Max recep #on 120 v circuit?

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How do you determine the max number of 20 amp receps on a 120 volt CRkt? It's a commercial bld. 220.14 (I) states 180 va each. Do you use 210.21(b)(2) 16 amps giving you 10 receps? I know it seems elementary but trying to site it. Thanks in advance
 

Smart $

Esteemed Member
Location
Ohio
Been debated with no absolute resolution... but the majority go with 120V times 20A divided by 180VA, yielding a maximum of 13 per circuit. You go with the full 20A noncontinuous in the determination because until you plug something in, there is no actual load on the circuit. And if you know a continuous load will be plugged in, then that load would be a specific load and not a general-purpose receptacle load.
 

Gregg Harris

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Location
Virginia
How do you determine the max number of 20 amp receps on a 120 volt CRkt? It's a commercial bld. 220.14 (I) states 180 va each. Do you use 210.21(b)(2) 16 amps giving you 10 receps? I know it seems elementary but trying to site it. Thanks in advance

If it is not a bank or office building 220.14(K), you would use (L) = 13
 

charlie b

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Just to be clear, and not to reopen any debates, one of the points of view is that there is no limit. This interpretation is based on the fact that the calculation of loads is discussed in 220 and the requirements for branch circuits are discussed in 210, and takes note that nothing in either section requires you to refer to the other.
 

Smart $

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Just to be clear, and not to reopen any debates, one of the points of view is that there is no limit. This interpretation is based on the fact that the calculation of loads is discussed in 220 and the requirements for branch circuits are discussed in 210, and takes note that nothing in either section requires you to refer to the other.
The point of contention to that view is 210.11, which specifically refers to 220.10, which in turn specifically refers to 220.14. The debate then centers around 220.14(J) because most receptacles in dwelling units are included in the general lighting load calculation and no specific load value for receptacles. The counter argument gains support when involving other than dwelling units, where specific load values are assigned based on VA per receptacle or yoke.
 

charlie b

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The point of contention to that view is 210.11, which specifically refers to 220.10. . . .
210.11 only tells you to provide branch circuits to supply the calculated loads. It does not tell you how to design the branch circuits. On the other hand, 220 is all about making sure there is enough load accounted for in the overall design to provide the minimum requirements. It too does not tell us how to design branch circuits.

Suppose the calculated load associated with receptacle loading winds up being equivalent to 180 VA per receptacle times 40 receptacles. I could lay out a design that has five branch circuits supplying that load, with 20 receptacles on one circuit and 5 receptacles on each of the other four. I don't like that design, and I wouldn't do it. All I am saying is that the words of the NEC, as written, do not include any cross-references between 210 and 220 that would forbid it.

 

Smart $

Esteemed Member
Location
Ohio
210.11 only tells you to provide branch circuits to supply the calculated loads. It does not tell you how to design the branch circuits. On the other hand, 220 is all about making sure there is enough load accounted for in the overall design to provide the minimum requirements. It too does not tell us how to design branch circuits.

Suppose the calculated load associated with receptacle loading winds up being equivalent to 180 VA per receptacle times 40 receptacles. I could lay out a design that has five branch circuits supplying that load, with 20 receptacles on one circuit and 5 receptacles on each of the other four. I don't like that design, and I wouldn't do it. All I am saying is that the words of the NEC, as written, do not include any cross-references between 210 and 220 that would forbid it.

And I agree!!!

I just wanted elaborate on the points of contention in the debate.
 

greenspark1

Senior Member
Location
New England
I continue to be amazed how even seemingly straightforward sections of the Code really aren't that clear. Try explaining this murkiness to a client/architect! Nothing is as simple as it seems.
 

Dennis Alwon

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Chapel Hill, NC
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Let me digress. If article 210 was just for calculation then ranges could not be wired as they are currently using T220.55. I have not seen anyone teach a class where the range had to be wired based on the nameplate of a range. All classes teach to use the table for the branch circuit.

