Is an RCBO an adequate replacement for an isolator?

Yep. One RCBO for the electric shower, another for the bathroom lights extractor fan/ shaver point etc and maybe a third for say an an electrical heated towel radiator that runs off the sockets.

As long all bathroom circuits are RCD protected and the main equipotential bonding is done then you can bin the bathroom supplementary bonding.

Adam

Reply to
ARWadsworth
Loading thread data ...

Then each and every appliance flex must be capable of tripping the RCBO of that circuit in event of a fault.

Reply to
Dave Plowman (News)

A safety isolator should be within easy reach of the appliance. The CU could be several floors away.

Reply to
Dave Plowman (News)

To relax the requirement for supplementary bonding under the 17th edition, they don't need to be on the same RCBO (or RCD). There are some pre-requisites: the main EQ bonding must be in place, and the trip threshold for the RCDs protecting the "special location" circuits must not exceed 30mA. The RCD does not need to be local to the special location either - in the CU is fine.

Reply to
John Rumm

Its worth noting that all the new sensible price RCBOs tend to be single pole devices. However since this is not being used for isolation and only fault protection, there is no benefit in having double pole devices.

No need for it to be on the same RCD.

They need double pole RCBOs because they don't maintain the same degree of polarity control that we do. Circumstance will dictate whether radial or ring topology is preferable, but you can't elevate one above the other since they both have pros and cons. Ring circuits tend to out perform radials in the majority of common fault scenarios for example. Radial circuits are better suited to non diverse fixed loads.

Reply to
John Rumm

Reply to
John Rumm

Silly no. Cheap - can depend on the circumstances, but cheap is not necessarily a bad thing.

The reasons why they were created and why they are still used are very different. Ring circuits are far more appropriate now than they were when conceived.

Huh?

Appliances with concealed sockets should have separately accessible isolation switches.

There is no need for fused spurs in most kitchens. Having said that, a switched fused spur is not really aesthetically less pleasing than a plain isolation switch.

Appliance fuses in general very rarely blow unless there is a fault in the appliance, and in that case the chances are you will need to pull it out from its utility space anyway to fix it.

Reply to
John Rumm

Indeed. Which is why the DP devices are not used that often. The 17th edition rules for cable protection made RCBOs more desirable (or at least multiple RCDs[1]). The manufacturers have responded to that need and also the one of conserving CU space by introducing far more competitively priced single width SP RCBOs. These are still not exactly cheap, but at under £20 in many cases are affordable. (still MCB prices are under £2 in some cases now,

While one would be unlikely to install a rewireable fuse carrier these days, there is nothing to stop you using cartridge fuse carriers (and these can be handy in some circumstances).

Reply to
John Rumm

ARWadsworth wibbled on Wednesday 11 November 2009 17:25

Ideally (but slightly unfairly on the contractor as it involves potentially lots of work for which they might not get paid if the customer backs out):

They assess the installation FOC and produce a checklist of faults on top of the CU work and don't do anything until the additional work and price has been agreed, as well as the price for the CU.

What you don't want as a customer is:

CU changed happily. Then they test the final circuits to fill out the EIC, uncover a multitude of problems (real or invented) and then apply an exhorbitent charge to fix them otherwise they cannot do the Part P notification and you end up with a non registered and questionable installation.

Adam might be kind enough to suggest how this sort of scenario is handled fairly in the real world?

Cheers

Reply to
Tim W

A full electrical PIR on the house electrics at an agreed price before changing the fuse box to a 17th edition CU is the fairest option. A FOC assessment on the house electrics is only worth what you pay for it. I do not do FOC assessments before changing a CU.

Only a madman, conman or cowboy would try to change a fuse box for a 17th edition CU without testing the circuits before fitting the new CU.

Adam

Reply to
ARWadsworth

Like you agree to pay =A31800 cash for a new lighting circuit or I'm not coming out? :-)

Before installing RCDs for the first time...

