What's a Tap?

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Mike03a3

Mike03a3

Senior Member
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Virginia
In a discussion regarding residential branch circuits, my electrician tells me that a TAP includes lighting outlets and receptacles. His position is that every set of pigtails off a branch circuit to provide for a receptacle is a TAP, and therefore the Table at 210.24 limits a 15 or 20a residential circuit to a total of 14 outlets of all kinds.

We agree that we can't find a definition of TAP in the NEC.

I believe that there is no limit to the number of receptacles on a residential branch circuit, provided it serves only general use and lighting under 220.3(B)(10) (1), (2) & (3). which says those receptacles fall under the 3VA / sq.ft. general load calculation. Instead, I think the limit is the area that the circuit may serve, based on the 3VA rule.

I do agree with him that other branch circuits, such as the small appliance circuits, do limit the number of receptacles by requiring a calculation of 180VA per yoke.

So - What's the definition of a TAP?
and - is there a limit on the number of general use receptacles?

Let the opinions fly.
 
I had a similar question a couple months back. Someone pointed out to me that 240.2 does have a definition of "tap." It's only a "tap" if the downstream conductors are smaller than would be needed, based on the rating of the upstream overcurrent device. If you have a 20 amp breaker, and use #12 for most of the run, but then you attach a #14 pigtail to one specific load, then you have a "tap." If the pigtail is also #12, then you don't have a "tap."

I don't think the circuits your electrician described meet that definition.
 
Table 210.24 lists minimum wire sizes for taps, not the maximum number of taps that can be made. So I'm not sure how you would get a maximum number of taps from that table :?:

As Charlie explained, these aren't taps anyway. And you are correct, no limit on the number of general purpose receptacles in a dwelling.

Steve
 
210.19(A)(4)(c) is where you will find that you cannot tap a branch circuit to supply receptacles. For receptacles, a "full" size conductor for a pigtail is necessary. A 14AWG for 15 amp circuit, and a 12AWG for a 20 amp cirucuit.

I do not know why a 6 inch, 14 AWG conductor could not be used for a short tap off of a 20 amp circuit, it seems a little overkill, but that is what is says.
 
steve66 said:
Table 210.24 lists minimum wire sizes for taps, not the maximum number of taps that can be made. So I'm not sure how you would get a maximum number of taps from that table :?:

As Charlie explained, these aren't taps anyway. And you are correct, no limit on the number of general purpose receptacles in a dwelling.

Steve
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IMO The question refers to the number of opening on a general purpose/lighting branch circuit in a dwelling. I think Mike is right, in so much as, the limit is based on the square footage being served and the 3VA rule. I recall local AHJ's using a general rule of 14 opening on this type of branch circuit. Perhaps the electrician is correct on the local rules and confused on 210.24, which refers to 240.5(B)(2) requirements for conductors size on "Taps" in a 15-50A branch circuit.


By the way, I tried to quote Steve's comment about no limit of receptacles in a dwelling. And ask if he meant to say no limit to the number of these openings on a branch circuit?
 
There is no limit to the number of receptacles you may have on a residential general purpose branch circuit.

I don't see how 210.24 can in any way limit how many lighting or receptacle outlets you can have on a circuit. That table is telling you about required wire sizes for circuits. It does refer you to 210.23 which does spell out some rules on circuit loading but it does not give any limit other than overloading the circuit.
 
Yes, I did mean to say no limit on the number of receptacles on a branch circuit in a dweling.

Steve
 
Granted nowhere in the NEC does it state the number of receptacles on a branch circuit, but that doesn't mean the number is unlimited. 220.14(J) says we include these receptacles in the "general lighting load calculations". The square footage of a dwelling is going to determine the number of general lighting load branch circuits required. The receptacles are always divided equally among these branch circuits. Most local AHJ's have their rules on number of openings on a general lighting load branch circuit. It's a common sense thing, which is required when using the NEC.
 
colosparker said:
The square footage of a dwelling is going to determine the number of general lighting load branch circuits required. The receptacles are always divided equally among these branch circuits. Most local AHJ's have their rules on number of openings on a general lighting load branch circuit. It's a common sense thing, which is required when using the NEC.
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The receptacles are not always divided equally, the code says the loads shall be evenly proportioned among branch circuits - 210.11(B).

Who knows what load is going to be connected to the receptacle when wiring a building???
The spacing required by code for dwelling units does not mean that each receptacle will be used, in my experience, there are many receptacles in dwellings that never see a prong from an attachment plug. That is one of the reasons there is no restriction to the number of receptacles on a circuit in dwelling units. Another reason is the breaker will trip if there is too much of a load- just what the code is looking for.... then it becomes a design issue.

There is no common sense that can be applied to receptacles in dwellings, as each homeowner uses the space so differently, what can one expect...
 
Pierre,

Again, I am speaking of the branch circuit, which has both receptacle and lighting loads in a dwelling. Most AHJ's have rules on the number of openings ie. receptacles, lights, which are allowed on any aforementioned branch circuit in a dwelling. In a practical sense, when you are wiring a dwelling it makes sense to divide the receptacles and lights evenly along the circuit. The AHJ has the authority to approve an installation.

If I am wiring a 35,000 square foot home in Fort Worth, Texas and I put all 350 receptacles on one branch circuit. There's a strong possibility that the AHJ is not going to approve the installation. I could argue that it doesn't say anywhere in the NEC that there is a limit to the number of receptacles on this type of branch circuit in a dwelling. To which I am sure he/she will point out Article 100 Definitions, Authority Having Jurisdiction. He/She would probably also point out Article 90.1(C) and 90.4. If I am lucky the AHJ might even point out the FPN that deals with voltage drop, which although not Code, it is something to consider when wiring a home for a consumer (see 90.1(A)).

