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]

Makes sense to me, I do think that a lot of this accumulated current can be a bit of a myth though.

I work at a site where there are two IT suites each with 20-30 PC's all fed from a TPN DB with a 30ma RCD main switch. It never trips...except when it's tested.

 

[Wilko]

By the looks, the reg makes us responsible for equipment leakage in the installation design. For me to do that, the appliances would need to have a stated and rated leakage current. Or have I misunderstood?
Just now I can't recall working on a domestic dual RCD installation that was tripping for reasons other than a fault.

 

[Phil Thompson]

By the looks, the reg makes us responsible for equipment leakage in the installation design. For me to do that, the appliances would need to have a stated and rated leakage current. Or have I misunderstood?
Just now I can't recall working on a domestic dual RCD installation that was tripping for reasons other than a fault.

Same here, I'd one a fortnight ago, cheap 4way extension lead.

 

[telectrix]

I am not aware of those proposals, are you saying it is proposed that a 63a RCD would be restricted to a load of 21a?.....then presumably a 32a RCBO would be restricted to under 11a?
So a 10kw shower would need a minimum 135a RCBO ?....Sorry if I'm having a blonde moment but that just doesn't make any sense.

as i read it, it's talking about leakage currents not being more than 30% of the mA rating of the RCD, unrelated to load current.

 

[Midwest]

Since my #25 (trying not to big myself up too much here ),it has brought numerous comments and posts on 531.3.2 (draft 18th).

You'd been surprised perhaps, that the draft has only collected a few comments on this new proposed reg, which therefore may see its introduction in the 18th.

In fact the current '531.2 RCDs', will be Over Current Protective Devices. RCDs will be moved to 531.3, as far as I can make out. This includes the reg on unwanted tripping, as well as some other changes; '531.3.1.201 Except in certain special installations or locations (Part 7), for protection against electric shock, there is no requirement to disconnect/switch the neutral in TT or TN Systems'. Haven't noted that before, seem to recall members stating the opposite previously for a TT system (SP RCBO's)?

Apologies for hijacking your thread Murdoch, but you started it

 

[Octopus]

^^ ha ha.

Seeing as nobody can explain why we can fit dual board now, I have come to conclusion that my interpretation of 314.2 is correct in the op and my example stands as a non compliance to the regs.

 

[Octopus]

By the looks, the reg makes us responsible for equipment leakage in the installation design. For me to do that, the appliances would need to have a stated and rated leakage current. Or have I misunderstood?
Just now I can't recall working on a domestic dual RCD installation that was tripping for reasons other than a fault.

It's abundantly clear that the 18th will add further confusion to the regs.

Do the people who dream up these changes actually consider the impact of what they write and add. I don't think so

 

[seltechpc]

I decided to make up a small extension lead with the earth broken out so I can check the earth leakage of various plug in appliances by clamping the L+N.
It was very revealing, I checked 3 Miele appliances and found they were all around 3mA leakage; one of them was a brand new dishwasher. The leakage increased slightly when switched off on the machine. A Neff induction hob I clamped the cable and measured 2mA leakage.
These leakage currents add up and may be the reason that the proposed 18th edition is specifying a limit of 30% of the RCD trip current. Problem is I do not see how a sparky will know what appliances the householder will plug in, and will he have to check items that are hard wired like hobs. I think it is all the filters fitted to modern day electronic appliances that is giving rise to increasing leakage currents.
The only way around this, unless I am missing a trick is to fit all RCBO boards, even then you could easily exceed the 30% RCD current on 1 ring final.

 

[Midwest]

I clamped my own house the other day. PC running, few led lights on, tv on, appliance turned on but not running. Clamp meter's a cheap en, but I had 14mA leakage. But I've have that split across RCD & RCBO's. Went to a job in the afternoon, semi with 1 x lighting, 1 x RFC & electric cooker. 9mA eath leakage.

^^^ ditto

 

[Octopus]

The only way around this, unless I am missing a trick is to fit all RCBO boards, even then you could easily exceed the 30% RCD current on 1 ring final.

Hit, nail and head spring to mind..... I stopped fitting dual RCD boards when AMD3 boards arrived - far, far, far better when something trips.

 

[Deleted member 9648]

^^ ha ha.

Seeing as nobody can explain why we can fit dual board now, I have come to conclusion that my interpretation of 314.2 is correct in the op and my example stands as a non compliance to the regs.

314.2 merely states that due account shall be taken of the consequences of the operation of any single protective device

As the rest of the installation will not be affected by the operation of the device in question at the present time it complies.

 

[Midwest]

Hit, nail and head spring to mind..... I stopped fitting dual RCD boards when AMD3 boards arrived - far, far, far better when something trips.

For a larger property, I'd fit a high integrity CU with 2 or 3 RCBO's. The off the shelf RCBO populated CU's only come seem to come with 6 or so RCBO's, to make one up yourself is a tad expensive?

My own pad, which I did a few years ago, has a RCBO CU and single RCD CU for ono important circuits (314.2 considered ).

 

[Midwest]

I'd give up Murdoch

 

[Octopus]

I'd give up Murdoch

Not yet!

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

Or as I said 314.2 my interpretation is correct!

There's nothing worse than a single RCD up front board ....

 

[Lucien Nunes]

Being pragmatic, I think it is most useful and sensible to have lighting and power in a given area on different RCDs and whilst one might argue about the exact interpretation of 314 it would be poor design not to do this, and hence arguably non-compliant.

The main point of a 30mA RCD is to protect against electric shock, which is most likely to occur when someone has an accident of some kind with a portable appliance. To plunge them into darkness within a fraction of a second of having been shocked, simply on the grounds of economy, is not sensible. I think we get blinkered to this purpose of RCDs because we are so used to being called on to troubleshoot nuisance trips, we don't associate their operation with the moment they cut short a possibly fatal shock that could leave someone in a vulnerable physical condition.

On the subject of convenience, many elderly and infirm people are most at risk on the stairs. They might safely be able to cross the room to turn on the ceiling light if they have been using a table lamp when the RCD serving the ring trips, but would not venture downstairs or run a cable up if the stairwell and room lighting circuits went off too.

It was very revealing, I checked 3 Miele appliances and found they were all around 3mA leakage; one of them was a brand new dishwasher.

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.