secondary 2 way ccu

[GaryMo]

Would you agree that a main switch would perform the function of emergency switching for an installation where it may be necessary to control the supply to remove an unexpected danger?

 

[ericmark]

Reading http://www.bsi-global.com/en/Standa...g/Manufacturing-Standards/BS-EN-60204-12006-/ which relates to BS EN 60204-1:2006 it refers to fixed equipment which would include items like bench grinder but not electrical hazards and is to do with emergency switching of that type of fixed appliance.
If the regulations on emergency switching were to apply to a consumer unit they would need to be yellow with a red switch and be easy accessible i.e. never fitted in cupboard or under stairs or in a locked garage.
You are grasping at straws you know as well as I do that it is a good idea to have a single point isolation and you also know it is not required in the BS7671:2008 regulations. You may find that BS EN 60439-3:1991 requires all consumer units have a single point isolation within the enclosure but not BS7671:2008 for other than for agricultural and horticultural premises. And although I would use a single point myself I can’t tell an ordinary person his electrician has done it wrong when he has not fitted a single point isolator.
Eric

 

[holmslaw]

..

 

[GaryMo]

I'll type it again....

Eric, read it again.

A main liked switch (singular) shall be provided an near as practicable to the origin of every installation as a mean of switching the supply on load and as a means of isolation.

Definitions - Origin of installation
The position at which electrical energy is delivered to an electrical installation.

So, we need a main switch (singular) as near to the main intake as possible to switch the supply on load or isolate the installation.

It's pretty much black and white to me what's required to comply with BS7671:2008.

 

[ericmark]

I have consulted an English graduate as to what it means and my interpretation has been confirmed.
Eric

 

[GaryMo]

Maybe we can employ your graduate friend to write a guide to BS7671?

I'll try and make time today to call the ECA technical helpline to ask their interpretation of 537.1.4

 

[ericmark]

Do remember Hager etc offer a locking option to the covers on the consumer units which when locked stops anyone being able to switch off at the consumer unit in an emergency I am sure if emergency access is required they would be at least a note to that effect on their web site.
Eric

 

[GaryMo]

Eric, the ECA agree with you and not me

Maybe i've been reading too much into 537.1.4 and expecting others to install to a standard set by myself which can't always be the case.

So, there's no set requirement to install a main isolator to serve as a single point of isolation as set out by 537.1.4, it's just good practice according to the ECA (and your good self!)

Nice debate anyway

 

[GaryMo]

Interestingly enough, a similar debate has surfaced over on the IET forums http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=28040&enterthread=y

 

[Spark123]

Sitting on the wall on this one - how could a single point of isolation be applied to an industrial installation which is fed from more than one power source?

 

[GaryMo]

how could a single point of isolation be applied to an industrial installation which is fed from more than one power source?

537.1.6 ?

 

[Spark123]

Yes, it can comply with 537.1.6 however can it comply with 537.1.4?

 

[ericmark]

Thank you for telling me the outcome. And yes I do think single point is a good idea I also like the idea of having the main isolator outside the main consumer unit so the consumer unit can be isolated else where when worked on which I think is an electricity at work requirement.
But I am also a realist and know in most cases you can't do this and just accept what we have.

And yes good debate.

All best Eric