After all that said, I still say there is a limit to the number of receptacles on a branch circuit in a dwelling. There may be no absolute number, but there is a limit. Just ask your local AHJ :wink:
 
colosparker said:
Pierre,

Again, I am speaking of the branch circuit, which has both receptacle and lighting loads in a dwelling. Most AHJ's have rules on the number of openings ie. receptacles, lights, which are allowed on any aforementioned branch circuit in a dwelling. In a practical sense, when you are wiring a dwelling it makes sense to divide the receptacles and lights evenly along the circuit. The AHJ has the authority to approve an installation.

If I am wiring a 35,000 square foot home in Fort Worth, Texas and I put all 350 receptacles on one branch circuit. There's a strong possibility that the AHJ is not going to approve the installation. I could argue that it doesn't say anywhere in the NEC that there is a limit to the number of receptacles on this type of branch circuit in a dwelling. To which I am sure he/she will point out Article 100 Definitions, Authority Having Jurisdiction. He/She would probably also point out Article 90.1(C) and 90.4. If I am lucky the AHJ might even point out the FPN that deals with voltage drop, which although not Code, it is something to consider when wiring a home for a consumer (see 90.1(A)).

After all that said, I still say there is a limit to the number of receptacles on a branch circuit in a dwelling. There may be no absolute number, but there is a limit. Just ask your local AHJ :wink:
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colosparker,

Local jurisdictions aside, if we are talking strictly NEC and what is in the book (or CD), I don't believe there is any limit on the number of receptacles on a branch circuit in a dwelling for all the reasons already mentioned. What you have outlined above, IMO, are all design issues and common sense, and not what is written in the NEC. :)
 
Wirenut,

For the sake of argument, show me where in the National Electrical Code it states the number of receptacles on a branch circuit in a dwelling is "unlimited". It's all semantics. You assume because it doesn't say there is a limit, that makes it unlimited. I say that the AHJ has the authority through the wording of the NEC to set the limits. The NEC is not all black and white that's why it is only usefull when applied by a governing body such as an AHJ. The NEC gives the AHJ the right to appprove installations, thusly you can say the limit set by the local AHJ is written into the NEC.

This has nothing to do with design IMO.
 
colosparker said:
Wirenut,

For the sake of argument, show me where in the National Electrical Code it states the number of receptacles on a branch circuit in a dwelling is "unlimited". It's all semantics. You assume because it doesn't say there is a limit, that makes it unlimited.
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How about showing us where it is limited? :?:
 
Electricmanscott,

I have cited numerous Code references. Now show me where in NEC it says the number of receptacles on a branch circuit in a dwelling is "unlimited".?? Without actual wording as such, I would assume it's up to the AHJ. Wouldn't you?
 
Without actual wording as such, I would assume it's up to the AHJ. Wouldn't you
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In most cases like this it isn't worth the fight, but the AHJ is not the Supreme Allmighty. The arguement of number of receptacle outlets limited on a branch circuit in a dwelling could be won in a courtroom based on written code in the NEC , provided that the NEC has been adopted in the area without any local amendments to the contrary.
 
Colosparker
1. No electrical inspector can set his/her own requirements. They will have to follow whatever writen code they happen to be referencing. 90.4 does not give the inspector the right to change a code requirement at his/her will.

Try 220.14(J)(1) is the reference that you have can start at, as has been said, the NEC is a permissive document and there are no sections that prohibit the number of receptacles per branch circuit in regards to dwelling units.
 
Pierre,

I agree with your statement that "no electrical inspector can set his/her own requirements." I am not referring to the electrical inspector. I am referring to the Authority Having Jurisdiction. They can and do set their own requirements. I have worked in many jurisdictions where they have adopted their own set of requirements above and beyond the requirements in the NEC. This is fairly common.

IMO 220.14(J) says we include the "outlets" (receptacles) in the "general lighting load calculation". It does not say the number of receptacles is unlimited in a dwelling, hotel or a motel. In fact, the assumption that it is included in a general lighting load calculation for this type of branch cicuit , should tell you that there is a limit. We do a general lighting load calculation to determine the number of branch circuits required per the square footage. Most AHJ's want to see the openings (outlets) evenly divided along this branch circuit. I seriously doubt an AHJ is going to allow one branch circuit for an unlimited number of receptacles in a dwelling, hotel or motel.

IMO 90.4 does give the AHJ the right to change the Code requirements as it applies to an installation. An AHJ can grant special permission to the Code, and they can waive certain requirements of the Code.

IMO 90.4 also gives the AHJ the responsibility for making interpretations of the rules as they apply to the Code. And that's the bottom line (of course you can always appeal) :wink:
 
pierre said:
Colosparker
1. No electrical inspector can set his/her own requirements. They will have to follow whatever writen code they happen to be referencing. 90.4 does not give the inspector the right to change a code requirement at his/her will.

Try 220.14(J)(1) is the reference that you have can start at, as has been said, the NEC is a permissive document and there are no sections that prohibit the number of receptacles per branch circuit in regards to dwelling units.
Click to expand...

Exactly! If it does not say you can't, then you can in most cases, this being one of them. There is nothing that specifically addresses the maximum number of receptacles on a dwelling branch circuit.

I think your argument of using 220.14(J) and the 3 VA/SF as a ceiling for the number of receptacles is flawed because that is a minimum requirement, and not a maximum as stated in 220.3(A). Also, as has been stated, how do you know what the load is going to be for any given receptacle:?:

There are references to minimum numbers of branch circuits and to adequately handle the load calculated in Article 220 and for cooking appliances, etc, and a minimum number of receptacles that must be installed in Article 210.50. Beyond the minimum requirements of the NEC, it is a design issue and what the customer wants to pay for (or local requirements).
Just my opinion :D
 
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