How many socket outlets on a radial circuit

Discussion in 'Electricians' Talk' started by celconman, Apr 3, 2006.

  1. sim

    sim Member

    Ah, the point I made wasn't as clear as it could be,

    I was just making the point that if you 'retro-fit' a
    return leg on what was a radial to make it a ring,
    you'll end up with an uneven distrubution of outlets
    around the ring, making it prone to becomming

    whats mickey mouse about radial power circuits? ,ring
    circuits would be more mickey mouse in my opinion a
    strange design compromise that only we British use

    I can understand where you are coming from, however... the pic that you present doesn't show the length of the circut, and in reality, how many residential buildings have you been to that have only sockets on one ( linear ) section of a wall, Ie, just on one side of the building....?
  2. gaz58

    gaz58 New Member


    Have you got over 50sqM? If not then your radial is quite adequate providing it has the correct protective device and does not exceed the length for the volt drop.
    A 20 Amp breaker would normally suffice with 2.5mm2 but you have to be careful about correction factors for insulation, ambient etc. If you have rooms above a garage for instance with a lot of insulation in the floor space then its quite possible you might need a 16 or even a 10A.
    I personally have no preference for rings or radials but as a previous poster said if the design is done right then both types are ok.
  3. JP.

    JP. Screwfix Select

    With all due respect can someone please explain how on earth a radial supply feeding multiple sockets is better then a ring circuit doing the same. Lets face facts. 1 Any breach in the earthing line in radial circuits will leave any sockets upstream unearthed ( RCD even though of course used is irrelevent) unless the end of line on the radial has an earth flyer taken back to the cu etc. ( Obviously with the ring circuit a breach will still leave protection if the earth has been wired correctly in the socket) 2 You are limited to 20 amps on 2.5mm and if you want 32 amps you have to honk in 4.0 mm. 3 You are highly limited on 2.5mm radials on to how much you can load it. Say your heating breaks down and its freezing cold and you want a couple of fan heaters on the 2.5mm radial you cant the breaker will trip. Radial circuits in my mind are a retrograde idea in the design of socket outlets in rooms etc. (I am not talking about dedicated radials to immersion heaters etc) and as such I stand by my thinking on radial circuits and am certainly not interested in what other country wiring techniques are used unless I can see logic in there ideas/wiring practices etc. JP.
  4. JP.

    JP. Screwfix Select

    Any replies on this. JP.
  5. JP.

    JP. Screwfix Select

    No thoughts anyone. I think this is a very relevant subject.
  6. steve .w

    steve .w New Member

    Lets face facts any break in either phase of a ring maincould also be risky.I personally do not like ring mains and use radials where possible easier to install and safer in my opinion
  7. gaz58

    gaz58 New Member

    B####r. you beat me to it on 1

    2. 32A is not a target that always has to be achieved. If the design of the circuit only requires 20A and thats probably more than enough for the poster,s situation then its fine.

    3.A 20A radial will supply 4.6Kw constantly. Thats enough to supply 2X2kw heaters no problem.

    Radial circuits are a retrograde idea, they've been around for a lot longer than ring circuits and perfectly good practice where required.
  8. steve .w

    steve .w New Member

    I agree totally on those two points gaz.I started sparking in 1969 and was brought up on ring mains but i now see radials as a good modern practice when installed correctly
  9. JP.

    JP. Screwfix Select

    Ive pondered over this and there is no way that I can see that radial circuits are better or safer then ring circuits. If I was going to rewire a three bed house say in the radial way I would need a consumer unit with a lot more ways and it would also hinder the way I designed the rewire. With all the regs out now why is a radial circuit not required to have an earth flyer of the end of the last socket back to the cu. Again I say if you get an earth breach on a ring it is supported both sides, on a radial it is not. ( I know it is RCD protected but that is immaterial to the design). I for one cannot see why people advocate the idea on the use of radial circuits. ( Immersion heaters and dedicated items which use radials excepted). Anyway thanks for your input on this. JP.
  10. steve .w

    steve .w New Member

    I cannot understand your point,firstly most cu are 12 way plenty to spare when you only require one more way,secondly what if your earth comes away in your FCU thirdly,whats the point of a return earth on a radial if the earth breaks on the last socket.There are lots of if's and but's in any design
  11. andyspark

    andyspark Active Member

    Absolutely nothing wrong with an installation that uses 20A radial circuits for the sockets. Or even a mix of radials and rings all correctly marked up at the CU.
    Much more practical for isolation purposes. Individual rooms or groups of rooms can be isolated conveniently.

