GFCI Receptacles

[sarsenault]

The code seems very clear on installing GFCI receptacles in Residential applications, but for a commercial installation, what is the maximum number of 120V/20A GFCI receptacels that can be put on a 20A circuit? Where is this stated in the NEC? Thx.

 

[raider1]

what is the maximum number of 120V/20A GFCI receptacels that can be put on a 20A circuit? Where is this stated in the NEC?

13, Take a look at 220.14(I). This requires that receptacle outlets in a non-residential structure be calcultated at not less than 180 volt-amperes.

Chris

 

[charlie b]

It's not stated anywhere.


There are some that believe there is an NEC limit on the number on receptacles that can be installed on 20 amp circuits. I am not among them. (Edited to add that I see Chris is among them, since his post hit the board while I was typing.)

I believe it is a design choice, and not a requirement. But I am sure everyone will agree that there is no single sentence in the NEC that explicitly states, for any facility (e.g., residential or commercial), that you may not put more than XXX outlets on a YYY amp circuit. I view article 220 as having nothing to do with the design of branch circuits, but rather is only concerned with calculation of load. In order to reach the conclusion that the NEC has a limit of this nature, you have to put several articles together. I do not believe that was the way the code authors intended us to discern their intended requirements.

 

[finhead]

Charlie

I have never heard this opinion expressed before; what an interesting observation. I completely agree.

Brian Dolan

 

[rasmithircgov]

I agree with Charlie b. The code doesnt state how many can be put on the circuit. I believe this also is because there general. We dont know whats going to be plugged in to what circuit for how long and at what wattage unless is dedicated or a dedicated circuit right?

 

[bkludecke]

OK I'm listening - please explain how if the load of a recept outlet is calc'd @ 180va that one can put more than 13 on a 20. I'm not argueing, I'm intrigued and I'm learning. My guess is that it is the same idea as the range circuit thread?

 

[raider1]

210.19(A)(1) states "Branch-circuit conductors shall have an ampacity not less than the maximum load to be served."

How do we figure the "maximum load to be served"?

220.10 states "Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.16."

220.14 states "in all occupancies, the minimum load for each gereral-use receptacle and outlets not used for general illumination shall not be less than that calculated in 220.14(A) through (L) the loads shown being based on nominal branch-circuit voltages."

So if I have a branch-circuit that has only gereral-use receptacles that have no specific loads I must calculate the branch-circuit load in accordance with 220.14(I) which states that each receptacle outlet be caluclated at not less than 180 volt-amperes.

Chris

 

[charlie b]

I know that is the logic, Chris. But I am not prepared to endorse it. As I implied earlier, this is a matter of some debate. And I don't want to rehash the debate here, for fear of taking over the original topic.

If you wish to use some part of 220 as the basis for designing (i.e., calculating the load on) a branch circuit, you are welcome to do so. But I see no direct connection between 210 and 220. For example, 210.19(A)(1) does not say that you MUST use the methods of 220 to calculate the load on the branch circuit you are now designing. You may certainly do so, but nothing commands you to do so, and nothing forbids me from doing it some other way.

 

[raider1]

And I don't want to rehash the debate here, for fear of taking over the original topic.

Agreed, this topic has been hashed and rehashed before. I doubt that either one of us will change the others mind with a new debate.

Chris

 

[rasmithircgov]

Ok now Im wondering. So you calculate or are calculateing to a get a general load calculation right? So in keeping with what your saying your calculating for a circuit amount, lets say you come up with 5 cir's. Then when you wire it you dont have to adhear to any constants as far as amount of general recp's on thoses cir's. So the amount of circuits calc'd are lets say 5. Then on those 5 cir's you can put umpteen recp as long as there general. I guess I can see that because your not knowing what loads are going to be put on each recp. Correct?

 

[dnem]

And I don't want to rehash the debate here, for fear of taking over the original topic.

"fear of taking over the original topic"
I think you're talking about the original topic.

