one 20A breaker, load wise. Stick to your usual, there is no telling what a future HO might put in those light fixtures.
 

templdl

Senior Member
Location
Wisconsin
120v 20 amp =2400w
120v 15 amp=1800w
Ixe =p
Nec art 220 and 240


Sent from my iPhone using Tapatalk

Continuous or non continuous? Breakers protect wire and wire is sized based upon NEC art 220. Let's not get the cart before the horse as technically breakers end up to be applied a 80% of their rating. Yes. 120v X 20a is 2400w but that is based upon 100%. If a breasker in coomonly applied at 80% of its rating then that 2400w ends up to be actualy 1920w continuous. That is why it is important for the wire to be sized first based upon the computed load per NEC art 220. The the breaker rating selected to protect the wire then is based upon NEC art 240.
 

templdl

Senior Member
Location
Wisconsin
12 amps on 15 amp circuit and 16 amps on 20 amp circuit

Yes, exactly. This is where the 80% comes into play. So when your figure is more than 12a continuous for a #14 wire rated at 15a protected with a 15at breaker but less than 16a continuous you then step up to a #12 wire that is rated 20a protecting it with a 20at breaker. It is relatively a very basic application which can be made much more comp!icated than necessary.
 

templdl

Senior Member
Location
Wisconsin
Templdl
Your correct
80 percent
is 1920 watts

Sent from my iPhone using Tapatalk

Personally I don't like getting the cart before the horse by the 1920w figure as it may be misleading as beakers protect wire and the wire size should be based upon that 1920w continuousand not the breaker which ends up to be 80% the rating of aa 20a rated #12 wire. Then protect the wire with a 20at breaker. The breasker's protects the wire and there is no need to know the load on the breaker. People make this so complicated.
 

480sparky

Senior Member
Location
Iowegia
My magic number is 12. Duplex receps count as 1, lights are ½. So, 12 receps and 0 lights, or 6 receps and 12 lights. Or 8 receps and 8 lights.

That's for a 15a circuit.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
My magic number is 12. Duplex receps count as 1, lights are ½. So, 12 receps and 0 lights, or 6 receps and 12 lights. Or 8 receps and 8 lights.

That's for a 15a circuit.

I like it. :cool:

At least that is how I wired before AFCIs, then after that it was 3va per foot :cry:
 

iwire

Moderator
Staff member
Location
Massachusetts
Personally I don't like getting the cart before the horse by the 1920w figure as it may be misleading as beakers protect wire and the wire size should be based upon that 1920w continuousand not the breaker which ends up to be 80% the rating of aa 20a rated #12 wire. Then protect the wire with a 20at breaker. The breasker's protects the wire and there is no need to know the load on the breaker. People make this so complicated.

On the one hand you are right. :)


On the other hand that is not how it is commonly done in the field when running 15 & 20 amp circuits branch circuits in a dwelling unit.

Dwelling units have lights and receptacles, those are going to be wired with 12 or 14 AWG. Those wire sizes are pretty much set in stone.

Along with that we know that we will use 20 amp breakers with the 12 AWG and 15 amp breakers with the 14 AWG. That is also pretty much set in stone.

So now we know the wire size and the breaker sizes we will be using. It is a done deal. No calculations needed.


Many electricians wire the entire home with 14 AWG except for the code required 20 amp circuits in the Kitchen, dinning rooms etc. So we already know what outlets will get the 12 AWG 20 amp circuits.


Now lets wire the house. We start with a roll of 14 AWG at the panel that will be supplied by 15 amp breaker. I already know I have to avoid the 20 amp outlets but I want to use the wire in the most efficient way I can feeding receptacles and lighting outlets as I see fit ... up to a certain number of outlets .... plus or minus dependent on our moods. :p

So that is why the electricians here keep posting the number of outlets they supply and no one is really talking amps or va or article 220.

What is the correct amount of VA to assign to a general purpose duplex receptacle in a dwelling unit? There isn't one, that is why we use our experience to determine how many outlets on a 15 or 20 amp circuit.


Now for specific loads like an HVAC unit I agree 100%, start with the load, select a conductor and finally select an OCPD. :)
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
Why? What do AFCIs have to do with 3va/sq ft?

Nothing until you do the math. Adding an extra circuit was not an issue (back then), but when you factor in $45 per breaker and no MWBC running the minimum amount of circuits codes requires becomes attractive.
 

iwire

Moderator
Staff member
Location
Massachusetts
Hold up guys, let's start a new thread if you want to keep talking about how to distribute the circuits.

The OP started this thread about how many items on a breaker, let's try to stay on that in this thread.
 
Status
Not open for further replies.
Top