Sub main advice please

['mr2'gd4u]

Thanks, wasn’t taking the pi$$ I’m still on the byb and couldn’t find it...

Its OK.. I still haven't booked my 18th exam. Don't think I'm gonna get a place before Jan either .

 

[Octopus]

537.1.4 A main linked switch or linked circuit-breaker shall be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.

A main switch intended for operation by ordinary persons, e.g. of a household or similar installation, shall interrupt both live conductors of a single-phase supply.

BYB page 154

Which is open to interpretation ... A main switch per fuseboard and per switch fuse could serve to provide the necessary isolation.

If not hundreds of thousands of properties could be deemed dangerous

 

[mossep]

Which is open to interpretation ... A main switch per fuseboard and per switch fuse could serve to provide the necessary isolation.

If not hundreds of thousands of properties could be deemed dangerous

I don't think it would mean properties would be dangerous, just poorly designed.

Would you have the same opinion if you went into the mains room of a large factory and had to shut off the power in an emergency, and instead of having a single main isolation switch, you had a series of 15 randomly placed switch fuses and fuse boards? BS 7671 applies to all setups after all.

 

[DPG]

Not quite the same thing though is it. Two consumer units next to each other do not really create an isolation problem. Certainly not one which means it is essential to install a separate isolator next to them anyway.

 

[Matthew]

MDJ - thanks for your reply. To clarify intent. Split incoming mains and install a CU house side that will feed 16mm to outbuilding. CU in outbuildings supplying one RFC one lighting circuit and 15m2 of UFH and two electric Velux. The reason for T&E into SWA was picked up in a post - for aesthetics as conduit into box outside looks better than trying to get 16mm SWA out and down a wall. Does this answer Qs or have i missed something? Thanks so far all. I was going to install a mains isolated while i was there as currently not one

 

[mossep]

I picked an example at the other end of the spectrum on purpose to be honest. The regulation doesn't say how many fuse board there needs to be before you need an isolator to turn it all off, it just says that every installation needs one at the origin.

 

[Nigel]

Youve changed your tune haha

Exactly what I was thinking.

 

[Octopus]

537.1.4 A main linked switch or linked circuit-breaker shall be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.

A main switch intended for operation by ordinary persons, e.g. of a household or similar installation, shall interrupt both live conductors of a single-phase supply.

BYB page 154

In such a case where there are 2 boards or more, you could argue that 537.1.6 would then apply ................... (BYB p 154)

 

[Wilko]

In such a case where there are 2 boards or more, you could argue that 537.1.6 would then apply ................... (BYB p 154)

Can you believe they've deleted 537.1.6 from BBB. I think we will have the same label at 514.15.1 and perhaps 537.2.7 (new) which says isolators to be clearly identified.