0

like how many sockets can one have on a either ring or radial circuit planned to be protected by 20A breaker

1
  • 1
    Posting your location would be of great help. Getting code appropriate answers for the US will not help much if you are in the UK or Australia for instance. Oct 15, 2014 at 1:31

3 Answers 3

4

The number of sockets you can have connected to a circuit isn't limited by the circuit breaker's amperage. No matter how many sockets you connect, you're still limited by the 20A limit on the circuit breaker. A socket with nothing connected to it does not draw any current.

Think about what devices you want to connect to the circuit. Find out how many amps each one draws and total that up. A 20A circuit can supply 20A intermittently or about 16A continuously (load for more than 3 hours at a time). Use the total amperage you need to supply to determine the number of circuits you need.

If you wish to connect multiple devices, but not use them simultaneously, you may do so as long as they don't exceed 20A or they'll trip the breaker.

2

"Ring circuit" suggest UK or a country using similar practices and regulations.

As far as I know, BS7671 allows for (or simply suggests) up to 100 m length of T&E cable covering a floor area of up to 100 m². There is no limit to the number of sockets per ring.

Typical UK homes have one ring per floor and a separate ring for the kitchen/utility rooms.

A 20A breaker is sized to protect the cable (so depends on cable cross-sectional area, not on number of sockets, and not simply on how much current you would like to draw) The breaker limits the total current draw through appliances connected to sockets.

So you could in theory have 150 sockets with 100 mA appliances running. Or just one kettle.

In the UK, adding sockets at new locations to an existing circuit is not notifiable but adding a new circuit (ring or radial) would be notifiable under Part P - so you'd probably pay an electrician to do the work and certify it.

3
  • Thank you for considering the correct code reference according to the wording in the question. That is what I was alluding to with my comment to the question. I just did not want to assume a location, but I think you're right. Oct 15, 2014 at 11:37
  • On the other hand one of his other questions talks about a "200A main breaker" which sounds USish to me. I guess whereever he lives he has been reading websites from multiple countries without realising that practices differ. May 18, 2016 at 19:25
  • BTW on the notifiability adding new sockets to an existing circuit in the UK is not notifiable but adding a new circuit is notifiable. May 18, 2016 at 19:26
0

Just to add to what rj said...you can only utilize 80% of a breakers rating. So if you have specific uses don't exceed the 16A or add another circuit to that. But as rj said...you are not limited by the number of receptacles unless the load is known. In my exp. many people put on about 8-10 per circuit. I personally split circuits by rooms, larger rooms splitting into more than one circuit.

5
  • 1
    I wish electricians in the '60s split circuits by room. That would make my life much simpler. My advice is to keep circuits as small as reasonably possible. Separate room lighting from wall outlets.
    – rjbergen
    Oct 15, 2014 at 2:49
  • lol the first house i bought had a panel box with only 2 single pole breakers that they tied the old knob and tube onto...wasn't sure what the point was there. That was built in 1923...it was gutted and everything redone...who can live with 2 circuits in a 4 bedroom house!
    – Kevin
    Oct 15, 2014 at 2:52
  • 1
    Can you point me to this blanket 80% limitation for circuit breakers? I can't seem to find it in the NEC. Table 210.24 seems to say different. Oct 15, 2014 at 11:06
  • 1
    I don't think most folks consider receptacles "continuous" loads, so I can't understand why you'd only use 80% of the circuit.
    – Tester101
    Oct 15, 2014 at 12:14
  • If you have a branch circuit supplying nothing but “continuous loads,” then the minimum conductor size must have an ampacity of 125% of the load – 210.19(A)(1) – and the overcurrent protection must be 125% of the load – 210.20(A). Therefore, the breaker must be loaded to no more than 80% of its rating. This applies to a circuit that has a combination of continuous and noncontinuous loads. At the time of my answer the specifics had not been posted therefore it was unknown as to what was continuous or noncontinuous.
    – Kevin
    Oct 15, 2014 at 19:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.