Amount of Receptacles on one circuit

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GreggSpicer

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Is there anything in the NEC that limits the amount of receptacle on one circuit in residential? Someone told me it was no more than 12 and someone else told me there is nothing specified in the NEC and that 12 was the rule a thumb. Does anyone know?
 
As an instructor, are you willing to teach your students that some issues are not clear, that there are arguments both in favor and against a given point of view, and that sometimes no answer is fully correct? I hope so, for this is going to be one of those issues.

I am not good at doing searches. Perhaps someone could search for the previous debates on this question? I would rather not go through it all in a fresh debate.

p.s. My answer, and many will disagree, is that there are no limits, and that answer does not change with the type of occupancy.
 
Charlie is correct (of course).
For your study, the rule most folks refer to and the one that causes some controversy is located at 220.14 (I) and (J). You will note, non-dwelling units are figured at 180 va per yoke, but dwellings are referred to 220.12 which is based on square footage. This results in the controversy that the number is unlimited in dwellings as the only limit is sq ft, BUT, this appears in Art 220 which is calculations and not actual wiring methods. Thus the controversy.
Did I do that right charlie ?

also note some local jurisdictions such as mine (State of TN) have restrictions.
 
Well,

If it's 180VA per receptacle, and you have 120V...then each receptacle is allotted 1.5A. Taking the 20A circuit breaker and dividing that number by 1.5A, you come out with 13 receptacles. Often in different locales the general rule of thumb is 12 allowed, 10 installed for a 20A circuit. But I'm sure everyone has their own method/rule of thumb, this is just what I've been taught.
 
Yes, Gus, you have my views correctly summarized. Essentially, 220 is all about making sure that the service and the feeders are correctly sized for the anticipated total load. But the NEC is not a design manual. Nothing in 210 tells you to design circuits in accordance with the 180 VA that appears in 220. That is the reason I say there are no limits.

As to the "12 allowed, 10 installed" thumb rule, some people will amend your calculation to say that you are limited to using 16 amps on a 20 amp circuit (i.e., 80% loading). Thus, you divide 16 by 1.5, get an answer of 10.67, and conclude that the limit is 10.
 
I understand the point , that this is just load calculation... And I really don't know that I disagree... but...the calculation is under Part II of the article: Branch Circuit Load Calculations.


I don't see the point of calculating the load of a branch circuit and then completely ignoring the calculations when actually constructing the circuit?
 
I don't advocate ignoring it. But what compels me to follow it?

This is about the wording, as it actually appears in the book. Best practices, good circuit design, and rules of thumb are entirely different matters.
 
icefalkon said:
Well,

If it's 180VA per receptacle, and you have 120V...then each receptacle is allotted 1.5A. Taking the 20A circuit breaker and dividing that number by 1.5A, you come out with 13 receptacles. Often in different locales the general rule of thumb is 12 allowed, 10 installed for a 20A circuit. But I'm sure everyone has their own method/rule of thumb, this is just what I've been taught.
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None of that applies to residential dwellings.

Roger
 
I know, that is for commercial installations. According to code handbooks for 2008, 2005, and 2002 the wording is almost the same:

"Although the Code gives the previously described data on maximum permitted number of receptacle outlets in commercial, residential, institutional and other nonresidential installations, there are no such limitations on the number of receptacle outlets on residential branch circuits. There are reasons for this approach.

In 210.52, the Code specifies where and when receptacle outlets are required on branch circuits. Note that there are no specific requirements for receptacle outlets in commercial, industrial, and institutional installations other than for store show windows in 210.62 and roof A/C equipment in 210.63. There is the general rule that receptacles do have to be installed where flexible cords are used. In nonresidential buildings, if flexible cords are not used, there is no requirement for receptacle outlets. They have to be installed only where they are needed and the number of spacing of receptacles are completely up to the designer. But because the Code takes the position that receptacles in nonresidential buildings have to be installed where needed for connection of specific flexible cords, it demands that where such receptacles are installed each must be taken as a load of 180VA.

A different approach is used for receptacles in dwelling type occupancies. The Code simply assumes that cord connected appliances will always be used in all residential buildings and requires general purpose receptacle outlets of the number and spacing indicated in 210.52 and 210.60. These rules cover one family houses, apartments in multifamily houses, guest rooms in hotels and motels, living quarters in dormitories, and so forth. But because so many receptacle outlets are required in such occupancies and because use of plug connected loads is intermittent and has great diversity of load values and operating cycles, the Code notes at the bottom of Table 220.3(A) that the loads connected to such receptacles are adequately served by the branch circuit capacity required by 210.11, and no additional load calculations are required for such outlets."