I'm familiar with the last sentence of 220.14(J) "No additional load calculations shall be required for such outlets" so the 3va per sq foot of Dwelling units on Table220.12 works out to 600sq' for 15a and 800sq' for 20a but 220.14(J) is titled "Dwelling Occupancies".

For commercial buildings you have to look back to the main paragraph of 220.14. . No matter what the requirements of 210 are, 220.14 states, "In all occupancies, the minimum load for each outlet for general-use receptacles and outlets not used for general illumination shall not be less than that calculated in 220.14(A) through (L)"

Since 220.14 says "shall not be" and 220 is just as much a part of the code as 210, why wouldn't the 180va limit of 220.14(I) or (L) apply ?

David

 

[raider1]

Ok now Im wondering. So you calculate or are calculateing to a get a general load calculation right? So in keeping with what your saying your calculating for a circuit amount, lets say you come up with 5 cir's. Then when you wire it you dont have to adhear to any constants as far as amount of general recp's on thoses cir's. So the amount of circuits calc'd are lets say 5. Then on those 5 cir's you can put umpteen recp as long as there general. I guess I can see that because your not knowing what loads are going to be put on each recp. Correct?

If you are calculating for a dwelling unit using section 220.14(J), I would say that you are correct.

But 220.14(I) is in section II for Branch-circuit Load Calculations, and as such this is dealing with the load for a single branch-circuit and each receptacle "Shall be calculated at not less than 180 volt-amperes".

Chris

 

[charlie b]

I don’t recall being a participant in the earlier debate(s) on this issue. Let me just give a vague notion of my view, and leave it there. Feel free to disagree, but I don’t intend to disagree back or to cite any supporting NEC articles.

My general notion is that 220 is fiction, and 210 is reality.

By that I mean that 220 is all about making sure the facility has enough power available from the utility (and at lower-level feeders and branch circuits) to handle the loads that the NEC authors consider to be the minimum required for a safe installation. 220 has nothing to do with the ACTUAL equipment being installed. Specifically, it does not account for the current that will be drawn by any installed component at any point in time. We are allowed, for example, to presume that all ten residents in a ten-unit apartment building will not all be running their electric ranges at high power at the same time. But in reality it might happen, especially during certain holidays. If everyone does, and if the main trips, then the residents won’t be happy. But the NEC tells us that it does not promise to make everyone happy. We don’t have to supply enough electricity to power every item in the building at the same time. That is the essence of 220.

By contrast, 210 tells us, in explicit terms, what circuits must be present, what circuits can serve only one purpose, what circuits must have GFCI or AFCI, what locations must have receptacles, and gives a host of other real life requirements. It is real stuff.

Let me address this specifically:

210.19(A)(1) states "Branch-circuit conductors shall have an ampacity not less than the maximum load TO BE SERVED." (My emphasis)

This does not talk about the calculated load. The load “to be served” is the real, actual, physical stuff that gets built. So if I put in a receptacle, what load will be served? A table lamp, perhaps, rated at 60 watts (not 180 VA)? A portable space heater, perhaps, rated at 1200 watts (not 180 VA)? A stereo that draws 1.5 amps (OK, that one is 180 VA)? We don’t know, and we can’t know, unless we are the owners of the house being built, and we have complete plans showing what will get plugged into each receptacle.

And that brings me to,

How do we figure the "maximum load to be served"?

It’s a good question and a fair question. If YOU choose to use 180 VA per receptacle, I think you will have made a good choice. But the “load to be served” is not the same as the “calculated load.” 210.19(A)(1) never points you to 220. I say again, nothing commands me to use that method. The method makes some sense, but there are no words that explicitly or implicitly require it.

If I designed my new mansion (still pending notification of having won a big lottery prize), and if I wanted a long hallway with 60 watt floor lamps on both sides every 6 feet or so, and if this hallway wound up with 24 receptacles, so that the total “load to be served” is 12 amps, I can put all 24 receptacles on the same 20 amp circuit, and you cannot tell me it violates 210.19(A)(1).

I guess that my bottom line is that if you wish to convince me that the limit is 13, then I must ask you to either show me where 210 tells me to use 220, or compose your argument without the use of 220.

