Remote Isolator On Locked Disboard/CU

[bailes1992]

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.

 

[davesparks]

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?

Leave the building by the nearest exit and operate the fire alarm.

 

[Shoei]

Activate the fire alarm and get out?

Good advice, I don't have a fire alarm in my house but I do have an extinguisher and would prefer to stop the house burning down if I could do it safely. I'd be a bit miffed if my friendly electrician had locked down the CU and wandered off.

 

[davesparks]

Good advice, I don't have a fire alarm in my house but I do have an extinguisher and would prefer to stop the house burning down if I could do it safely. I'd be a bit miffed if my friendly electrician had locked down the CU and wandered off.

Why would you have a lockable CU in a house?
This thread is obviously concerned with non-domestic installations where lockable DBs are quite common, so why drag it off track with domestic nonsense?

 

[Spoon]

But the OP hasn't stated where these CU's will be mounted and what the building is. Just that students can get to the CU's.
Nothing wrong with locking CU's. All depends on the circumstance.

 

[davesparks]

But the OP hasn't stated where these CU's will be mounted and what the building is. Just that students can get to the CU's.

No he hasn't explicitly stated what the building is, but he has stated that there are TP and SP DBs so it doesn't take a genius to work out that it isn't a domestic installation.

 

[bailes1992]

But the OP hasn't stated where these CU's will be mounted and what the building is. Just that students can get to the CU's.
Nothing wrong with locking CU's. All depends on the circumstance.

3 Phase boards locked in risers for lighting and power.

Each communal kitchen has a single phase board in the kitchen feeding final circuits feeding all the kitchen accessories (cooker, fridge, freezer, oven, dishwasher etc). These boards are accessible with a locked front cover... if that makes sense.

 

[Shoei]

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?

You design the system to include proportionate measures to support a safe response. For example those public buildings often have an external isolator for the emergency services.
In the context of BS7671 the CU isolator may or may not be an emergency device, the designer must make that decision and apply the reg's accordingly.

 

[Shoei]

No he hasn't explicitly stated what the building is, but he has stated that there are TP and SP DBs so it doesn't take a genius to work out that it isn't a domestic installation.

bailes1992, didn't ask about installations, domestic or otherwise, he asked why Electrium would attach a label to a CU stating that it must have a separate isolator if it was to be locked.

 

[snowhead]

But what is your point?

I'm not trying to make a point about why the reg exists or how it should be interpreted, I'm just offering a possible explanation to why the DB has a sticker in it.

My experience over the last 51 years working on Commercial sites is that around 50% of D.B's and main panels are in locked rooms or cupboards and the majority of occupants wouldn't know where the room was let alone the key, so emergency isolation in those cases isn't "readilly available".
Either Emergency isolation refers to something else or hundreds of people doing Periodic inspections don't understand the meaning.

 

[davesparks]

I'm not trying to make a point about why the reg exists or how it should be interpreted, I'm just offering a possible explanation to why the DB has a sticker in it.

My experience over the last 51 years working on Commercial sites is that around 50% of D.B's and main panels are in locked rooms or cupboards and the majority of occupants wouldn't know where the room was let alone the key, so emergency isolation in those cases isn't "readilly available".
Either Emergency isolation refers to something else or hundreds of people doing Periodic inspections don't understand the meaning.

The main switch of a DB is rarely, if ever provided as a means of emergency isolation.
If emergency isolation is required then that would have been identified by a risk assessment and suitably rated emergency systems designed and put in place.