UK Sub board

[sirsparksalot]

Suggestions please. I am planning on putting a new consumer unit in my kitchen fed off my existing consumer unit. Probably off of a 50a MCB. I was thinking of a main switch 63a, 6 way then using rcbo's for each circuit. Does anyone know if it is ok to swap a 100a main switch for a 63a? Does anyone know if a 63a RCD would be better than a 63a main switch if I am going to use rcbo's for each circuit? My existing consumer unit has an 100a main switch controlling some circuits and an 80a RCD controlling the others. The mains is going into a Henley block with a 60a fuse. Unfortunately there is no free terminals in it for me to go into a fused switch before I go to my kitchen sub board. Does anyone know if it would be better to come off the 100a main switch side and have a 63a RCD at the kitchen sub board? Any suggestions are appreciated.

 

[Taylortwocities]

I am sorry. These are such basic questions that I am going to suggest that you should not be contemplating doing this work yourself. It is all new circuits, therefore it is notifiable work, so you are going to need a registered electrician in any case.

Find a local one here Home - https://www.electricalcompetentperson.co.uk/

 

[acutting]

Hi there,

Firstly there is no point in swapping the main switch on the sub board. The switch rating, is it's maximum rated current and with what you are suggesting, it would only ever get to around 50A before the upstream MCB would trip.

You need to rethink this. As your main consumer unit is RCD protected, an RCD or RCBO is unlikely to trip before the one on the main board.

Also on the sub board, an RCBO is effectively an MCB and an RCD in one unit. Having an RCD and RCBOs is effectively pointless

What is the purpose of the sub board? Wouldn't it be worth swapping out your main consumer unit giving you more space.

If the sub board is the only option then you'll be looking at 10mm SWA from the main board to the sub board. Moving the 50A MCB so it's non RCD protected.

 

[David Prosser]

Does anyone know......?
Does anyone know .........?
Does anyone know .............?

Yes lots of people know but WTF ? you should know !

 

[sirsparksalot]

Hi there,

Firstly there is no point in swapping the main switch on the sub board. The switch rating, is it's maximum rated current and with what you are suggesting, it would only ever get to around 50A before the upstream MCB would trip.

You need to rethink this. As your main consumer unit is RCD protected, an RCD or RCBO is unlikely to trip before the one on the main board.

Also on the sub board, an RCBO is effectively an MCB and an RCD in one unit. Having an RCD and RCBOs is effectively pointless

What is the purpose of the sub board? Wouldn't it be worth swapping out your main consumer unit giving you more space.

If the sub board is the only option then you'll be looking at 16mm SWA from the main board to the sub board. Moving the 50A MCB so it's non RCD protected.

Thanks for the advice. Do you not think a 10

Hi there,

Firstly there is no point in swapping the main switch on the sub board. The switch rating, is it's maximum rated current and with what you are suggesting, it would only ever get to around 50A before the upstream MCB would trip.

You need to rethink this. As your main consumer unit is RCD protected, an RCD or RCBO is unlikely to trip before the one on the main board.

Also on the sub board, an RCBO is effectively an MCB and an RCD in one unit. Having an RCD and RCBOs is effectively pointless

What is the purpose of the sub board? Wouldn't it be worth swapping out your main consumer unit giving you more space.

If the sub board is the only option then you'll be looking at 10mm SWA from the main board to the sub board. Moving the 50A MCB so it's non RCD protected.

Thanks for your reply. Do you not think a 10mm SWA would suffice as I will only be having a lighting circuit, a ring for power, a radial for a cooker and a radial for a boiler? I may add an external lighting circuit down the line.

 

[acutting]

Thanks for the advice. Do you not think a 10

Thanks for your reply. Do you not think a 10mm SWA would suffice as I will only be having a lighting circuit, a ring for power, a radial for a cooker and a radial for a boiler? I may add an external lighting circuit down the line.

It's down to the spark designing the circuit, to work out the appropriate loads, to then select appropriate cable to then work out what over current device to install.

Your installation also needs surveying, you state the Henley block is already full of tails. So will adding extra load put the main fuse at risk?

The question is why? It's likely to be cheaper and easier to upgrade the main consumer unit.

 

[Taylortwocities]

The question is why? It's likely to be cheaper and easier to upgrade the main consumer unit.

Also notifiable work requiring a competent and registered electrician.

 

[Andy78]

Your profile states NVQ3 qualified but your posts indicate that you have the electrical knowhow of a spam butty. Something's not right here.
But what I can say is the advice given about getting in someone who knows what they are doing should be followed and that no forum member should be encouraging you further in doing this yourself.

 

[DPG]

No shame in knowing when you're out of your depth.