 

[bkludecke]

Your new mansion will be a 1 family dwelling most likely so the 13 on a 20 wouldn't apply anyway. My new mansion will be a mud hut out in the wilderness with no utilities; I'll wire it your way anyway.

 

[celtic]

T...what is the maximum number of 120V/20A GFCI receptacels that can be put on a 20A circuit?

Don't some manufac. have a limit on this?


I have some cloudy recollection of a similar post/question....anyone remember that?

 

[bikeindy]

Don't some manufac. have a limit on this?


I have some cloudy recollection of a similar post/question....anyone remember that?

most GFCI receptacles have a Max # of receptacles that can be placed on the load side. I don't think that is the question here but that was my first thought too. I remember that post it made me look at the GFCI receptacles I use 7 max for me but I never get to that point.

 

[dnem]

most GFCI receptacles have a Max # of receptacles that can be placed on the load side. I don't think that is the question here but that was my first thought too. I remember that post it made me look at the GFCI receptacles I use 7 max for me but I never get to that point.

Maybe somebody will know what I'm half remembering and be able to fill-in the specifics into the blanks. . A couple decades ago there was a manufacturer that limited the load plugs off of their GFCIs (they called them GFIs back then) to 4 load plugs.

Their concept probably was that they would sell more GFIs because of the limit. . For example, if you wanted to put 11 plugs along the kitchen counters you could only load 8 plugs off of the 2 GFIs and would be forced to buy a 3rd GFI for the 11th plug.

Anyway, what they found out was that contractors were switching to other brands that had higher load plug number limits. . So somebody in the company said, "Uh Oh !! . That didn't work out like we planned !" . I don't remember if that manufacturer increased their load plug count or just completely eliminated it.

David

 

[dnem]

My general notion is that 220 is fiction, and 210 is reality.


By that I mean that 220 is all about making sure the facility has enough power available from the utility (and at lower-level feeders and branch circuits) to handle the loads that the NEC authors consider to be the minimum required for a safe installation. 220 has nothing to do with the ACTUAL equipment being installed. Specifically, it does not account for the current that will be drawn by any installed component at any point in time.

I agree with almost everything you've said. . I think the one that I disagree with is, "By that I mean that 220 is all about making sure the facility has enough power available from the utility" . I don't think that's all that 220 is about.

I understand why you have come to that conclusion. . When you look at the wording in 220.12 it says, "The floor area for each floor shall be calculated from the outside dimensions of the building, dwelling unit, or other area involved", which would support the concept that 220.12 is only looking at the load on the service for the lighting and not speaking about the individual loads or even the individual branch circuit loads. . According to 220.14(J), dwelling unit plugs are grouped in with 220.12 which has this general type wording that supports the point you're making.

But your point is about the whole of 220 while I think your conclusion should have been restricted to 220.12.

Other parts of 220 don't use that same language. . The opening paragraph of 220.14 uses language like, "minimum load for each outlet" which is very different from 220.12 language. And 220.14(I) & (L) don't point back to 220.12. . They stay in 220.14 and they continue with the more specific language of 220.14 which is load specific and circuit specific.

This might be a case where the difference between 220.12 and 220.14 requires an interpretation as spoken about in 90.3. . (I know just mentioning 90.3 is likely to cause an automatic anger response in certain people and I don't intend to provoke anybody. . I just saying what's coming to mind.)

David

 

[jrlipse]

The code seems very clear on installing GFCI receptacles in Residential applications, but for a commercial installation, what is the maximum number of 120V/20A GFCI receptacels that can be put on a 20A circuit? Where is this stated in the NEC? Thx.

The code says 180VA per, then it's 180VA per. 220.3(B)(9) clearly states it. If the outlet is dedicated then it's base on the amperage rating of whatever it is. NEC 2002

 

[charlie b]

. . . . 220.3(B)(9) clearly states it.

I surmise that you missed my closing comment on my earlier post, so here it is again:

I guess that my bottom line is that if you wish to convince me that the limit is 13, then I must ask you to either show me where 210 tells me to use 220, or compose your argument without the use of 220.