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Joined: Aug 2011
Posts: 2
New Member
Hi all.

This is a question particularly to New Zealand and maybe Australian electricians.

I am told, by more than 3 different registered electricians that the maximum number of 10A single outlets on a standard power circuit in a domestic installation is 12, that is 6 double outlets on a 20A breaker and 2.5mm cable. They assure me this is the law but cannot tell me where it is dictated.

When I look up the Wiring Rules (AS/NZS3000:2007 amendment 1, Sect C5.2 and Table C8), it indicates an allowance of 1A per outlet allowing a max of 20 singles or 10 doubles?

Even this table is titled "Guidance on..." So it sounds to me that this is a rule of thumb and the maximum outlets on a circuit should be determined by the installation and likely usage of appliances on the circuit so as to prevent nuisance tripping of the breaker as opposed to being the law?

In the notes section for table C8, note "i" states "The values are intended to be utilized when the final subcircuit is provided for general use. Where it is known that socket-outlets may be used for specific items of electrical equipment, such as dishwashers, room heaters or clothesdryers, the actual load of the equipment should be substituted."

I am an apprentice attempting to learn and adopt best practice. Have I answered my own question here? Many thanks!

Joined: Jul 2002
Posts: 8,407
Likes: 2
Hey man,
Welcome to ECN!!
Good to see another Kiwi find their way here. wink
This socket-outlet thing has been going on for some years.
One guy that I did my time under once told me, that there is no limit on the number of outlets you can have on one circuit, with a circuit breaker on it.
This sort of attitude is just plain wrong and only ends in tears when there is nuisance tripping of the breaker, caused by poor design of the installation.

Now, I don't have a copy of the latest Wiring Rules at home here (it's on a shelf at work).
I think what you are looking at though is the maximum demand tables, used for working out total connected load.
The allowance of 1A per socket-outlet works on what is known as diversity, in that not ALL of the socket-outlets on that circuit are going to be used at the same time, unless you're really tight with the number of sockets you install, in a given area.

This is somewhat different though to the actual planning of working out how many sockets you are going to have on a given circuit, this varies with each individual installation and it's layout of rooms, etc.

And personally I'd NEVER go with the set-up the Architect has shown on his plans, I've never seen anything remotely realistic in the time I've been working off plans.

What has also "muddied the waters" so to speak, is the fact, that some electricians also use 1.5mm˛ on a 16A breaker for some shorter runs.

I hope that this post has been of some use to you, if not, please by all means, let me know.

Mike. cool

Joined: Apr 2002
Posts: 7,279
Likes: 3
Just an FYI for my friends in Nz; it's basically the same here in the states.

Joined: Aug 2011
Posts: 2
New Member
Thanks Mike,

I really appreciate your time to respond.

Yes, I understand. A lot of this is common sense and I am definitely one who likes to use my head!

I am currently working part-time for two different electricians with different focuses and "standards". Trying to establish my own best practices in amongst the pressures of differing businesses and keep the boss(es) happy.

Keeping it safe and sensible (along with within the "law" as in the past I have found that the law is not always sensible).

I'm loving the learning.


Joined: Jul 2002
Posts: 8,407
Likes: 2
Hey not a problem at all, Pete.

It sounds like you've got the right sort of attitude for an apprentice electrician.
I've always felt that the time during your apprenticeship is probably the most important time of your entire career, as this is the time where you learn the fundamentals of the trade.

Best of luck with you apprenticeship, I hope it goes well and by all means, if you have a question, don't be afraid to tap out a thread here, we don't bite. grin

Joined: Mar 2007
Posts: 101
Actually 220.14 (I) states 180 VA . This means 120V times 15A divided by 180 VA equals 10. That is 10 receptacles on a normal 15 A circuit. Where as 120V times 20A divided by 180VA equals 13. This is in 2011 NEC.

Joined: Mar 2011
Posts: 98
Originally Posted by mikethebull
Actually 220.14 (I) states 180 VA . This means 120V times 15A divided by 180 VA equals 10. That is 10 receptacles on a normal 15 A circuit. Where as 120V times 20A divided by 180VA equals 13. This is in 2011 NEC.

Mike, you did notice that this is the NON-US section right?

Also, you can't load the 15 and 20 amp circuits beyond 80% unless the OCP is fully rated so you are limited to 12 amps on the 15 amp circuit or 8 receptacles and 16 amps on the 20 amp circuit or 10 receptacles.

If the circuits are for residential general illumination then there is no limitation on the number of receptacles though common sense should come into the equation, but all of this only applies where the NEC is enforced though which is not within this section of the forum.

Joined: Mar 2005
Posts: 1,803
In the UK you can have as many receptacles on a British ring-main as you like, within breaker limits, because every recept has its own 13A or 5A fuse. I've seen houses with 20 in one kitchen alone, singles, doubles, triples, quads all strung to a 25A breaker! Modern use means that few recepts ever draw more than a few amps consecutive, most less than an amp @ 230v for the phones, wall warts, computers, gizmos etc.. The most power my son in England ever draws is 4A for the vacuum.

Wood work but can't!
Joined: Jun 2006
Posts: 613
Canada sets the demand for a duplex outlet at 1 amp so 12 for a 15 or 20 amp circuit as the maximum number is 12 unless the load is fixed and known. For example you use plugs and receptacles for lighting Each luminaire is .25 amps so if each duplex is loade to .5 amps you could go to 24 duplex outlets on a 15 amp circuit loaded to %80.

Joined: Oct 2005
Posts: 19
Originally Posted by Alan Belson
In the UK you can have as many receptacles on a British ring-main as you like, within breaker limits, because every recept has its own 13A or 5A fuse.

Ordinary receptacles (sockets) are not fused, but the plugs are, to protect the appliance cord. This is necessary because ring circuits (and some radial circuits) are protected at 30A fuse or 32A breaker, but an appliance such as a table lamp may need to be protected at 3A.

Only single or double outlets are connected to ring or radial circuits; triple or quad outlets will have an integral 13A fuse to prevent overloading as they're internally only rated at 13A.

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