rcd as main switch

[DurhamSparky]

it all depends how you interpret the regs at end of day! every body has there own version and best way!

me personally i still come accross lots of ELCB and 100/30 ma RCD on tt installs all the time! 9/10 they have no problem!

 

[SimpleSimon]

Hmm. Its like s_d said, SHOULD is the operative word. I can't see the problem, a main switch is only an isolator and provides only Overcurrent protection, if your RCD main switch is a BS61009 (RCBO) than this is the same thing?

And it's not sole means of protection as ADS is still in place.

 

[IQ Electrical]

I've seen it when the RCD is used as the main switch for a economy 7 supply but a main linked isolator is found downstream in the meter tails. This must be acceptable as this would than count as the main switch?

Also, table 53.2 states an RCD can be used for isolation?

You mean upstream in the meter tails.

The reg's don't specifically mention 'an rcd main switch' but make a general reference to circuits being divided to avoid hazards and minimise inconvenience in the event of a fault.

 

[SimpleSimon]

True.
(and yes I mean upstream, it's been a long day.) But if you have a dual board, with the main switch RCD protecting E7, it still minimises hazards as the fault would only appear on the heater/ immersion.

 

[IQ Electrical]

Yes and with the exception of hypothermia, there'd be no danger

 

[SimpleSimon]

Well................hypothermia is this weather would be a consideration!!

 

[bus-nut]

I have just been looking for this in the regs and im buggered if i can find it, i was led to beleve you couldnt use RCCB as a main switch. I have got a job to do it has an old wylex skeleton board and along side it is a small shower ccu 16mm tails going into an RCCB. i have wired the kitchen and was going to change the carcass of the shower unit so i could add the kitchen circuits in without touching the exsisting wylex rewirable board. And because there is two boards the main isolator i beleve should go before both boards but again buggered if i can find that in the regs, if anyone one could point me in the directions of these reg numbers etc id be greatfull. Im stuck at homeIf this is the case why do they sell these shower units/ccu's with just the rccb?? getting over a back operation and thought it would be a good idea to do a bit of swatting and these were the things i was going to check out.

 

[IQ Electrical]

I have just been looking for this in the regs and im buggered if i can find it, i was led to beleve you couldnt use RCCB as a main switch. I have got a job to do it has an old wylex skeleton board and along side it is a small shower ccu 16mm tails going into an RCCB. i have wired the kitchen and was going to change the carcass of the shower unit so i could add the kitchen circuits in without touching the exsisting wylex rewirable board. And because there is two boards the main isolator i beleve should go before both boards but again buggered if i can find that in the regs, if anyone one could point me in the directions of these reg numbers etc id be greatfull. Im stuck at homeIf this is the case why do they sell these shower units/ccu's with just the rccb?? getting over a back operation and thought it would be a good idea to do a bit of swatting and these were the things i was going to check out.

I listed the reg numbers back in post 2:

It is not good practice to provide a single RCD on the supply to a complete distribution board/consumer unit, which may have lighting circuits, etc., as operation will interrupt the whole building supply. Regulation 314.1(i) requires installation circuit arrangements to be such that hazards are avoided and inconvenience minimized in the event of a fault. It can be argued that protection of an installation by an RCD is not related to the ‘circuit’ definition in Part 2 of BS 7671 and Regulation 531.4.1 makes specific reference to a single RCD for a TT installation. However, the decision to provide a single RCD, to use a split distribution board/consumer unit or to use RCBOs must be taken only after due consideration of all the relevant factors, including convenience and maintenance, and not just initial costs. For example, elderly or infirm persons may not be able to gain access to, or reset, an RCD. A single 30 mA RCD should normally not be installed at the origin of the installation.

As for the single point of isolation, try 537.1.4

 

[bus-nut]

cheers for that i read your bit in post 2 earlier i know its not good practise for inconvenice i was just imterested in checking it out in the regs book...can you tell im bored at home ha ha

 

[IQ Electrical]

cheers for that i read your bit in post 2 earlier i know its not good practise for inconvenice i was just imterested in checking it out in the regs book...can you tell im bored at home ha ha

It's like many reg's in that there is not a black and white answer but general guidance to allow us as competent persons to assess any risk before completing a design.

 

[bus-nut]

very true.

 

[Had8Lives]

Steamboat, I've never had a problem with flyleads on RCBOs, usuallt there's too much flylead, but if it's 4/5 circuits it may have to be a 10 Way Enclosure anyway. Loads a room!

 

[Des 56]

A main switch should be provided to isolate the whole of the installation,that is accepted

The follow on to that, there is no requirement for a property to have a single means of isolation because, it can consist of more than one installation

In the case where the shower unit has its own supply tails and consumer unit and the Wylex is seperate,there is no requirement to fit an isolator to cover these two seperate installations,as long as each installation has a main isolator,the propertry can have more

 

[pactrol]

Hi
I think the debate on rcd as a main switch is answerd on page 24 of your on site guide

 

[Engineer54]

Anyone used a dedicated Main Switch/RCBO box which is any good? I don't like shoe-horning RCBOs into a 'standard' box alongside RCDs/MCBs...the RCBO fly leads never seem to be long enough. I think Denmans do one but never used one....

Strange your saying that, ....Most complain of these neutral/F/earth fly leads being too Long and are not sure if you can cut them to length!! (You can by the way!!)