Sockets Ring Wiring

[peterniss]

We are looking at rewiring kitchen/diner. This is served by a single ring main from 32A MCB, but looking to replace all the existing sockets with new ones in new places.

I have two questions. First, I know it is required to use harmonized colour cable for new wiring, but would it be acceptable to leave in place the existing cable from the CU to each end of the ring, and then use new colour cable for all the new wiring. This would mean the first and last socket would have one connection with old black red colour cable and one with the new brown blue colours.

Second, what is the limit on number of sockets in a ring? The plan is for 14 sockets plus connections to dishwasher, extractor hood and gas hob ignition.

Many thanks for any answers.

Peter

 

[mikethesparky]

Hi Peter, firstly you do understand that under Part P regulations the work you are about to undertake will all be notifiable as it is a new circuit. as for the mixing of colours, you really should replace the legs down to the CU, as this will be a new ring, by leaving in the old legs you will have mixed colours in the same ring, leaving old circuits in and having new ones alongside is ok but not having mixed wiring in the same ckt.

as for your final question, it doesn't really matter how many sockets and spurs you have on the ring as long as the load your putting on them does not exceed the ckt capacity, lots of sockets for convienience is ok just don't go whacking high current appliances in every outlet at once. lol

hope that helps.

 

[Taylortwocities]

I'm gonna disagree, to some extent.

It is perfectly acceptable to leave the existing two ends in black/red and then continue the ring in blue brown cable. You must post the approved warning sign at the consumer unit re mixed colours.
Oh yes, and the old cable must be capable for the load.

This is then not a new circuit but an alterattion to an existing one.

This work is still notifiable as it is being carried out in a special location (kitchen).

 

[ericmark]

I agree with Taylortwocities.
Eric

 

[securespark]

As per TTC's comment about making sure the cable is suited to the load, is the cpc csa 1mm or 1.5 mm sq?

If 1mm, then the protection of choice should really be a type B breaker.

 

[aptsys]

There is also no harm in sleeving the red and black conductors brown and blue to avoid confusion.

 

[peterniss]

What a great forum! Thanks to all for these answers, which are all clear and to the point.

The cable is 2.5 mm sq, and there is already a type B 32 A MCB in place.

It will be much easier to leave the existing ends to the CU in place as they run 7-8 metres down a landing and the CU is just below ceiling height and the floor above is a bathroom which has a tiled floor, so access is tight at best.

I was thinking of DIY and doing a notification to LABC but have managed to engage a proper Spark to do this now.

Thanks again.

Peter

 

[ban-all-sheds]

There is also no harm in sleeving the red and black conductors brown and blue to avoid confusion.

A much better way to avoid confusion is to use red & black cable for the new wiring, if you can get it or have some.

 

[Lectrician]

The cable is 2.5 mm sq, and there is already a type B 32 A MCB in place.

Yup, but the CPC will be slightly smaller. If it is 1.5, no worries. If it is 1.0mm, then extra considerations need to be made as stated above.

A spark can eye a cable quickly for size, but it is difficult to tell via a photo, or give tips on how to determine the size.

 

[ban-all-sheds]

One of these is accurate enough to measure conductor diameters:

Alternatively get a length of 1.5mm² T/E, as that will have 1.5mm² and 1.0mm² conductors in it for comparison. There's ony 0.25mm difference in the diameter though, so look closely....

 

[peterniss]

I would prefer to do as Ban-all-sheds suggests and use black/red cable. Why on earth did they change the colours anyway? And I have an almost full reel of black and red 2.5mm sq.

But I understood new wiring had to be with the new colours to meet regs requirements??

Peter

 

[ban-all-sheds]

I would prefer to do as Ban-all-sheds suggests and use black/red cable. Why on earth did they change the colours anyway?

http://www.theiet.org/publishing/wiring-regulations/colour/

And I have an almost full reel of black and red 2.5mm sq.

Then use it.

But I understood new wiring had to be with the new colours to meet regs requirements??

Well, firstly, you don't actually have to comply with the wiring regulations, even though it's a BGI.

Secondly, you can comply with them in all respects except cable colour and list it as a departure on your certificate.

 

[peterniss]

Many thanks for that B-A-S.

Is there a document on the process for listing departures that you could reference for me? I ask in case the Spark I am using is not comfortable with this, since he will have to issue my certificate.

Regards

Peter

 

[ban-all-sheds]

Regulation 120.3 applies in this case, and where he signs the EIC to say:

I being the person responsible for the Design, Construction, Inspection & Testing of the electrical installation (as indicated by my
signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design,
Construction, Inspection & Testing, hereby CERTIFY that the said work for which I have been responsible is to the best of my
knowledge and belief in accordance with BS 7671:2008 amended to .......... (date) except for the departures, if any, detailed as follows:

below that is a box to list departures.

But if you get a hard-of-thinking electrician he might insist that he's "not allowed" to use the old colours.

 

[peterniss]

"Hard-of-Thinking" -- I love the euphemism!

Thanks very much for this. I'll see what he says, would be a great shame to waste this perfectly good cable and end up with a mix of old and new colours.

Regards

Peter