radial circuit

eddie99 · Posted: Thu May 10, 2007 10:03 am Post Subject: radial circuit

need more sockets in property.have four separate radial circuits 1 kitchen 2 lounge&dining 3 two main bedrooms 4 two guest bedrooms and small office. all run from consumer in 6mm cable then junction boxed down to 4mm directly above consumer.each circuit runs six double sockets, need eight maybe more on each.can i junction box in 4mm for additional sockets or is this system outdated and better to replace with 2.5mm rings ? all wiring looks new in good condition and checked by meb in 2002.

JohnD · Posted: Thu May 10, 2007 10:09 am Post Subject:

could you post some pics showing the CU and wiring, meter, service head please?

eddie99 · Posted: Thu May 10, 2007 10:51 am Post Subject:

sorry john useless with technology dont know how to upload any pictures !

davy_owen_88 · Posted: Thu May 10, 2007 11:37 am Post Subject:

Am I right in assuming you mean there is a single 6mm² cable going to a junction box where all the radials come from or are there separate 6mm² cables for each junction box/radial circuit? What size fuse/MCB is this 6mm² cable connected to?

There is nothing wrong with radial circuits but the use of junction boxes should be kept to a minimum. If you can give more info on how the wiring is currently organised we might be able to offer a simple solution to your problem.

See here to upload pictures.

oharaf · Posted: Thu May 10, 2007 11:39 am Post Subject:

I would attempt to get rid of junction boxes and replace with 2.5t&E.

You can have an unlimited number of sockets on a radial as long as no appliance exceeds 20A (the OCD). This is assuming a floor area of less than 50m squared for each radial.

If you're prepared to redecorate (a little) I would go for Final Rings myself, as they are easy to extend.

For greater detail look in OSG page 151 table 8A

and page 156 gives recommended number of oulets per room

Might be worth thinking about

Do it once, leave it alone

BOL

JohnD · Posted: Thu May 10, 2007 12:13 pm Post Subject:

oharaf wrote:

...and replace with 2.5t&E.

If he runs radial circuits in 2.5,mm then he will have to fuse the entire circuit at 20A.

This will mean that the washer and drier together will exceed the design current.

That would not be a good move.

oharaf wrote:

...as long as no appliance exceeds 20A

This is factually incorrect. The limit of any single appliance on a UK fused plug is 13A.

Yes, re-wiring with rings is fine. This would be notifiable work. Not everyone finds them easy to extend properly.

dynomo · Posted: Thu May 10, 2007 1:50 pm Post Subject:

mr JohnD
There was a call out for you last night on the bathroom illuminated mirror post? was kinda looking forward to your response on it all, but hey I understand if you are a busy bee. I have noted you are a knowledgable man (read some of your responses and posts on the plumbing section), pretty impressive i must say. Keep up the good work, this site needs more individuals like you mate.

Dynomo

JohnD · Posted: Thu May 10, 2007 2:14 pm Post Subject:

there is also a John_D who knows about plumbing

dynomo · Posted: Thu May 10, 2007 4:09 pm Post Subject:

good man,
at least ur honest, unlike 'a few' others on this forum...

eddie99 · Posted: Thu May 10, 2007 8:22 pm Post Subject:

Thanks for your replys. each circuit has 6mm cable running vertically for around 2 metres then junction boxed down to 4mm under bedroom floor. why not run all in 4mm? cable then runs into each room and junction boxed off to each socket .each circuit on 32 breaker and biggest floor area covered is around 35m2. hope this makes sense !!!!!!!!! thanks

davy_owen_88 · Posted: Thu May 10, 2007 8:29 pm Post Subject:

eddie99 wrote:

then junction boxed down to 4mm under bedroom floor.

Tut tut...

Junction boxes should be accessible, so if you are doing work on the circuit you might want to get shot of them and wire each socket in a daisy chain fashion... If you are not comfortable opening up the CU then leave the 6mm² but move the junction box somewhere accessible, then go down to 4mm² cable and wire the sockets as below...

JohnD · Posted: Thu May 10, 2007 8:35 pm Post Subject:

the diagram shows 20A MCB and 2.5mm, but I don't think that's what you meant.

davy_owen_88 · Posted: Thu May 10, 2007 8:36 pm Post Subject:

It's just a picture I modified for the WIKI... should be 32A MCB, with 6mm² > junction box > 4mm² > sockets but I couldn't' be bothered re-drawing it.

securespark · Posted: Thu May 10, 2007 8:40 pm Post Subject:

I personally believe radials are far easier to extend, cannot be f*d about with & if 20A is not big enough, go large to 32A and up the cable to 6 milli...

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As George Michael once said, "..if you're gonna do it, do it right, right?"

Steve · Posted: Thu May 10, 2007 8:46 pm Post Subject:

4mm surely?