1 - Do insulation test first 2 - Check lighting for borrowed neutral/live (often very obvious)
Reply to
js.b1

Like you agree to pay £1800 cash for a new lighting circuit or I'm not coming out? :-)

I'm not "coming out" for any amount of money or any lighting circuit:-)

Before installing RCDs for the first time...

1 - Do insulation test first 2 - Check lighting for borrowed neutral/live (often very obvious) 1.Yes the insulation test is very important. Probably the most important test. 2 If not easy then a clamp meter shows the borrowed neutrals when you are suspicious about an existing install.

Adam

Reply to
ARWadsworth

There never was 'unmetered' power in the UK - nor was it ever likely. Just the usual political spouting off. Nuclear power may have lowish running costs in terms of the fuel needed - but the capital costs have always been high. And would have to be paid for somehow.

Reply to
Dave Plowman (News)

Re "unmetered" elec, that always amused me.

1 - Nuclear will just inflate energy company profits & taxation for HM Treasury 2 - Any incentive for E7 making a substantial comeback must be eliminated because it would collapse the grid infrastructure, realise even if just the oil burning people moved to E7 the grid could not withstand it (never mind the generating plant) 3 - Investment in plant & grid is either non-existent or hopeless, "The City Does Not Do R&D or Maintenance" - Railways-II 4 - Gov't Investment projects are a blank cheque for the corrupt, paid by the stupid, monitored by the incompetent, answerable to the next government which can blame the previous government, providing employment for innumerable quangos and art journalists too thick to even spell science without a PR explaining it to them with coloured bricks and 17 training courses, two marketing consultants, one advertising consultant and finally their children until educationalists saw that off.

UK Gov't & Oligarchy long ago decided having Lost The Empire they would just sponge off the remaining population rather than create the infrastructure & investment for economic leadership matched to a portfolio of talents. I always remember one multi-million pound business owner screaming "it is because of this technology nonsense that we have to spend money on investment rather than ourselves", then dumped the clutch with engine screaming in his audi quattro. Summed it up really, when UK had an empire it appears the idea was no-one competed - Oligarchy merely assigned it to the appropriate individuals. Then someone decided to compete, globalisation has little respect for the hereditary epigeneologists - and likewise the hereditary can continue until eventually globalisation defeats nationalism re lost social contract to be replaced of course by religion (jews want an eye for an eye, koran not far off, christianity makes you wait until you are dead hence preferred by Bush & Blair).

The bailout for a move to nuclear electric would be smart-meters teleswitching CO2 heatpumps.

Reply to
js.b1

You are Ian Hislop and I claim my £5!

I'd consider you to be cynical, except that the above is true and I agree with it. Pity that it can't be repeated as widely and frequently as GordAlmighty regurgitates his own faeces.

Reply to
PeterC

No one else adopted it except the Irish.

Sometimes fuses just fail. The Continentals do not have fuses in their plugs so no problem in removing a heavy appliance.

You clearly have a little clue. No one else adopted our ring system. Amazing eh!

Reply to
Doctor Drivel

They proposed and it was on public info films. See one.

Reply to
Doctor Drivel

That is total drivel.

Reply to
Doctor Drivel

Not quite true - there are unmetered connections, usually for streetlighting etc, where the cost of metering would be disproportionate.

And that's only the legitimately unmetered connections, of course!

Owain

Reply to
Owain

Doctor Drivel wibbled on Thursday 12 November 2009 17:58

IIRC our ring system was primarily adopted as a way to turn a couple of 15A radials into a 30A circuit with more 13A sockets on - ie an upgrade path without the need to throw away a couple of perfectly good bits of whatever the imperial of 2.5mm2 was. It also saved on copper.

Anyway, a system that allows loads of sockets, and upto 2 and a bit heavy appliances and umpteen million trivial devices to be plugged in at random locations without having to use a rediculously massive cable is a pretty good system.

Reply to
Tim W

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.