Does this comply with 314?

[Octopus]

Been at a place today.......... brand new loft conversion.......... so an additional CU has been fitted for the lights and sockets ......................

Thinking specifically about 314.2 :

I would say that it doesn't............

Opinions please

and more to the point, this conversion probably cost about £45k so using RCBO's wouldn't have been noticed................

The last one I saw was where a new single RCD board had been used for the entire house and loft conversion.............. why do people do this?

 

[Deleted member 9648]

I think the view that the installation in the original post is non compliant is being rather overlapped with the view that there is a better design alternative.
The two are entirely different things. Yes there is a better design alternative, but given that there is a division of circuits over the installation as a whole, it is compliant.
Like a lot of Bs7671 314.2 is open to various interpretations and does not specifically state that circuits within the same room must not be subject to loss from a single protective device.

 

[Risteard]

I need somebody to remind me why we ditched split load boards and introduced dual RCD's - somebody must have some memory of this?

Because under the 16th Edition we didn't tend to RCD protect everything.

 

[Ian1981]

SPlit load dual rcd consumer units came out when the 17th edition introduced the requirement for more rcd protected circuits for multiple reasons as with the 16th cables where not required to have additional protection to them where buried in walls <50 mm

 

[seltechpc]

Really? The maximum permissible on a 13A plug is 3.5mA, I would be most surprised to see that much leakage from any domestic appliance or have they gone silly with filtering these days? I don't PAT any domestics but I see a lot of PAT results from industrial equipment and no single piece of kit ever reaches 3mA. Even the media systems that I build, with maybe 20 pieces of equipment built into a rack all run from one plug, rarely reach 2mA.

I decided to recheck these readings and the results were 1.2mA, 1.3mA and the newest appliance was 1.96mA. A bit red faced at quoting 3mA but these do add up to almost 4.5mA. The hob was around 2mA which starts to seem these electronic appliances with various filters to meet EMC specs are increasing the leakage currents to levels where it can lead to unwanted tripping of the RCD's, even with a high integrity CU.
Add more appliances and a few computers and little thought given to which rings they are plugged into can give rise to nuisance tripping.

 

[Octopus]

SPlit load dual rcd consumer units came out when the 17th edition introduced the requirement for more rcd protected circuits for multiple reasons as with the 16th cables where not required to have additional protection to them where buried in walls <50 mm

I realise this but why a dual RCD and not a single up front RCD?

 

[Midwest]

I realise this but why a dual RCD and not a single up front RCD?

I don't think this kind of subterfuge, is going to work Murdoch

 

[Ian1981]

Then you run the risk of losing all your power if the rcd trips.
At least with 2 you don't loose all power to all circuits.
Of course you can do that arrangement if you wish but I know you wouldn't
I haven't read the full thread so I feel I'm missing the point?

 

[Ian1981]

Or do you feel only rcbos are the only solution?
Each individual circuit?

 

[Octopus]

Then you run the risk of losing all your power if the rcd trips.
At least with 2 you don't loose all power to all circuits.
Of course you can do that arrangement if you wish but I know you wouldn't
I haven't read the full thread so I feel I'm missing the point?

Have you read my opening post ?

 

[Ian1981]

Db for the loft sockets and lights on one rcd.
Your worried about loss of power to the whole loft.
I'd say that it's fine.
The rest of the house wouldn't be affected I wouldn't be worried about it.
I see the point in individual rcbo protection but individual rcd protection for all circuits isn't a requirement tho certainly not prohibited.
Upto the individual installer I'd say.

 

[Deleted member 26818]

I think the reason we went from split boards to dual RCD boards is simply down to manufacturers.
Cheaper to alter existing stock to dual RCD than to bin it all and start manufacturing high integrity boards.

 

[Octopus]

Db for the loft sockets and lights on one rcd.
Your worried about loss of power to the whole loft.
I'd say that it's fine.
The rest of the house wouldn't be affected I wouldn't be worried about it.
I see the point in individual rcbo protection but individual rcd protection for all circuits isn't a requirement tho certainly not prohibited.
Upto the individual installer I'd say.

So why don't we fit single up front rcd boards any more then?

 

[Deleted member 26818]

So why don't we fit single up front rcd boards any more then?

Did we ever?

 

[Ian1981]

So why don't we fit single up front rcd boards any more then?

Think I've already answered that one murdoch.
Risk of TOTAL loss of power as opposed to partial loss with a dual board.

 

[Ian1981]

Did we ever?

I never

 

[Octopus]

Risk of TOTAL loss of power as opposed to partial loss with a dual board.

Which neatly brings us back to my opening post ...... I rest my case.

 

[Ian1981]

Which neatly brings us back to my opening post ...... I rest my case.

but the rest of the house still functions yes?

 

[Midwest]

Still go back to the original design for this install. Single RCD for both lighting & power for a loft conversion. Would 'you' put those circuits on the same RCD in the CU, if there was space?

 

[Deleted member 26818]

The thing is Murdoch, 314 requires us to minimise inconvenience, it doesn't require us to eliminate it.

 

[Ian1981]

Why does the loft need to be on its own circuit as in lights in particular?