Extension Wiring

[bandit1200]

I am about to wire my new extension, and would appreciate guidance on a couple of things I am getting hung up on. I would like to do the following setup, but am unsure if the 32a ring main is enough if there is going to be the washer/dishwasher/tumble drier on it 9kw = 35A or is this not bothered about?

1 radial to 2 bedrooms, 4 double sockets on 20a breaker via 2.5mm te
1 radial to fridge socket in new kitchen and freezer socket in old pantry on 16a breaker via 1.5mm te
1 ring rcd protected through garage socket all kitchen sockets and double in conservatory on 32a breaker via 2.5mm te
1 radial lighting circuit 2 bedrooms kitchen and garage on 6a breaker via 1.5mm te
1 radial to cooker (which will be gas anyway) on 40a breaker via 6mm te

I was going to wire the garage, bedrooms, kitchen and conservatory on 1 ring with rcd and another for the washing/tumble/dishw without rcd, but am trying to reduce the traffic at the consumer unit, hence the radial suggested for the bedrooms - can this be 1.5mm?.

Another question - I am coming out of the cu directly into the garage. Does it matter how tight the cables are together through the conduit between the garage and cu, and are they okay clipped to the wall within 150mm of the ceiling until they enter the kitchen or do they have to be in trunking?

 

[Adam_151]

Here is what I'd do

1 radial to 2 bedrooms, 4 double sockets on 20a breaker via 2.5mm te

(or a 32A ring, but realistically you don't need it)

1 radial to fridge socket in new kitchen and freezer socket in old pantry on 16a breaker via 1.5mm te

2.5mm² for this

1 ring rcd protected through garage socket all kitchen sockets and double in conservatory on 32a breaker via 2.5mm te

Kitchen on its own ring (or 4mm² radial), you might want to have a submain for the garage, or you could just put a ring in there, might be be worth having a separate radial for conservatory, but relistically probably not needed

1 radial lighting circuit 2 bedrooms kitchen and garage on 6a breaker via 1.5mm te

Nothing wrong with this, but if you do have a submain in the garage (as per my above point) then garage would want a separate circuit from this board

1 radial to cooker (which will be gas anyway) on 40a breaker via 6mm te

10mm²

I'd also fit a 32A dedicated 4mm² radial for the tumble/wash/dish

 

[securespark]

Better off with 20A breaker for a radial with more than one outlet?

 

[Adam_151]

Better off with 20A breaker for a radial with more than one outlet?

eh ??

Think one of us might have got confussed somewhere

 

[ban-all-sheds]

am unsure if the 32a ring main is enough if there is going to be the washer/dishwasher/tumble drier on it 9kw = 35A or is this not bothered about?

http://www.iee.org/Publish/WireRegs/Amd1andRC.pdf

Personally, for appliances I like the idea of a 4mm² radial to a grid plate with DP switches and fuse modules supplying 15A sockets via 1.5mm²..

I was going to wire the garage, bedrooms, kitchen and conservatory on 1 ring with rcd and another for the washing/tumble/dishw without rcd, but am trying to reduce the traffic at the consumer unit, hence the radial suggested for the bedrooms - can this be 1.5mm?.

Not sure what you mean about reducing the traffic by use of a radial....

 

[bandit1200]

but am trying to reduce the traffic at the consumer unit, hence the radial suggested for the bedrooms"

I meant that I was going to come out of the cu with 1 2.5mm cable then loop it through 4 double sockets in the bedrooms rather than have a ring with two cables at the cu. Is this a no no?

"Another question - I am coming out of the cu directly into the garage. Does it matter how tight the cables are together through the conduit between the garage and cu, and are they okay clipped to the wall within 150mm of the ceiling until they enter the kitchen or do they have to be in trunking?"

Any answers to this?

Thanks.

 

[ban-all-sheds]

I meant that I was going to come out of the cu with 1 2.5mm cable then loop it through 4 double sockets in the bedrooms rather than have a ring with two cables at the cu. Is this a no no?

It's not a no-no, and in many ways radials are better than ring finals, but I just wondered why you feel you want to reduce the number of cables at the CU

"Another question - I am coming out of the cu directly into the garage. Does it matter how tight the cables are together through the conduit between the garage and cu,

Might do - how long is the run where they are in conduit? How many/what size cables, and what size conduit?

and are they okay clipped to the wall within 150mm of the ceiling until they enter the kitchen or do they have to be in trunking?"

If they are clipped to the wall, i.e. visible, then they can be wherever you like, subject to risk of damage etc.

 

[bandit1200]

Thanks Ban. The only reason that I want to reduce the wires to the unit is that I have one incoming slot left at the back of the cu which is about 2" * 1". I have drilled through the wall 2 * 22mm holes behind this slot to insert 20mm conduit. This is the conduit through which I asked how tight the wires can be. They are wall depth i.e 275mm. Should I be aiming to drill a single larger hole, or should all the wires pass through?

Thanks.