Secondary Switchboard for kitchen from Primary Switchboard

[frarex]

I am currently working on my kitchen and I am centralising the switches for all appliances (Fridge, 2 Ovens, Induction Hob, Hood, Dishwasher, Washing Machine, boiler and counter sockets) on a secondary switchboard.

In order to do that I am running a 6mm multi-thread cable from the main switchboard (with a circuit breaker of 100Amp) to a secondary switchboard (with a circuit breaker of 40Amp).

The 6mm cables I am using are FG7(O)R that are supposed to carry around 50 Amp.

1) The person that recommended this setting says that the 6mm cable is absolutely fine to feed the secondary switchboard and that 40 amp are enough for a normal use of the appliances in the kitchen without the circuit breaker jumping.

2) Because I want to get the electrics certified I spoke with an electrician and he told me that the 6mm cable is not enough and 40 Amp for the kitchen might not be enough. He is reccomending a 25mm cables from the primary switchboard to the secondary switchboard with earth on a 10mm cable coming form the main earth.

I got two concerns:

1. I am a bit puzzled, before I changed the kitchen I had two 2.5 mm cables going into the kitchen that were running a similar number of appliances therefore I thought that a 6mm multi-thread cable was actually oversized to run the appliances.

2. Are the 40 amp of the secondary switchboard circuit breaker enough for a normal use of the appliances in the kitchen considering that the induction hob at full capacity uses 28 amp and that I might run washing machine (13 amp) dishwasher (13 amp) oven (15 amp) at the same time without considering boiler and fridge that might start at any time?

To be honest 25mm cables seem a bit too big to feed the secondary switchboard... but will a 6mm cable be enough? What if I start using the secondary switchboard and I realise I need a 60 amp breaker instead of the 40amp one?


Any suggestion about what I should do and who is right?

Thank you for your answers and apologies if similar question have been posted before, I tried to search the forum but I could not find anything relevant.

 

[Engineer54]

Why do you want or need a sub-distribution board in the kitchen in the first place?? Oh by the way, they are both Wrong, find a fully qualified electrician that actually knows what he's doing!!

 

[SirKit Breaker]

Hello mate,

I dont wish to pee on your bonfire, but, by the way you have worded your post, i know that you have neither the knowledge or experience to do this job. Your electrician has given you some good advice, my suggestion about what you should do, is get the electrician back, and ask him to do the job for you, before you make a pigs ear of it, and either kill or injure yourself or someone else, or burn the place down. This electric lark is not rocket science, but it has to be done properly.

Cheers............Howard

 

[frarex]

Why do you want or need a sub-distribution board in the kitchen in the first place?? Oh by the way, they are both Wrong, find a fully qualified electrician that actually knows what he's doing!!

Because I think it is tidier to have all switches in one place and also I am having a glass splashback and it would not look as nice with holes for the switches for the various appliances.

BTW I am not that experienced with electrics however I can use common sense and I am doing some research to improve my knowledge although still poor.

Any further comments are therefore welcome.

 

[Adam W]

You could have a bank of grid switches, which could look better and be more accessible than having a separate consumer unit in your kitchen.

 

[guest119]

I smell a wind up.

Boydy

 

[Engineer54]

Because I think it is tidier to have all switches in one place and also I am having a glass splashback and it would not look as nice with holes for the switches for the various appliances.

BTW I am not that experienced with electrics however I can use common sense and I am doing some research to improve my knowledge although still poor.

Any further comments are therefore welcome.

So for what purpose do you need a separate CU in the kitchen, surely not to use the MCB's as switches??

Ahhhh!! You mean your more interested in what the kitchen looks like, than it actually functioning as a kitchen!! I take it, you don't want to see any socket outlets above the worktop for general kitchen appliances either?(kettle/toaster/coffee machine etc)!! Don't tell me, they will all be fitted in the cabinets. lol!!

Think you've been watching too many TV hairy fairy designer home improvement programmes. Where they seem to forget that kitchens are WORK areas, not a TV show area!!

 

[Knobhead]

Aesthetics and incompetence V’s practicality. Hands down winner for the former.

