Remote Isolator On Locked Disboard/CU

bailes1992 · Nov 19, 2018

Afternoon All,

Maybe an odd question. For the last 8 years I've been in this industry I have always fitted single and 3 phase disboard/CU's with locks and no remote isolator other than on a locked main panel.

I'm on a new job where we are using a mix of Siemens 3 phase boards and Crabtree single phase boards, all of which have a sticker inside them.

"TO COMPLY WITH BS7671 All consumer units that are intended to be locked after installation must be supplied via a separate means of isolation fitted adjacent to the unit"

Anyone able to shed any light on this? Is it correct? What regulation states this?

A lot of these boards will be accessible to students. You can only imagine the havoc students would cause with a fully accessible isolator.

[ElectriciansForums.net] Remote Isolator On Locked Disboard/CU

Andy78 · Nov 19, 2018

Contact Electrium technical and ask which regulation they refer to. Don't have the time to look it up but my first thoughts would go to emergency switching ?

bailes1992 · Nov 19, 2018

Andy78 said:
Contact Electrium technical and ask which regulation they refer to. Don't have the time to look it up but my first thoughts would go to emergency switching ?

That's my next port of call. It would have been nice to phone up confidently and ask why they're making stuff up though.

davesparks · Nov 19, 2018

This looks like the beginning of another great myth which will soon be turning up on EICRs everywhere.

You can almost see the future on this one, hundreds of DBs with cheap isolators retrofitted to them with dodgy crimp connections to extend the feeds and contacts burning out all over the shop.

Spoon · Nov 19, 2018

Only thing I can find is this: but it's stating that the isolator should be locked away..

Silly Sausage · Nov 19, 2018

I'm thinking 537.1.4 & 4 here.
A single, locked CU, wouldn't really satisfy the above.

Spoon · Nov 19, 2018

EDITED..... Ignore... Should have looked at 17th Ed.

snowhead · Nov 19, 2018

Emergency Switching, 537.4.2.5

bailes1992 · Nov 19, 2018

snowhead said:
Emergency Switching, 537.4.2.5View attachment 45854

"Where a danger could occur" is far too vague for my liking. I could understand workshops or boiler houses where maintenance might be occurring, not accommodation.

Your talking about a location where every single phase final circuit is RCBO protected. Would an isolator really help any situation?

snowhead · Nov 19, 2018

Dangers come in a variety of known and as yet unkown forms.
Presumably it's written vaguely to cover any current or future eventuallity.
RCBO protection may not be on all circuits in all installations.

For example in Student accomodation,
A Brown (or Black or Grey) cable hanging out of a light fitting in a corridor with the end of the cable showing copper.
Does that present a Danger?

bailes1992 · Nov 19, 2018

snowhead said:
Dangers come in a variety of known and as yet unkown forms.
Presumably it's written vaguely to cover any current or future eventuallity.
RCBO protection may not be on all circuits in all installations.

For example in Student accomodation,
A Brown (or Black or Grey) cable hanging out of a light fitting in a corridor with the end of the cable showing copper.
Does that present a Danger?

Brown, black and grey cables are all line colours so should be treated as such unless marked otherwise.

Having previously had a nasty belt from neutral to earth I'd also argue a blue cable would present a danger.

I still don't see how an external isolator would help?

What happens in more public areas where boards are locked in cupboards? Do we start fitting emergency stops everywhere with contactors on the supply to the board?

davesparks · Nov 19, 2018

snowhead said:
Dangers come in a variety of known and as yet unkown forms.
Presumably it's written vaguely to cover any current or future eventuallity.
RCBO protection may not be on all circuits in all installations.

For example in Student accomodation,
A Brown (or Black or Grey) cable hanging out of a light fitting in a corridor with the end of the cable showing copper.
Does that present a Danger?

Yes that presents a danger, or should at least be assumed to present a danger until proved otherwise.
But what is your point? Are you saying that there should be an accessible isolator adjacent to a locked DB in case this situation occurs?

Shoei · Nov 19, 2018

It seems fair enough to identify the CU isolator as an emergency device. For example a room contains smoke and a smell of burning with no obvious source. What's the first-line response?

bailes1992 · Nov 19, 2018

Shoei said:
It seems fair enough to identify the CU isolator as an emergency device. For example a room contains smoke and a smell of burning with no obvious source. What's the first-line response?

So what happens in public buildings where boards are fitted in locked risers and store rooms? Do we put emergency stops in? Rotary isolators outside the doors?

westward10 · Nov 19, 2018

Shoei said:
It seems fair enough to identify the CU isolator as an emergency device. For example a room contains smoke and a smell of burning with no obvious source. What's the first-line response?

Activate the fire alarm and get out?