Can anybody reference in the NEC where it says how many receptacles are allowed on a branch circuit. Our general rule of thumb here in PA is 7 per circuit. However the debate is ongoing at the local electrical distributor/coffee shop. (As I am sure that everyone experiences.)

If you're talking about residential, there is no NEC limit. I've always followed the common sense rule of 8 on a 15A circuit and 10 on a 20A circuit in residential. It gives you room to add on to a circuit later. If it's a commercial setting you would figure 180VA per so it would be 10 on a 15A @ 120V and 12 on a 20A @ 120V

I agree with you on both issues. We here in PA dont understand how an inspector can not pass an installation stating that there are too many recepts on a circuit since the code does not specify it. Is this left up to the inspector and his interpretation?

Blue,

If he can't write down or tell you the code section, it isn't a violation. Inspectors aren't allowed to make up their own rules. If the NEC is adopted by law or ardinance, any exceptions or additions must also be enacted by a legislative body.

Per code- residential, as many as you want, Commercial- 10 on a 15 amp circuit, 13 on a 20 amp circuit.

I would agree with Tom, however, with one added note. Since, per 220.3(B)(10), the load calculations of general-use receptacle outlets for dwelling units are included in the general lighting load calculations from table 220.3(A), which is based on 3VA per sq. ft. The load (number of receptacles) shall be evenly proportioned among the multioutlet branch circuits within the panelboard, per 210.11(B). So if you had a branch circuit that was not evenly proportioned as compared to the other receptacle outlet branch circuits in the panelboard, the inspector would be correct in not passing the installation.

mdsmith

what if you wired receptacle circuits exclusive from lighting circuits....

just a wha-if..

The number of receptacles on a general purpose lighting circuit in a house doesn't have much to do with evenly proportioning the load. This was already taken care of in the watts per square foot calculation and the calculation to determine the minimum number of circuits that are needed. Since receptacles are not a load, there is no limit to how many on a general purpose lighting circuit. If an inspector tried to cite me on not balancing the load because one circuit had many more receptacles than another, we'd be into the appeal process in short order.

Tom

My sentiments exactly. I do a lot more light industrial and commercial work than residential, so my my code knowledge is more geared toward to those areas. This came up on a house addition in which the inspector would not pass the rough-in until 1 receptacle was removed from the circuit. The "show me the code" attitude came into play and another inspector was called who subsequently passed the installation.

As many of you know, I am an electrical designer, industrial/commercial mostly. We usually do not load our circuits to over 80% unless the breaker is rated for 100% load. Most panelboard breakers are not 100% rated. Therefore, on a 20 amp breaker, we use 20*120*.8=1920watts per circuit as the maximum, which equals 10.(66) receptacles. Normally we use seven (7) as our target loading . This is for commercial/industrial work. In many areas of commercial/industrial work, you have to consider the receptacle as having a computer (300 watts) and a printer HP= ~10amps). That means one (1) circuit per receptacle, unless you can come up with a printer demand factor. We usually use two and no more than three recptacles per 20 amp circuit for these applications. This will happens in office areas where every occupant wants a printer. In my office, we have one printer for about 30 persons. Needless to say, most are on a branch circuit to themselves because of high demand.
For residential, my code instructor taught us there is no limit to the number of recptacles on a branch circuit. However, with the increased use of computers (and severs)in the home, I believe that should change in the very near future. Everyone has to have access to the NET to check their email.
Just another thought on this subject.

sparky,

My reference to 220.3(B)(10) and table 220.3(A) was not to imply that general-use receptacles would necessarily have to be wired to lighting circuits for the provisions of 210.11(B) to apply, but that since the outlets specified in 220.3(B)(10), (1), (2), and (3) are included in the sq. ft. general lighting load calculations of 220.3(A) the provisions of 210.11(B) would, in fact, apply regardless. Great discussion!

Indeed a good thread

mdsmith,
i just wished for points of view, there are many romex jockies that seperate lighting for the genny interface

I,m not an electrician just an maintance guy building a house. Trying to figure my circuits. On a 15 amp circuit roughly 1440 watt max. On a 20 amp 1920 watts max. keep light and plug seperate due to if one blows not left in dark. How many watts is a ceiling fan, refrigerator, dishwasher. Can I run the whole house as a 20 amp 12 ga wire. Why must I used 14 ga 15 amp. Does GFI need own circuit or can I branch.. I got a friend that works for the power company that will do the job, I.m just trying to understand some of it.

brownbag,
just keep readin' here....

I dont think that I realized the far reaching effects my orginal question has on most of the wiring that is done. It seems to me that some thing this big, that affects a design so much, should be reference and defined in the code with a clear and concise section. Any takers on that?

The NEC does not deal with design issues (supposedly). On that basis, you shouldn't expect the code to change.

As far as residential wiring is concerned, if you could show how this is a safety related issue, keeping in mind that there are many years of experiance dealing with house wiring in the code, then you would have some basis for getting this changed in the NEC. I don't think it is any big deal.

Housewiring is such a cut-throat business, those that do it usually have to stick to the bare minimum in order to get the job, otherwise they'd price themselves out of the market.

Just for grins , why don't you submit a proposal for the 2005 NEC?

I'm confused. Some of you are saying 10 receptacles on a 20 amp circuit and some are saying 13 (in commercial occupancies). 1999 NEC table 220-13 shows that the first 10 kVA may be calculated at 100% which would allow 13 receptacles on a 20 amp circuit. 220-21(b)(2) requires that the maximum cord and plug connected load on a 20 amp circuit to be no more than 16 amps, which is 80%. This would allow 10 receptacles on a 20 amp circuit. It seems to me that these two references are in conflict with other. Can anyone clarify this for me? (By the way, most of the local inspectors in my area ask for no more than 7 receptacles on one 20 amp circuit.) As usual this is a great discussion. Even with almost 30 years in the trade I learn something here almost every day.

WireWrestler,

ref: 1999 NEC

Table 220-13 is demand factors the code allows to be applied in sizing feeders and or services for nondwelling receptacle loads, not for determining the number of receptacles per branch circuit. For this, you need to look at 220-3(b)(9), (the handbook has an excellent explanation of the article). Use 180VA per strap > 180VA/120V=1.5A per strap > 20A/1.5A per strap = 13.333 straps > 13 straps or devices.

Article 210-21(b)(2), the way I read it, is for the maximum cord-and plug-connected load for each receptacle, (not branch circuit), where the branch circuit has more than one receptacle on it. We as designers and installers lack control in meeting this requirement. It seems to me, this would be imposed on the building occupants after the installation is complete and in use.

[This message has been edited by mdsmith (edited 01-08-2002).]

The is an alleged rationale behind most codes. I don't know how old 220.3(b)(10) is. My gut is that a few extra residential receptacles vs. extention cords was, at one time, the intent.

mdsmith
Thanks, the muddy water is getting clearer.
WireWrestler

With regards to the number of duplexes for residential,I would check with the local authority or who ever issued the permit.Many times these local authorities have supplements to the NEC that are enforced.Also check to see what year of the NEC they are using.

Chris