Get a qualified electrician before you make some expensive impractical mistakes!

 

[chrish_1977]

Why do you want or need a sub-distribution board in the kitchen in the first place?? Oh by the way, they are both Wrong, find a fully qualified electrician that actually knows what he's doing!!

Because I think it is tidier to have all switches in one place and also I am having a glass splashback and it would not look as nice with holes for the switches for the various appliances.

BTW I am not that experienced with electrics however I can use common sense and I am doing some research to improve my knowledge although still poor.

Any further comments are therefore welcome.

If you aren't experienced, then I would suggest you get someone in who is, not something you can just google the answer for, there are many variables from what size cable to installation method to breaker sizes etc all need to be worked out and not guessed because you don't think it's necessary

 

[frarex]

So for what purpose do you need a separate CU in the kitchen, surely not to use the MCB's as switches??

Ahhhh!! You mean your more interested in what the kitchen looks like, than it actually functioning as a kitchen!! I take it, you don't want to see any socket outlets above the worktop for general kitchen appliances either?(kettle/toaster/coffee machine etc)!! Don't tell me, they will all be fitted in the cabinets. lol!!

Think you've been watching too many TV hairy fairy designer home improvement programmes. Where they seem to forget that kitchens are WORK areas, not a TV show area!!

I believed it was a better solution, neater because all switches are in one place and I can house the CU inside a cabinet.

The motivation was both functional and aesthetic as the kitchen is open plan.

In the continent people do not put switches and fuses for each appliance as well as they do not do rings. The circuit is radial running a cable from the main switchboard to the appliance or socket.

I was reading somewhere that the practice to do rings is typical of the uk and that radial circuits are safer.

Re. plugs... you are close, lol, I found some plugs that get mounted underneath the wall cabinets and one of them will be mounted on the worktop.

I am trying to do something safe, practical and aesthetic.

THANK YOU FOR ALL YOUR COMMENTS AND RECOMMENDATIONS. Please keep them coming, I need to find a suitable solution.

So far I understand that general consensus is:

6mm cable from main CU is too small
25mm cable from main CU is too big

A 10mm cable should be enough to feed the secondary CU

40 Amp Circuit breaker on the secondary CU should suffice for a normal use of the appliances in the kitchen


PS No, no do not watch TV... I am originally Italian though and we probably got a chip to make things look nice.

 

[Octopus]

I believed it was a better solution, neater because all switches are in one place and I can house the CU inside a cabinet.

The motivation was both functional and aesthetic as the kitchen is open plan.

In the continent people do not put switches and fuses for each appliance as well as they do not do rings. The circuit is radial running a cable from the main switchboard to the appliance or socket.

I was reading somewhere that the practice to do rings is typical of the uk and that radial circuits are safer.

Re. plugs... you are close, lol, I found some plugs that get mounted underneath the wall cabinets and one of them will be mounted on the worktop.

I am trying to do something safe, practical and aesthetic.

THANK YOU FOR ALL YOUR COMMENTS AND RECOMMENDATIONS. Please keep them coming, I need to find a suitable solution.

So far I understand that general consensus is:

6mm cable from main CU is too small
25mm cable from main CU is too big

A 10mm cable should be enough to feed the secondary CU

40 Amp Circuit breaker on the secondary CU should suffice for a normal use of the appliances in the kitchen


PS No, no do not watch TV... I am originally Italian though and we probably got a chip to make things look nice.

You need to find a competent Electrician matey.,

 

[Engineer54]

I believed it was a better solution, neater because all switches are in one place and I can house the CU inside a cabinet.

Though this is a fairly common practice for commercial establishments, it's not a by any means a good practice especially for domestic installations, and the idea should be forgotten...

The motivation was both functional and aesthetic as the kitchen is open plan.

In the continent people do not put switches and fuses for each appliance as well as they do not do rings. The circuit is radial running a cable from the main switchboard to the appliance or socket.

Forget the continent, you are working to BS7671 in the UK. Rings and radials both have their place in kitchen installations and both are completely safe when installed correctly by competent electricians. You'll find that most socket MCB's on the continent are also Double Pole, which they are not in the UK. Don't try and emulate another countries standards, when you don't fully understand them.

