How would you do this?

[mbelectric]

Being relatively new, the biggest problem I have is lack of experience when it comes to deciding the easiest/quickest/cheapest/best way of doing an installation. I have been asked to install a new power circuit in a new kitchen extension. In the diagram below you can see the left wall, the facing wall and the right wall as you face it from the open plan entrance. There is a cu with a spare (RCD protected) way in the garage just behind the left hand wall. I was going to install a radial circuit protected by a 20a MCB.

The route I was intending to take is shown in red. The ceiling hasn't been plasterboarded yet so access via the ceiling void is easy. As a matter of interest how would anyone else so this?

Also, for the dishwasher, I was going to come down from the socket by the window and along the back of the units (in trunking). However, because of the window I cannot put an isolator above the appliance. Would it be ok for me to put an isolator to the right of the window (its about 2 metres away)?

Finally, it seems that some people suggest using a 20a DP switch as a means of isolating a socket whereas others say use a Switch Fused Spur. Is this just personal preference?

Untitled

• mbelectric
• 26 Oct 2008
• 2

 

[GaryMo]

Why a 20A radial and not a 32A RF? Would this provide power solely to the kitchen?

 

[mbelectric]

Yes, its purely for the kitchen. I thought a 20a radial would be ok for the number of sockets it was supplying. Would a 32a ring be more appropriate?

 

[Spark123]

A dishwasher can take the best part of 13A on its own - may not be a good idea to use a double socket for this. Might also be a good idea to have a switch for it.

 

[GaryMo]

Yes, I would say so due to the number of power hungry appliances located within a kitchen.

 

[RF Lighting]

Would a 32a ring be more appropriate?

Or a 4.0mm² radial if it's easier than running a RFC.

Will the socket for the extractor hood be accesible?

I personally like to see an isolator switch installed for that aswell. You could put it adjacent to the cooker switch maybe?

As for DP switches Vs FCUs, it is partly down to your own interpretation of BS7671 for wether it is acceptable or not.

I personally use DP switches as they are neater and you can install a grid switch with a few of them in. The ideal number of fuses per appliance is 1. If you use an FCU you will end up with two fuses unless you fit some sort of non standard outlet behind the appliance (such as a BS546 plug and socket)

If you do use 20A DP switches then you need to ensure that the switch can not possibly switch more than its rated 20A. This can be acheived by installing a SINGLE BS1362 socket, as the fuse in the plugtop will prevent more than 13A being drawn. If it were a twin socket, then you could draw 26A from this point wich would overload both the socket and the DP switch

 

[mbelectric]

The socket for the extractor would be between the top of the wall cabinet and the ceiling so is not readily accessible, so I will be installing an isolator for that reason.

I will also use a ring final as opposed to a radial.

I will use single sockets where a 20a DP switch is used as an isolator.

Many thanks for the help and advice. I obviously have a lot to learn.

 

[comms]

I tend to use a dual box located above the worktop for extractor isolator & a switch for pelmet lighting.
I also use 4mm radials in kitchens on 32a ocpd.

 

[GaryMo]

Is this a single or two storey extension?
Will there be any thermal insulation in the roof where you're going to run cables?

 

[mbelectric]

It was a downstairs bathroom which was adjacent to the original kitchen so I suppose its not an extension as such. He has knocked down the stud wall between the two and is going to use the old kitchen as a dining room. The ceiling void just has the joists with the odd cable and pipe running through them, there will be no insulation.

 

[ban-all-sheds]

What's the rating of the cooker?

Do any accessory makers do a grid system which includes a 32 or 45A switch?