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Strange Radial Circuits?

Discussion in 'Electrics Outside of the UK' started by LostInDiy, 12 Jan 2011.

  1. LostInDiy

    LostInDiy

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    Hi,
    In my parents house in Ireland, which was originally wired during the mid 1970's, I notice that some of the socket radial circuits come out from the 20A MCB via 2.5t&e to a junction box in the attic. Two or more seperate feeds then go from this box via 2.5t&e to an individual socket.

    This looks strange to me as most modern radials are daisy chained from socket to socket. Is this still allowed in the latest regulations?

    Also in some cases, additional sockets have been added at a later date by connecting in from the back of some of the existing socket.

    The light circuits follows a similar pattern with 1.5mm singles each going to an individual junction box and from there on to the various light switches. The neutrals for that circuit all return to a junction box and return via a 1.5mm single to the consumer unit.

    Just want to check that these are still safe as the circuits proabably have a lot more load now that when originally installed in the 70's, and also a good few modifications.

    The consumer unit was updated some years ago and has an RCD on all the sockets.

    Whats the verdict?? :?:
     
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  3. 1john

    1john

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    If the junction boxes are accessable then this is all ok.
     
  4. solair

    solair

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    The original wiring that you are describing is quite normal in Ireland and elsewhere i.e. using junction boxes.

    There's nothing unsafe about it. In fact, some people would argue that it's safer than running long daisy chains as you are not using socket terminals as junction boxes. Instead, you're using junction boxes, which are actually designed to make multiple connections.

    The maximum number of connections allowed to a single radial circuit in Ireland is 10 sockets (single or double) serving a maximum of 2 rooms (excluding hallways which are assumed to be low load anyway)

    Typically you'll find 1 x 20A radial for each of the bigger rooms in the house i.e. the living room etc, and then you may find that 2 bedrooms share 1 X 20A radial. It depends on the number of sockets and what the envisaged load was. Hallways may have sockets that are just on the nearest radial.

    The kitchen will typically have 2 or more radials e.g. one serving general sockets, another serving the washing machine / dishwasher, maybe another to the laundry room (sometimes 2 depending on the load). Our utility room has 3 X 20A radials each serving a double socket.

    The same applies to lighting circuits.

    The wiring you are describing is absolutely normal i.e. singles and junction boxes with a common neutral for lighting.

    Again, junction boxes are normally used extensively in Irish wiring, particularly older wiring. It is much closer to Northern European continental wiring than it is to British wiring in many respects i.e. in general rings are not all that widespread in Ireland, radials are preferred.

    There's definitely nothing in the Irish regulations that would insist that you daisy-chain sockets.

    You might want to check that the DIY work was done correctly, but the original wiring sounds fine.

    Usually, spurs/branches are more of an issue on rings than radials to be honest.

    Irish Regulations on rings are a bit different to the UK.

    1) No rings in kitchens. At least 2 radials must be provided.
    2) No spur sockets off rings (at all).
     
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  5. fidom

    fidom

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    I thought 2.5 was for ring mains and that radials were wired in 4mm? Or is the 2.5 only from the junction boxes with thicker stuff feeding them? :confused:
     
  6. solair

    solair

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    4.0mm2 would apply to 32amp radials.

    Radials in Ireland are fused at 16amp or 20amp, similar to continental Europe.

    Ireland originally used 16A radials and German-style Schuko sockets. These were replaced by BS1363 13A fused plugs and sockets in the 1960s and 1970s but the Northern European style 16amp or 20amp radial wiring methodology remained in place.

    I always got the impression that Irish electricians were a little skeptical about the safety margins on ring circuits.

    We also never used UK-style fusing. Instead, we've always used German-style diazed and neozed fuses on consumer units installed before the MCBs were introduced.

    While ring circuits are allowed in Ireland (other than in Kitchens) they remain relatively unusual. Where as in the UK they're used by default.

    Basically, think of the Irish system as being more like German or French distribution systems with UK sockets.
     
  7. fidom

    fidom

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    Interesting. I have been to Ireland once but must have not taken any notice of the sockets, consumer units etc. I had just assumed they would have followed UK practice.
     
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  9. solair

    solair

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    Generally, it's a bit of a hybrid of UK and Continental methodologies with some locally developed norms too.

    The power supply here was 220V 50hz (single phase) and 380V 50hz (3 phase) until the whole of Europe re-standardised to accommodate the UK's 240/415V system i.e. we all moved to 230/400V.

    The wall fittings i.e. sockets, switches etc are UK-style but the consumer units are quite different beasts. Although, with European harmonisation, UK consumer units are much closer to normal these days too.

    For example, in my house here's what you have:

    Under the rules when my home was wired, general lighting and cookers did not require RCD protection.
    All sockets have required RCD protection since the late 1970s.
    Bathroom lighting also requires RCD protection.

    Power company equipment:
    [Line] ---- [Supply fuse + bonds between supply neutral and my local earth] ----[meter]-----[rotary isolating switch operated by key] ----- (consumer's equipment connected here and contractor turns key and seals).

    Consumer unit:
    [80 amp main fuse [minized fuse switch that looks like a breaker] ----

    All of these are RCD protected with an RCD on each row:
    Kitchen sockets 1 (20 A radial)
    Kitchen sockets 2 (20 A radial)
    Utility room sockets 1 (20A radial)
    Utility room sockets 2 (20A radial)
    Living room sockets (20A radial)
    Dining room sockets (20A radial) (also covers hallway)
    Bedroom 1 & 2 sockets (20A radial)
    Bedroom 3 + hallways (20A radial)
    Master bedroom (20A radial)
    Central heating (16A radial)
    Alarm system (6A radial)
    Bathroom lighting (10A radial)
    Attic sockets (16A radial - supplies power to routers and various TV equipment + doorbell transformer)

    General lighting:
    Kitchen lighting - 10A radial
    Living room + dining room - 10A radial
    Hall + study - 10A radial
    Bedroom 1+2 10A radial
    Bedroom 3+4 10A radial
    Hallway + outdoors (10A radial) (RCD protected)

    High energy circuits:
    Cooker : 32A radial (not RCD protected)
    Shower : 32A radial (RCBO protected)
    Immersion : 20A radial (RCBO protected)

    Individual circuit:
    Fridge + freezer - separate RCBO protected circuit at 20A.
    Outdoor sockets - separate RCBO protected circuit at 20A.

    So, as you can see it's a bit different to the way you do things in the UK.

    Older style Irish fusebox : (The lever is an old-style RCD from the 1970s)

    [​IMG]

    Pre-dates the common use of MCBs and uses fuses that look like this [​IMG]

    Each fuse tip is a different size, getting bigger as the rating goes up, so you can't replace a small fuse with a larger one.
     
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  10. fidom

    fidom

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    Thanks for that. 10 amp seems high for lighting whilst 32 is low for a shower. Some of the electric showers I've installed have required 10mm cable and a 50 amp mcb. Others are 6mm/40amp. RCD protection is a requirement here for outside sockets and outbuildings but you can still buy a consumer unit with main switch and mcbs.
     
  11. solair

    solair

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    Shower in my house is only a secondary backup to the central heating system heated showers we don't use it much, hence its so pretty low powered model.

    They seemed to always prefer slightly higher rated lighting
    compared to the UK. It allows for future expansion and higher power lights i guess
     
  12. fidom

    fidom

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    I have one 6 amp mcb for the whole house lighting but it is only a small 2 bedroom cottage. The convention is to have an mcb for each floor.
     
  13. LostInDiy

    LostInDiy

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    Thanks all for the informative replys. A lot of questions are answered reading this. :D
     
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    DIYnot Local

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