I was reading somewhere that the practice to do rings is typical of the uk and that radial circuits are safer.

Then you have been reading rubbish!! lol!!

Re. plugs... you are close, lol, I found some plugs that get mounted underneath the wall cabinets and one of them will be mounted on the worktop.

Well i'm glad to hear that your not hiding sockets for small appliances in the cabinets, that would be waiting for an accident to happen!!

I am trying to do something safe, practical and aesthetic.

THANK YOU FOR ALL YOUR COMMENTS AND RECOMMENDATIONS. Please keep them coming, I need to find a suitable solution.

So far I understand that general consensus is:

6mm cable from main CU is too small
25mm cable from main CU is too big

A 10mm cable should be enough to feed the secondary CU

40 Amp Circuit breaker on the secondary CU should suffice for a normal use of the appliances in the kitchen


PS No, no do not watch TV... I am originally Italian though and we probably got a chip to make things look nice.

Again, as others have told you, get your actual installation advice from a qualified, competent and experienced electrician. And for gods sake forget about using MCB's as your appliance switches, their are other methods to achieve what your wanting to do!!

 

[telectrix]

when you say "underneath the wall cupboards", i sincerely hope you mean on the wall and not fixed to the cupboards themselves!.

 

[keniff]

I would take all feeds from your original fuseboard to a grid switch in the kitchen, scrap the local fuseboard and click do I nice range of modules to mix and match and if your not sure get someone in it will cost alot more if you undersize or miss a cable out!!

 

[ian.settle1]

Lads give up



He can't hear you nothing in between

 

[guest119]

Yes Ian, Keniff was starting to give advice and I was tempted to comment like you did.
There are times to advise and times advisable not to.

Boydy

 

[Engineer54]

when you say "underneath the wall cupboards", i sincerely hope you mean on the wall and not fixed to the cupboards themselves!.

I ''think'' he means something along the lines of one of these.... Fixing to wall and wall cabinet. He would better off using the trunking rather than the individual modules. He can then mount and change position of outlets as and where required. My even be able to fit his grid type switches using one of these systems too...

Marshall Tufflex> Home > Cable Management > Domestic / Commercial Trunking > Bench Trunking

Marshall Tufflex> Home > Cable Management > Domestic / Commercial Trunking > Bench Trunking

Not sure if he is thinking along the lines of the ''pop-up'' worktop fitted socket outlets?? I hope not, they are basically just a fancy extension lead affair

 

[chrish_1977]

Sounds more like he wants to do it his way and stuff the regs

 

[Adam W]

Sounds more like he wants to do it his way and stuff the regs

LOL it sounds like one of those threads which goes:
"can I do this?"
"not really, no - there are much better ways of doing it"
"yes but can I do this?"
"it's really not a good idea"
"but do the regs expressly forbid it?"
"the regs don't work like that"
"so there's nothing which says I can't do it?"
"sigh."

Apparently in Italy you can't use several appliances at the same time without it all tripping out. They just seem to accept it as a fact of life.

 

[Octopus]

Sounds more like he wants to do it his way and stuff the regs

Probably doesn't even know regs apply!

 

[Redvanman]

I ''think'' he means something along the lines of one of these.... Fixing to wall and wall cabinet. He would better off using the trunking rather than the individual modules. He can then mount and change position of outlets as and where required. My even be able to fit his grid type switches using one of these systems too...

Marshall Tufflex> Home > Cable Management > Domestic / Commercial Trunking > Bench Trunking

Marshall Tufflex> Home > Cable Management > Domestic / Commercial Trunking > Bench Trunking

Not sure if he is thinking along the lines of the ''pop-up'' worktop fitted socket outlets?? I hope not, they are basically just a fancy extension lead affair

Engineer I reckon he means these

Under Cabinet Sockets in DIY Electrical Fittings | eBay

 

[Engineer54]

Engineer I reckon he means these

Under Cabinet Sockets in DIY Electrical Fittings | eBay

Which is basically what i said he means, regardless of what manufacturer he chooses. I must say, those eBay units look like really cheap and nasty outlets.

