Number of duplex recepticals?

[jwelectric]

Let?s look a little closer to article 220 than some are.

The title is: ARTICLE 220 Branch-Circuit, Feeder, and Service Calculations

This article is broken into five parts as follows:
I. General
II. Branch Circuit Load Calculations
III. Feeder and Service Load Calculations
IV. Optional Feeder and Service Load Calculations
V. Farm Load Calculation

The section of this article in question is Part II which is clearly for Branch Circuit Load Calculations.

Some think that the whole Article addresses services and feeders but this is not true as evidenced by the title of Part II and the first section of Part III.

III. Feeder and Service Load Calculations
220.40 General.
The calculated load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted by Parts III or IV or required by Part V have been applied.

Right or wrong I teach that the limits outlined in Table 220.12 General Lighting Loads by Occupancy can not be exceeded. Using this method a 15 amp circuit could not cover more than 600 square feet of floor space. (15X120/3)

 

[Joe R]

In commercial you are limited to the amount of receptacles to a circuit, but in residential, in a nutshell you are unlimited...

I agree with Stickboy, I read this in some electrical magazine, as to which one I don't recall, also think about a residential circuit and what kind of load is put on it, most receptacles in a home see little if no use, but in a commercial application the circuit would see a load almost at or close to capacity on any given day,sometimes a commercial circuit will get overloaded due to ,printers computers, fax machines etc which is the reason commercial electrical systems are always likely to see upgrading or changes. But in desgining a residential electrical circuit the electrician would consider the type of home and what kind of load the circuits would be put under that would tend to limit the receptacles on a residential circuit.

 

[iwire]

Right or wrong I teach that the limits outlined in Table 220.12 ....

Can we keep this thread directly on only the number of receptacles on a circuit?

If you want to talk about 220.12 I respectfully ask you start a new thread to do so.

 

[jwelectric]

Sorry Bob didn?t mean for it to seem like I was high jacking the thread so let me explain my thoughts a little clearer.

In Part II of 220 it addresses branch circuits and their loads. Table 220.12 addresses the lighting load for all occupancies and 220.14 addresses Other Loads ? All Occupancies.

In 220.14 (H)&(I) we see the load for fixed multioutlet assemblies and receptacles that would be applied in a commercial/industrial application.

Looking at 220.14(J) we are told that the receptacles in a residential occupancy are to be included in the general lighting load of three watts per square foot. There is no restriction as to the number of receptacles that can be installed.

As to whether 220 addresses the load for a service or feeders we have to look at Part III of that article for the load on these conductors, see 220.44 for the requirements for receptacles. Part I is for the load on branch circuits.

My reference to the 600 square feet was just to say that the only restriction on the residential receptacles is the watts per square feet rule of 220.12 and no set number is mentioned nor a load set for each device as in 220.14(H)&(I).

 

[LarryFine]

The title is: ARTICLE 220 Branch-Circuit, Feeder, and Service Calculations.

Bold added by me.

 

[iwire]

Larry we all agree it says calculations.:grin:

So we use 220 to make the calculations and then we can ignore those calculations? Seems odd to me....is it just a math exercise?

 

[George Stolz]

I was curious as to what the results of a poll would be, and since this topic is pretty lively (and seemingly divided) on the subject, I asked the original poster if I could start a poll in his thread; he graciously agreed.

So, a quick show of hands: what do you think? Is the information in Article 220 applicable when branch circuits are laid out in a commercial setting, or can we exceed 13 for a 20A circuit as long as the service is right?

 

[Jomaul]

I have a question , in 210.11 it says branch ckrts shall be provided to supply the loads calculated in accordance with 220.10, 220.10 says loads shall be calculated as shown in 220.12,.14, & .16.. Article 220.14(I) says receptacle outlets will be calculated at 180va for each single or multiple receptacle on 1 yoke except in dwellings and banks, and in 220.14 (L) says outlets not covered in 220.14a - k shall be calculated at 180 va, so wouldn't this limit the number of outlets on a ckrt in some commercial projects?

 

[jwelectric]

We've been through this before, Bob. Click on the link Dennis posted, to see the old discussions. But as a general summary statement of my view, can you show me where the NEC commands me to design circuits using 180 VA per receptacle? Please be sure that you do not cite article 220 in your answer. Branch circuits are described in 210, not 220.

Point in fact, I do choose to use 180 VA per receptacle as a design criterion. But I don't have to.

