Circuits for white goods

[DJ12345]

Hello everybody! I just wanted to ask, what would be the best practise to run circuits for white goods?
In my plan what i see is:
1. Fridge & Freezer 20 amp RCBO radial wired with 2.5mm
2.Washing machine 20 amp MCB Radial 2.5mm
3. dish washer 20 amp mcb radial with 2.5mm
4. Washing machine and dish washer 32 amp mcb wired 2.5mm ring final.

Please advice what is the best practise to do it? would it be too much having dish washer and washing machine on separate circuits or just wire them both on ring final?

Also advice me please with mcb sizes if i am correct about radials. As far as i rememmber from regs maximum mcb rating for radial is 16amp.

Thank you

 

[DPG]

Why RCBO for the fridge and MCBs for the rest?

 

[DJ12345]

Why RCBO for the fridge and MCBs for the rest?

I have seen it before, worked in few houses like that, thats why i am asking whats is the best practise.

 

[DPG]

I have seen it before, worked in few houses like that, thats why i am asking whats is the best practise.

Surely you will need RCD protection?

 

[DJ12345]

Surely you will need RCD protection?

CU has 2 Rcd in it.

 

[DJ12345]

Consumer Unit has 2 RCD protected sections.

 

[nicebutdim]

Consumer Unit has 2 RCD protected sections.

RCBO for fridge freezer protected by RCD?

 

[DPG]

Consumer Unit has 2 RCD protected sections.

So why the RCBO for the fridge? Can you give use a bit more info, it feels like a bit of a drip feed.

 

[stevethesparks]

Is the CU a high integrity unit?

 

[brianmoooore]

If this is a domestic set up, a single 2.5mm2 radial fed by a 20A RCBO is adequate for all three, if the water heating elements in the dishwasher and washing machine are 2kW.
If either are 3kW, then a 4mm2 radial fed by a 32A RCBO will do, but the washmac. and dishwasher shouldn't both be plugged into the same double 13A s/socket.

 

[DJ12345]

If this is a domestic set up

Yes it is.

and dishwasher shouldn't both be plugged into the same double 13A s/socket.

Unswitched socket behind devices on the wall and fused switched spur on the wall above worktop.

 

[DJ12345]

So why the RCBO for the fridge?

If device fails it trip only one protected circuit, not all circuit will be off in RCD unit

 

[DJ12345]

RCBO for fridge freezer protected by RCD?

no

 

[telectrix]

RCBO for freezer, rest in a 32A RFC with 20A D/P switches above w/top feeding single sockets below. unless you want a load of grief fitting grid switches.

 

[DJ12345]

unless you want a load of grief fitting grid switches.

I just thought about grid switches. Just have 4 circuits(dish washer, washing machine, hood, freezer).

 

[DPG]

If device fails it trip only one protected circuit, not all circuit will be off in RCD unit

So is this a high integrity unit then?

 

[DJ12345]

So is this a high integrity unit then?

Yes

 

[telectrix]

Yes

BG?

 

[DJ12345]

BG?

SE

 

[DPG]

Has this forum started charging by the word or something?

 

[telectrix]

FK

 

[pc1966]

Also advice me please with mcb sizes if i am correct about radials. As far as i rememmber from regs maximum mcb rating for radial is 16amp.

The only maximum rating for a MCB is either the:

• cable overload limit
• fault clearing Zs value, or
• whatever a specific load requires.

There is no "radial" limit as such. With 13A sockets you already have a load-limiting fuse in the plug so it comes down to adequate cable protection.

Personally I would just put the lot on a 32A RCBO for a ring final circut as at least if it trips you have more feedback it has gone, rather than waiting until some time later to find the fridge has been off for ages and nothing else is showing a fault. Or get a fridge alarm!

But as mentioned above make sure all of the feed points have accessible means of isolation. So ideally double-pole switches feeding an un-switched socket if it has to be behind the appliance. You don't need DP for powering it down safely, but you do if you want to prevent a N-E fault causing RCD troubles.

 

[DJ12345]

Thank you for your replies guys, my last question would be how does kitchen grid nswitches are wired? does they have to be on the ring? and linked between each other? or i can wire them on radial? dedicated load to each switch?for example dedicated load from CU to fridge freezer switch,then dedicated load to washing machine switch, and etc?

 

[pc1966]

Grid switches are just modules that clip in to a support template, and then fit behind the faceplate. They are not wired internally, you have to do that.

Advantage is the look neat and you can mix and match them.

Disadvantages are they are tight in there (you need a deep back-box and care to wire up) and some folk have had issues of them burning out more than the full-size 20A switches do.

Typically they will take a single 4mm cable, or 2*2.5mm, but that is about it. So on a typical RFC you can link the supplies to each switch in the loop. But again needs a bit of care.

 

[pc1966]

If you were doing a grid-switch for the lot you might as well run it as a 4mm radial on 32A and then put some 5-way wago joints in the back of the box to fan it out on 2.5 to each switch.

It might be the switchs take 2*4mm but I would try it out before committing.

 

[DJ12345]

So on a typical RFC you can link the supplies to each switch in the loop. But again needs a bit of care.

Can you connect each switch to radial? i mean run dedicated supply to each switch?

 

[pc1966]

You can use them as any normal switch, so if you want each on a radial feel free to do so.

 

[pc1966]

Just corrected an earlier post to say I would use an un-switched socket with a separate switch. No real need for two switches and it is just another thing to forget to put "on" before pushing a washing machine back, etc.

 

[DJ12345]

You can use them as any normal switch, so if you want each on a radial feel free to do so.

Thank you! So if i run 2.5mm radial from rcbo 20A to one switch,labeled as washing machine then run another 2.5mm radial from another RCBO 20a to another switch labelled dish washer. WIll that be good practice?

 

[pc1966]

Thank you! So if i run 2.5mm radial from rcbo 20A to one switch,labeled as washing machine then run another 2.5mm radial from another RCBO 20a to another switch labelled dish washer. WIll that be good practice?

Yes, that is perfectly good practice.

The RFC versus a few radials argument with run and run, but what matter is each circuit is safe & adequate for the load(s) and correctly labelled.

 

[ipf]

I seems a lot of circuits for a kitchen. What about general sockets for kettle, toaster, etc?
In general, diversity has a big say in final loading, taking into consideration what's going to be used regularly at the same time.
Unless it's an outsize kitchen, one RFC and, maybe the odd radial, would be my option.
How big is the house and how big a CU do you want?

 

[DJ12345]

I seems a lot of circuits for a kitchen. What about general sockets for kettle, toaster, etc?

Sockets are separate ring.

In my opinion is always better to have load balanced.Correct me if i am wrong.

 

[ipf]

What do you mean by 'load balanced'? Presumably it's a single phase supply.

 

[DJ12345]

What do you mean by 'load balanced'? Presumably it's a single phase supply.

I mean separate, sorry my bad.

 

[Mike Johnson]

I tried the grid switch route with neons to indicate they were on, the switch's where engraved with the function of each circuit, but in the end it became too busy inside the 35mm back box and I resorted to radial circuits for each appliance, this was in France where radials are the norm, in the UK I run all of the white goods off an RFC, sockets in the back of a tray space so no need for switches above the worktop.

But if you must:

20 Amp DP Grid Switch - Washing Machine

 

[goasis]

Do you want a local electrician to price this work for you? Someone on the forum may be local

 

[DPG]

Do you want a local electrician to price this work for you? Someone on the forum may be local

I think this is a good plan. And you will get the necessary certification for the job.

 

[Pete999]

Where is he based?

 

[DPG]

Where is he based?

London

 

[Pete999]

London

Thanks