Sub Consumer Unit

[DetlefSchmitz]

The 18th is a part of the Building Regs which are law (criminal law).

Not really...

 

[JohnW2]

The 18th is a part of the Building Regs which are law (criminal law). BS are recommendations. BS are only law when a part of the 18th points to a BS number as being a part of the regs.

What onn earth are you talking about?!

I presume your reference to "the 18th" is a reference to the 18th edition of BS7671 (BS7671:2018) - which, is as you say, is just a Standard whose 'requirements' are not mandatory, and has absolutely nothing to do with any law, criminal or otherwise.

The only relevant law in Part OP of the Building Regulations, and that is just one sentence. Many/most people use compliance with BS7671 as a means of demonstrating compliance with the law (Part P), but that is their choice, not mandatory or 'law'.

 

[hard-work]

Not really...

elaborate.

 

[hard-work]

Electrical regs are a part of the Building regs. Wandering off topic here.

 

[JohnW2]

The stackables only use one Mainswitch in the master CU.

That's what I said - and also that, if they had two, tey would be non-compliant with BS7671.

The only way I can see a non-stackable CU having a sub CU is drilling the bus bar on the master CU after the mainswitch. Other views welcome.

You may well be able to put the additional conductors into the load terminals of the main switch, particularly if there is only one (or no) RCDs

 

[JohnW2]

Electrical regs are a part of the Building regs. Wandering off topic here.

Again, rubbish. See my recent post explaining the relationship between BS7671 (aka 'The Wiring Regs') and Part P of the Building Regs (the only bit of 'law' involved).

 

[DetlefSchmitz]

elaborate.

BS7671 is mentioned as one way to satisfy the requirements but not mandated.

 

[JohnW2]

BS7671 is mentioned as one way to satisfy the requirements but not mandated.

Indeed so. As I wrote (somewhat less succinctly ) ...

.... The only relevant law in Part P of the Building Regulations, and that is just one sentence. Many/most people use compliance with BS7671 as a means of demonstrating compliance with the law (Part P), but that is their choice, not mandatory or 'law'.

In fact, even the mention of the fact that compliance with BS7671 is one way to satisfy Part P only appears ('as guidance') in an Approved Document, so even that does not have 'the power of law' (and therefore, I suppose, 'the law' is not compelled to abide by that statement!).

Kind Regards, John

 

[hard-work]

That's what I said - and also that, if they had two, tey would be non-compliant with BS7671.
You may well be able to put the additional conductors into the load terminals of the main switch, particularly if there is only one (or no) RCDs

So a bus bar lug and a lug for the L tail to the sub CU into the mainswitch incomer. The L tail wire has a lug or a soldered end.

 

[JohnW2]

So a bus bar lug and a lug for the L tail to the sub CU into the mainswitch incomer. The L tail wire has a lug or a soldered end.

As I said, the L conductor might fit into the main switch terminal, without the need for any 'lugs'.

 

[hard-work]

BS 7671 Requirements for electrical installations. is non-statutory.

The Electricity at Work Regulations (EWR) 1989. is statutory.

 

[JohnW2]

BS 7671 Requirements for electrical installations. is non-statutory. The Electricity at Work Regulations (EWR) 1989. is statutory.

Very true, but what has the EAWR got to do with anything we're talking about?

 

[hard-work]

As I said, the L conductor might fit into the main switch terminal, without the need for any 'lugs'.

Legal I am am sure. Frowned up.

Having the sub CU with no incomer means the L tail has to connect to the bus bar - that means drilling it and bolting the L tail onto the bar.

Stackable Wylex CU but all in one unit and very expensive:

The idea is to stack two separate CUs.

 

[hard-work]

Very true, but what has the EAWR got to do with anything we're talking about?

Nothing.

 

[JohnW2]

Legal I am am sure. Frowned up.

If you believe that, you would have to 'frown upon' almost all 'high integrity' CUs - which generally have two conductors (one to feed each RCD) plus a busbar (to feed non-RCD circuits) in the load terminal of the main switch.

Therefore, provided that yours is not a 'high integrity' CU, the main switch terminal should be able to accommodate your 'extra' conductor.