 

[bartkusal]

I am currently working on my kitchen and I am centralising the switches for all appliances (Fridge, 2 Ovens, Induction Hob, Hood, Dishwasher, Washing Machine, boiler and counter sockets) on a secondary switchboard.

In order to do that I am running a 6mm multi-thread cable from the main switchboard (with a circuit breaker of 100Amp) to a secondary switchboard (with a circuit breaker of 40Amp).

The 6mm cables I am using are FG7(O)R that are supposed to carry around 50 Amp.

1) The person that recommended this setting says that the 6mm cable is absolutely fine to feed the secondary switchboard and that 40 amp are enough for a normal use of the appliances in the kitchen without the circuit breaker jumping.

2) Because I want to get the electrics certified I spoke with an electrician and he told me that the 6mm cable is not enough and 40 Amp for the kitchen might not be enough. He is reccomending a 25mm cables from the primary switchboard to the secondary switchboard with earth on a 10mm cable coming form the main earth.

I got two concerns:

1. I am a bit puzzled, before I changed the kitchen I had two 2.5 mm cables going into the kitchen that were running a similar number of appliances therefore I thought that a 6mm multi-thread cable was actually oversized to run the appliances.

2. Are the 40 amp of the secondary switchboard circuit breaker enough for a normal use of the appliances in the kitchen considering that the induction hob at full capacity uses 28 amp and that I might run washing machine (13 amp) dishwasher (13 amp) oven (15 amp) at the same time without considering boiler and fridge that might start at any time?

To be honest 25mm cables seem a bit too big to feed the secondary switchboard... but will a 6mm cable be enough? What if I start using the secondary switchboard and I realise I need a 60 amp breaker instead of the 40amp one?


Any suggestion about what I should do and who is right?

Thank you for your answers and apologies if similar question have been posted before, I tried to search the forum but I could not find anything relevant.

And we all missed the obvious. The OP is planning to protect the 50A cable, with a 100A MCB.

 

[frarex]

Thanks again for your replies.

I am now looking for an electrician to make sure that everything is ok...

In the meantime I run a 10mm2 (64A) cable from the main CU, to the secondary CU, I will probably start using it with the 40A breaker and if it jumps too easily I will change it with a 63A breaker.

FYI The under cabinet sockets I got are:

Double socket | Häfele UK Ltd

Other issue is:
- the person that designed the kitchen cabling did the sockets as "radial" (i.e. one cable to the CU for each plug) rather than "ring". We meant to use a box (which is difficult to find) to connect (with a 6mm cable) the 7 sockets to a 32A switch. The first electrician that came around to have a look said that that radial is not possible in the UK because ring is the standard and if I want do do it radial I need a switch in the CU for each plug. Is this correct?

Radial systems should be more secure, because if the ring breaks the a 2.5 mm cable might overheat... somewhere I read that that is one reason why fires because of electric faults are more common in the UK than in other countries.

The Uk is the only country where "rings" are used.

 

[guest119]

Yep,I always thought this was a wind up.

Boydy

 

[Engineer54]

Your just not going to listen to any sense that you are being given are you ?? Your still going to be a complete bloody idiot by using MCB's as socket outlet switches, when there is no need whatsoever. Not only that, your going to mount a CU in a kitchen cabinet!! lol!!

Oh, and those kitchen fitting shop under cabinet outlets you posted up, well they are going to last about 5 minutes!! They even have a 10A restriction rating on them before you start!! lol!! Are you sure these are not fixed extension leads, because they very much look like it to me!!!

Complete waste of anybodies time and effort advising anything to you, because you seem to know far better than everyone here!! Good luck to you on your project, i'm thinking your going to need it, if not now then later, when this can of worms is finished!!

somewhere I read that that is one reason why fires because of electric faults are more common in the UK than in other countries.

You really do read some crap don't you. You must believe everthing you read, try looking at domestic electrical fires in the States!! lol!!

 

[Outspoken]

Thanks again for your replies.

I am now looking for an electrician to make sure that everything is ok...

In the meantime I run a 10mm2 (64A) cable from the main CU, to the secondary CU, I will probably start using it with the 40A breaker and if it jumps too easily I will change it with a 63A breaker.

