Kitchen Wiring

[Lankydan]

Hey guys, first time ever posting on a forum. Wanted some clarification on the below design I've found or any improvements that could make it better. Does it comply with the regs? Will it work? Is it safe?

Kitchen Wiring

• Lankydan
• 23 Apr 2020

General idea is to use a grid panel to house DP switches instead of several appliance switches above the worktops. And for the dishwasher and washing machine to be incorporated into the ring main double socket circuit as radials.

The oven, microwave, dishwasher and washing machine are all integrated. I'd read that any supply to a item with gas must have a 3A FCU as protection (gas boiler, gas hob etc.).

Thanks in advance with all your time and help.

 

[EFLImpudence]

Assuming no cable has to be derated for installation methods such as running in conduit or thermal insulation.



Left side - 4mm² is adequate and satisfactory for a 32A radial.

Centre - There is no point having a ring if one side is merely the return leg to the MCB.

Right - You do not need a 3A FCU for the igniter but, obviously you will need some sort of connector.
Hardly worth having a separate circuit for igniter and hood. I would connect to the oven circuit/switch



Switches above the worktop are not a requirement, merely personal choice,

 

[flameport]

Does it comply with the regs? Will it work? Is it safe?

It might comply, although much of whether it complies is down to how it's installed. It would probably work, although it's a contrived mess.
3A is the standard value for hob ignition and boilers. It's not 3A just because it's a gas appliance.

Do you actually want a panel of grid switches in your kitchen? They are neither required or useful.

As for the diagram:
4 double sockets in a kitchen is woefully inadequate.
Completely unnecessary to have that separate 6A circuit just for an extractor and hob ignitor - those could just as easily be supplied from the 32A ring.
A ring may not be the best design, and it certainly isn't compulsory.

32A circuits do not need to be installed in 6mm² cable, and 6mm² won't actually fit into most grid switches.
There is also the question of how the wiring to the 2 grid switches is actually implemented in reality - drawn as 2 lines that join on the diagram, but in practice it can't be done like that.

 

[ericmark]

You need a 20A MCB to feed 20A isolators or go for a cooker switch. The ring final is OK with 20A isolator as it feeds a socket so there is a 13A fuse, the appendix says fixed items over 2 kW should have a dedicated supply, in real terms if the washer/drier or drier is reasonable central on the ring final there is no problem, but could cause over load if at either end.

However any new circuits need notifying, and also must be RCD protected, some one needs to sign the installation certificate to say they have 1) Designed the circuit, 2) Installed the circuit, 3) Inspected and tested the circuit. If you need to ask the question you clearly have not got the skill to design the circuit.

If in Wales the whole lot is notifiable even if not a new circuit, in real terms in Wales it is cheaper to get an electrician to do the work than pay the LABC fees.

OK you may want to break the law, that is up to you, however it would be wrong not to tell you that is would be breaking the law, personally I don't care, but you need to realise there may be a problem if you try to sell the house. I know it is really a tax, and the LABC don't really do anything, but now is the time to make you aware, not when you try and sell the house.

 

[Lankydan]

Thanks for your advice. Will take it on board.

There is no point having a ring if one side is merely the return leg to the MCB

Isn't that the definition of a ring main circuit? All ring main circuits have 2 legs to the circuit. The distance from the MCB to the double socket on either side is approx. the same distance.

4 double sockets in a kitchen is woefully inadequate.

How is 4 double sockets inadequate? That's 5 plug sockets that are free around the room. It's a fairly small kitchen as well.

 

[EFLImpudence]

Isn't that the definition of a ring main circuit?

Yes, they are ring final circuits; not ring mains.

All ring main circuits have 2 legs to the circuit. The distance from the MCB to the double socket on either side is approx. the same distance.

Ok, but whether a ring is viable still depends on how long that distance is.

The ring is a tradition which is no longer really necessary with MCBs.

 

[AndyPRK]

diagram looks fine to me.

Though you don't need the 6A MCB. Put these devices onto one of the other circuits.
Could even put the hood onto the lighting circuit if it was accessible

 

[sparkwright]

if you didn't have a ring (second diagram), you would need to use 4mm2 cable rather than 2.5mm2, if using a 32amp MCB.

 

[EFLImpudence]

I should have made that clear.

 

[Lankydan]

Is the 20A DP switch allowed for an oven or do you need a 45A cooker isolator?

 

[EFLImpudence]

If the oven is 20A or less then yes.

 

[EFLImpudence]

Missed yesterday.

If your oven is actually 15A, then you cannot use a socket and plug.
If it comes with a plug, then it won't be 15A.

 

[Lankydan]

If it comes with a plug, then it won't be 15A.

It hasn't arrived yet but it's a 3.45kW single oven which is around 15A isn't it? If it doesn't have a plug, I just need a flex outlet or cooker outlet right?

Thank you so much for your help and advice.

 

[EFLImpudence]

If it doesn't have a plug, I just need a flex outlet or cooker outlet right?

Yes, a 20A flex outlet https://www.toolstation.com/mk-20a-flex-outlet-plate/p79185?searchstr=flex outlet

or cooker outlet which will be 45A https://www.toolstation.com/search?q=cooker outlet

 

[Lankydan]

Thank you EFLImpudence. You are a true legend.