Charlie,
To cite the requirement for the installation of receptacles on a branch circuit and not quoting article 220 would be like proving that a light bulb works without energizing it. I can prove that bulb should work but I can?t prove that it does in fact work without energizing it.

Look at section 210.11 (2005 cycle)

210.11 Branch Circuits Required.

Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads calculated in accordance with 220.10. In addition, branch circuits shall be provided for specific loads not covered by 220.10 where required elsewhere in this Code and for dwelling unit loads as specified in 210.11(C).

In the first sentence of this section states; Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads calculated in accordance with 220.10

In order to know just what is being supplied by these required branch circuits in 210.11 one must look at section 220.10 which states; 220.10 General. Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.16.

220.14(I) clearly states that a yoke with three or less receptacles is to be calculated at no less than 180va each except as outlined in 220.14(J) and (K). On a 20 amp circuit 120x20/180 leaves us with the maximum number of receptacles allowed on the circuit required by 210.11.

It is not a design choice but a requirement found in 210.11 that determines the number of receptacles on a branch circuit.

EDITED TO ADD

Yea what Jomaul said. He posted while I was working on my post.

 

[electrojet]

Number of recepts per ckt

Number of recepts per ckt

NEC has different conditions pertaining to the # of recepts on a ckt. As far as single family dwellings, two familiy dwellings multifanmily dwellings and in guest rooms or guest suites of hotels and motels, section 220.14 J 1,2,3 specifies that these recepts are "included int he general lighting load calculations of 220.12 " .....table 220.12 dwelling uniits, specifies 3 v/a per square foot of unit space and note (a) refers to 220.14 (J). This indicates that the requirement of 180v/a per recptacle does not apply to most receptacle outlets in dwelling units.

 

[splinetto]

Isn't ALL of 220 there to figure out the service size needed per the sq ft , lighting, motors and etc. It would seem to me that the 3va/ft is just for servive calc... I agree there should be a limit but I don't see it in the book. The other thing is that volt amps are apparent power , just because you have the posibility of 180va at an outlet doesn't mean 1.5 amps are being used..

 

[stickboy1375]

Isn't ALL of 220 there to figure out the service size needed per the sq ft , lighting, motors and etc. It would seem to me that the 3va/ft is just for servive calc... I agree there should be a limit but I don't see it in the book. The other thing is that volt amps are apparent power , just because you have the posibility of 180va at an outlet doesn't mean 1.5 amps are being used..

If Article 220 were ONLY for service calculations, wouldn't it be called Article 220 Service Calculations?

 

[splinetto]

My Question would be. What if you would go over the 3va lighting load in Table 220.3(a) For the entire building. I say it would not matter because the 3va is for calc the serv needed. You would just need more ckts not a bigger service.. So I'm assuming that the 3va for lighting and the 180va for outlets are for calculations.. Hope I m explaining what im trying to say

 

[dab]

does the analogy" i can't be broke, i still have checks" ring a warning bell?

 

[jwelectric]

My Question would be.

Then explain this section to me please

210.11 Branch Circuits Required.
Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads calculated in accordance with 220.10. In addition, branch circuits shall be provided for specific loads not covered by 220.10 where required elsewhere in this Code and for dwelling unit loads as specified in 210.11(C).

 

[tryinghard]

...can you show me where the NEC commands me to design circuits using 180 VA per receptacle? Please be sure that you do not cite article 220 in your answer. Branch circuits are described in 210, not 220

Charlie, we do not have to cite article 220 because article 210 does this for us in 210-11 which tells us branch circuits for lighting and appliances? SHALL be provided to supply the loads computed in accordance with 220-10

How would 210-20(A) apply for non-dwelling receptacles in your opinion?

 

[tryinghard]

I am in the 'Not Limited' camp.

Curious, how many non-residential construction drawings have you seen with more than 13 receptacles on a 20A circuit?

 

[LawnGuyLandSparky]

Curious, how many non-residential construction drawings have you seen with more than 13 receptacles on a 20A circuit?

I've seen dozens where 20 floors of janitor or electrical closets were fed by 2 circuits - one for the lighting and one for the maintainence outlet.

 

[ryan_618]

I am definately in the camp of "180VA".
Can someone from the other camp explain why Part II of Article 220 even exists if it isn't to be used?

 

[charlie b]

I am definately in the camp of "180VA".

Can someone from the other camp explain why Part II of Article 220 even exists if it isn't to be used?

It is to be used to calculate load, so as to make sure that the service has enough capacity, and that the feeder to any panel has enough capacity. It is not to be used to design branch circuits, as the NEC does not tell us how to design anything.