Kitchen sub main

[cadspark]

I'm on a rewire and am looking at running a sub main for the kitchen circuits because of the house layout it's easier do it this way. I'm running in 10mm t/e from a 50a RCBO to a main switch sub board. From this board I will have cooker 32a, A1 socket radial 32a, 6 amp lighting.

Your thoughts would be appreciated.

 

[telectrix]

will the cpc in the 10mm T/E be sufficient csa. ? may have to run separate 10mm G/Y.

 

[malcolmsanford]

The 10mm is a bit squeaky on that 50amp RCBO, unless it is clipped direct erection method C. All other methods are well below 50amps

As Tel said the CPC might be a little small espicially if it's a 10mm/4mm.

Also if you fitting a sub board I think I might have gone down the road of appliances on their own 16amp radial and just another 16amp radial for the power sockets.

 

[cadspark]

10mm will be ref C. I was thinking of either 6 or 10mm as additional earth.

 

[telectrix]

use 10mm cpc. little cost difference. the 10mm ref.c will be fine on a 50A.

 

[Engineer54]

If the kitchen didn't need a sub-main CU previously, it doesn't need one now!!!

Rewire the kitchen in the conventional manner, a standard sized house doesn't warrant scattered CUs just because it's more convienient for the electrician...

 

[telectrix]

If the kitchen didn't need a sub-main CU previously, it doesn't need one now!!!

Rewire the kitchen in the conventional manner, a standard sized house doesn't warrant scattered CUs just because it's more convienient for the electrician...

unless of course the kitchen is a remote building, then we can have a whole new discussion on exporting PME .. hehehe.

 

[cadspark]

If the kitchen didn't need a sub-main CU previously, it doesn't need one now!!!

Rewire the kitchen in the conventional manner, a standard sized house doesn't warrant scattered CUs just because it's more convienient for the electrician...

The kitchen is at the back of a stone built cottage with exposed beams and so nowhere to hide cable under floorboards. The incoming supply and main board are at the front of the cottage. The property had trunking and surface mounted wiring all over which the new owner hates so to avoid having multiple cables clipped to the beams i'm bringing the 10mm into the kitchen to keep wiring as discreet as possible. There will only be wall lights to avoid cables clipped to beams and he is insistent on no mains powered smoke alarms.

 

[telectrix]

ah, the plot clears. reason for sub-main becomes apparent. just wondering if you could squeeze 10mm T/E and a 10mm G/Y into 1" brown minitrunking to blend with the beams. you would need to position your kitchen CU carefully to avoid steam and grease.

 

[pushrod]

Mmmh... why the need for a larger cpc?

IMO if the circuits are designed correctly for instantaneous disconnection ie Zs values for circuits within regs max values , then a 4mm cpc should have masses of lee way for fault currents.

What is the earthing arrangement for the installation?
(it is late mind and the wine has been drunk lol)

 

[telectrix]

it would all depend on the PEFC and the adiabatic equation.

 

[pushrod]

it would all depend on the PEFC and the adiabatic equation.

That's what i was thinking - so even on a TN with D type breakers if you had a 20 x 50A fault current then cpc size need only be 2.74 mm -( not calculating it just looking it up in a table) and with B types it's even less :wink5:

 

[Engineer54]

unless of course the kitchen is a remote building, then we can have a whole new discussion on exporting PME .. hehehe.

Very true!!! lol!!


Cadspark,

OK, I'll give you that one, That's a good enough reason in anyone's book!!! lol!!!

Just that i hate to see scattered CUs throughout normal standard sized houses, when there's no need for them....