The title of 220 is Branch circuit, feeder and service calculations. Now what is the sense of calculating a branch circuit if we cannot wire it using the calculation. Art 220.14(I) is receptacle loads-- does it say only for feeder or service calculations? No so IMO it would also be used for branch circuit calculation and that means 13 receptacles on a 20 amp circuit for non residential work.
 

Dennis Alwon

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I can also tell you that if you wire the receptacles paying no mind to 180va then you will probably not pass. If there are plans then I guarantee they will not have more than 13 receptacles per circuit
 

Smart $

Esteemed Member
Location
Ohio
Let me digress. If article 210 was just for calculation then ranges could not be wired as they are currently using T220.55. I have not seen anyone teach a class where the range had to be wired based on the nameplate of a range. All classes teach to use the table for the branch circuit.

The title of 220 is Branch circuit, feeder and service calculations. Now what is the sense of calculating a branch circuit if we cannot wire it using the calculation. Art 220.14(I) is receptacle loads-- does it say only for feeder or service calculations? No so IMO it would also be used for branch circuit calculation and that means 13 receptacles on a 20 amp circuit for non residential work.

I can also tell you that if you wire the receptacles paying no mind to 180va then you will probably not pass. If there are plans then I guarantee they will not have more than 13 receptacles per circuit
I believe Charlie B and I are trying to avoid further debate, as we both know there will be no definite resolution. :happyno:

Suffice it to say, professionals throughout the industry tend to make generalizations in implementing the Code rather than applying nuances as they arise... that is, if they even realize what the nuances entail. Many do not, because they simply follow what is generally practiced and accepted throughout the trade...
 

charlie b

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I believe Charlie B and I are trying to avoid further debate, as we both know there will be no definite resolution. :happyno:
I agree.
Now what is the sense of calculating a branch circuit if we cannot wire it using the calculation.
What is the sense? There is none. But that is not relevant. My only point is that the words, as written, don't establish a limit. The words you want to use, to back up your sense of how the circuits should be installed, are simply not there. I seldom lay out a design with more than 6 or maybe 7 receptacles on a single circuit. But that is because I believe this is the right thing to do, not because I believe the code requires it.



 

Dennis Alwon

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And yet here we are :D

What is the sense? There is none. But that is not relevant. My only point is that the words, as written, don't establish a limit.

Here is where I disagree to an extent- the code does not say that this is only for calculation and not to be used for branch circuits either. I just don't see how we can ignore the title mentioning branch circuits and then decide the 180va has nothing to do with branch circuits. So be it. I will stop now--- maybe...:p
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
I can also tell you that if you wire the receptacles paying no mind to 180va then you will probably not pass. If there are plans then I guarantee they will not have more than 13 receptacles per circuit

I agree. And if was a licensing exam question, I would suggest answering 13. That's the way I've always seen it taught in code courses.
 

Smart $

Esteemed Member
Location
Ohio
And yet here we are :D



Here is where I disagree to an extent- the code does not say that this is only for calculation and not to be used for branch circuits either. I just don't see how we can ignore the title mentioning branch circuits and then decide the 180va has nothing to do with branch circuits. So be it. I will stop now--- maybe...:p
IMO your disagreement is not without merit, so let's address your concern regarding a range branch circuit...

There are instances where Article 220 calculations are used in sizing branch circuits under Article 210. First we have 210.11 general statement. Note it specifically refers to lighting and appliance loads as calculated in accordance with 220.10, which direct us specifically to 220.12, 220.14, and 220.16. Note general-use receptacles are under 220.14 but not mentioned in the general statement of 210.11.

With regard to your example of a range, that would be a specific appliance under 220.14(A)... so the general statement of 210.11 applies and subject to the load calculation of 220.10. Furthermore, 210.21(B)(4) specifically says "The ampere rating of a range receptacle shall be permitted to be based on a single range demand load as specified in Table 220.55." The receptacle rating then limits the circuit rating and thus its OCPD rating.

Any questions? :D
 
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