    As stated; design the installation, don't follow like sheep.
  12. plastic bertrand

    plastic bertrand Active Member

    steve w wins the argument for me
  13. Smigga

    Smigga New Member

    I re-wired an extension last year that was unfusespured of the house ring, it fed the extension that was used as a utility room it was running an iron, washer, drier lights and 2 spare sockets, it was used most days and had been like that for 15 years. There was no noticeable heat damage to the 2.5 used and e/loops were fine out of interest before it was ripped out.
    How many of us have found an fcu feeding umpteen sockets with no problems. I think some people worry to much and do to little.;)
    I see no problem in using 16A radials if you can do so safely, I agree that they make isolation easier and disruption less when changing sockets etc.
  14. gaz58

    gaz58 New Member

    "I think some people worry to much and do to little"

    Agreed. People read too much into everything. And I agree with the statement made on this forum tonight that since part P everyones now an expert even if they admit they are not qualified. I served a excellent four year electrical apprenticeship but not as a spark, was S/E 3 years late eighties as a domestic/commercial contractor (some learning curve that!) have 2381,hope to have 2391 results shortly and still find it hard to call myself an electrician without 2360/2330 etc. I took the EAL as a refresher last year and it was a load of bo l l ocks but now people are doing this **** and calling themselves electricians. Everyone on that course without electrical knowledge would have failed if it wasn,t for the multiple choice that you get as many goes at until you get it right.

    Rant over
  15. mr bojangles

    mr bojangles Member

  16. Adam_151

    Adam_151 New Member

    Duly noted
  17. celconman

    celconman New Member

    Thanks for the information everyone, in particular I would like to reply to the following posts:- ADAM51 POST146; thankyou for this link which clearly illustrates your point about an unbalanced circuit.; JPPOST Post44; I thought that a 2 socket radial was usually described as a spur- usually fused?. Also, are you saying Brian Scadden is wrong?. GAZ58, POST105; I have 42 sq metres, the CU has a 40A 30ma RCD, one 20A MCB and a 6A MCB.THe circuit runs partially in a floor void, mainly chased into walls and running under floors at doorways.Thanks also to Andyspark,Plastic Bertrand, Smigga and Gaz 58, although all posts collectively have been helpful. All I need to do now is find a leccy who is happy with a radial circuit!
  18. JP.

    JP. Screwfix Select

    Hello everyone. Firstly the quality of input on this has been excellent and for me this is gold dust. Again I have had a good in depth think on this and yes I can see the benefits of radial circuits in particular with regards to neatness and the need to not bring a leg back to the cu which obviously makes it much easier to split your circuits with regard to different rooms which in the end will not clag up the cu with . However I still could not bring myself to wire up the kitchen with a sole radial circuit but thats just me. ( I do not mean dedicated radials to fridge/ freezer/ washing machine etc). Just a very basic questions. Is it okay to run your radial legs through one joist hole ( Air gap noted) a stupid question I know but already I can see how much neater it would be with regards to running rooms from a central branch hole rather then worrying about return legs through the same hole/holes etc. Also I believe you are not limited to the amount of sockets you can use on the radial ( within reason) the reason I say this is that when you know where you are going to place your tv/av system etc a minium of three double sockets to feed it it is in order (using 4 way adapters etc would make it a very bad design) so there goes three doubles minimum. Once again the quality of input on this has been excellent and thanks to everyone who put across their opinions. JP.
  19. plastic bertrand

    plastic bertrand Active Member

    I agree with your statement JP.:)
  20. gaz58

    gaz58 New Member

    I would always use a ring to feed a kitchen, 20A is just not enough for this situation. I would also probably employ 3 rings in your average house, up/down/kitchen. All I am saying is that radials are good practice where the situation allows and in the case of the poster (2 bed/2bath extension) it is quite adequate.

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