So, by that...there is no limit to the number of outlets on a circuit in a dwelling unit...correct?
 
augie47 said:
Charlie is correct (of course).
For your study, the rule most folks refer to and the one that causes some controversy is located at 220.14 (I) and (J). You will note, non-dwelling units are figured at 180 va per yoke, but dwellings are referred to 220.12 which is based on square footage. This results in the controversy that the number is unlimited in dwellings as the only limit is sq ft, BUT, this appears in Art 220 which is calculations and not actual wiring methods. Thus the controversy.
Did I do that right charlie ?

also note some local jurisdictions such as mine (State of TN) have restrictions.
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I'm not sure what you're saying in the bold part. Following the phrase "that the number is unlimited in dwellings as the only limit is sq. ft. " with a BUT seems to indicate that the number IS limited.

It sounds as though Charlie doesn't think there is a maximum number of recepts. on circuits in ANY occupancy.

Are you saying that the only purpose for Art. 220 is to calculate total service load? And that there is no limit to the number of general purpose recepts that can be put on a circuit in ANY occupancy?


Is it because there is nothing specifically saying that there is no maximum that it is permissible to put as many as you want on a circuit or what? That seems odd to me when 220 specifically tells you how to calculate them in a part specifically for branch circuits.

Not arguing... I want to know.
 
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I will refrain from my personal outlook and simply say that Art 220 provides means for calculating loads on branch circuits and Art 210 provides the rating of the circuits and other specifics. The relationship between the two Articles is where the controversy lies.
A number of people are satisfied with the scenario icefalkon posted, but not all are.
If, as Charlie suggest, you do an extensive search, the various outlooks have been debated previously.
 
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Regardless of any debate and/or opinions of the wording of 220.14, we need to be sure and point out that all study materials teach that there is no limit on residential dwelling units and 180 va is applicable for other than dwellings, the same as the following commentary from the NECH does.

In Exhibit 220.4, the maximum number of outlets permitted on 15- and 20-ampere branch circuits is 10 and 13 outlets, respectively. This restriction does not apply to outlets connected to general lighting or small-appliance branch circuits in dwelling units
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If we teach otherwise and a student misses a question we have done them a disservice IMO.


So with that said, anyone taking an exam in the near future should take the commentary quoted above as gospel. :)

Roger
 
roger said:
So with that said, anyone taking an exam in the near future should take the commentary quoted above as gospel. :)

Roger
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Handbook dogma?

I'm sure glad it is gospel because the gospel never gets debated. :grin:
 
You are unlimited but keep in mind that if they trip breakers they are calling you. In todays world of computers and tv i would give the master bedroom its own circuit and #2 and # 3 could share 1 circuit. I would design the install based on rooms and not number of receptacles. A bed room might be 20 x 20 and have them every foot but usage per room would not change much. Teach them about design and not numbers. Do make sure they know there is no limit as far as nec in residential. The idea behind 12 is a good practical number but not code.
 
realolman said:
It sounds as though Charlie doesn't think there is a maximum number of recepts. on circuits in ANY occupancy.
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That is indeed my opinion.
realolman said:
e you saying that the only purpose for Art. 220 is to calculate total service load? And that there is no limit to the number of general purpose recepts that can be put on a circuit in ANY occupancy?
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Yes, and yes, in that order.
realolman said:
Is it because there is nothing specifically saying that there is no maximum that it is permissible to put as many as you want on a circuit or what?
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No. It is because 210 does not contain a reference to 220. I can design branch circuits however I wish. In practice, I do use 180 VA per receptacle as a design consideration. I just have never found anything in the NEC that tells me that I must.
 
You see, this is where a LOT of problems happen. From discussions like this, journeymen in the field...some of whom haven't looked at a code book in years take information and run with it like yellow belts in karate.

I can see someone relatively new to the trade, or who hasn't looked at a code book since 1999 coming on this thread and going to work tomorrow stating to the crew...

"Hey, some guys on that code forum say that we can put as many outlets on a circuit as we want!"

Then he'll go wire his sisters house, or do a side job, and next thing you know there are more and more houses wired like they were in the 60's! Worse yet, so will the 10 guys on his crew!

I ran new residential construction for 5yrs straight and can say this, we never ran more than 12 receptacles on a 20A breaker. Now I understand what the discrepancy is, and I understand that the Code is being interpreted as there is no limit in a dwelling unit...however, common sense has to come into play somewhere.

How many times have you gone to an in-law's house because of a small problem and did the "sigh" when you find out that all the outlets in the house are on two 20A breakers...other than the two for the kitchen? How many times have those who do service calls go to a home because of a tripping breaker and find the whole house is dark?

IMO this is a "dark area" that should be addressed. Let the Code Committee come up with a number set in stone and be done with it. Other items in the Book can be dealt with down to the smallest minutia, but something like this, that affects everyone should have a direct number associated with it. I know I'll probably get a lot of flack for this, but it's just my opinion.
 
icefalkon,

The trouble is a code rule has to cover more than just a common installation. For example:

Say I wanted plugmold with 4" on center recpts on all my bedroom walls, 4 circuits per

bedroom is not a sane install either, this is what the CMP's have to think about.
 
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