FYI The under cabinet sockets I got are:

Double socket | Häfele UK Ltd

Other issue is:
- the person that designed the kitchen cabling did the sockets as "radial" (i.e. one cable to the CU for each plug) rather than "ring". We meant to use a box (which is difficult to find) to connect (with a 6mm cable) the 7 sockets to a 32A switch. The first electrician that came around to have a look said that that radial is not possible in the UK because ring is the standard and if I want do do it radial I need a switch in the CU for each plug. Is this correct?

Radial systems should be more secure, because if the ring breaks the a 2.5 mm cable might overheat... somewhere I read that that is one reason why fires because of electric faults are more common in the UK than in other countries.

The Uk is the only country where "rings" are used.

What utter drivel. Sorry, but you're not listening to advice given and what you are proposing is a total nonsense. There are far simpler ways to achieve your ends and doing it safely and in a compliant way.

You have NO understanding of electricity and no understanding of what you actually want to do, stick to your day Job and lets the professionals do theirs, in the long run you will save money by shutting up and allowing an electrician to solve the problem for you...all you need to do is tell him/her what you want and allow them to decide the most practical path.

Dump the idea of a sub-main to a separate board, it is a total nonsense in a domestic setting and does nothing to solve your problem, you have no more thought this out than Nick Clegg thinks before speaking!

 

[telectrix]

love the nick clegg reference.

and sounds like the OP is going to use frogs for OCPDs.

 

[Silvermerlin]

Get a qualified electrician in to do the job, It will be done right and correctly tested and certified

 

[Brightspark2]

Which is basically what i said he means, regardless of what manufacturer he chooses. I must say, those eBay units look like really cheap and nasty outlets.

Probably made in china........

 

[Outspoken]

Probably made in china........

I think one of these is called for here

 

[Rampantchilli]

Radials are safe and have thier place in the uk.
rings are also safe and also have thier place in the uk.

the idea of running a sub main to a second CU in domestic setting is admirable but over complicating a simple job, you should not use circuit breakers as switching for your appliances, firstly they are not intended to be used for regular on off actions, this could cause wear and ultimately failure.

the 10mm cable can carry 64a, BUT that's makes 2 assumptions,
first
its flat twin and earth
second
its clipped directly to the wall, without being enclosed or covered with insulation.

so with those 2 assumptions satisfied yeah you could potentially upgrade to a 63a mcb/Rcd combination, but they are not likely to be satisfied, as you don't want anything on show, so worst case scenario is the cable can only carry 32a.

when you had an electrician on site and he advised you, he is the best person to listen to, for all the advice we have given has been given on the information YOU have supplied, but with your limited( and that's being kind) knowledge of bs 7671, you may have left out some very valuable information, like the construction of the building, or that your 17th century mansion has its own power station which runs on 110v.

get an electrician in, tell him what you want including some central controls, then let HIM tell YOU the best way of doing it, not the other way round. Laws and regulations need to be satisfied before any consideration of your aesthetic opinion.

 

[telectrix]

but don't get the spark who advised that you need a separate MCB for each socket outlet. he's got less knowledge of electrics than i have of piloting a helicopter.

 

[Outspoken]

but don't get the spark who advised that you need a separate MCB for each socket outlet. he's got less knowledge of electrics than i have of piloting a helicopter.

I'd pay to see you try though

 

[telectrix]

haha. i can fly a fixed wing tin can, but not an egg-beater.

 

[Engineer54]

the idea of running a sub main to a second CU in domestic setting is admirable but over complicating a simple job, you should not use circuit breakers as switching for your appliances, firstly they are not intended to be used for regular on off actions, this could cause wear and ultimately failure.

There's nothing admirable about running a sub-main to a separate CU, for a typical run of the mill domestic kitchen!! If the house was the size of a mansion, that would may be another matter!!

This guy is a total idiot, and isn't going to listen to anyone. Best leave him to his own devices!!

 

[heartofgold]

Smells like he'll be needing a qualified spark to save him a load of cash by doing it properly and certifying it on completion. !!