Could you rewire a domestic without RCD protection

[Manator]

I do not think it is a farce, if I really wanted I could eliminate the use of RCD socket outlets providing I had a very good reason for doing so and was no less safe if it was excluded. The point of the excersise was to look at the design and see if it can be done, a very expensive rewire could if desired be totally without RCD even on sockets. If you look at any regulation there is often no black and white you can use this to verify your designed circuits.

I have just fitted a fibreoptic lighting system at a very great cost, I do not like it but the clients are over the moon. At no time did I imply to ignore manufacturers instructions about the use of a RCD, indeed if I had to design a house without RCD I would insist on the shower to be fed from the boiler and advise against the use of electric.

All I can say is that it got me thinking, and it looks like some others thought about it.

The question is an exersise, nothing more.

 

[kme]

I think you provided a thought-provoking discussion Manator. Irrespective of the "its a waste of time / pointless / farce" comments, it DID throw up quite a few interesting posts, and I imagine a few members have actually got their books out and looked at them over the course of the thread, which can only be a good thing - I think we`d ALL agree on that.

Canoey raised an interesting point about the RCD effectiveness, as far as end-user testing (or lack of) is concerned. It remains the single biggest cause of RCD failure. The question is, how do we combat it? Customers, as a whole, are NEVER going to intentionally disconnect their installation, no matter how much we "educate" them on the benefits / necessity. They`ll just forget to do it - its human nature, unfortunately.

Does a question care if it is rhetorical? ( don`t answer, that is a rhetorical question itself).

Thanks Manator - I understand the reasons for posting the thread, even if others didn`t quite "get it".

KME

 

[sellers]

I did get this thread but sadly I was expecting an answer, I couldn't find a way of combating the need for an rcd on a socket intended for general use and was looking forward to learning a way in which it was possible. So a bit of a let down on that part.

 

[Manator]

One interesting part of any regulation is the completion of any EIC, why do you think there are boxes for departures and deviations IF we are not allowed to depart from said regulation.

There have been various audits into the effectiveness of RCD's, when apparently faulty ones have been removed and tested on the bench about 2% worked without any other reason other than the removal and transit rid the mechanical action of any problem. Another 90% worked when the rcd was subject to testing. Conclusion from this was that user lack of regular testing caused the rcd to fail when needed most, however they also concluded that removal of any rcd was not a good idea, and the percentage of failures was in total very small.

 

[binky]

My initial response was to point out that even 12V circuitry requires RCD protection in special locations.However, I then realised that you are quite correct.

BS7671 allows us to make departures from the Regulations, if we as the designer consider the departure offers the same degree of safety as would be achieved by compliance with the Regulations.

So are you saying 12v lighting needs RCD or not? Can't see how regs say it does - if 240V is not in the room, it isn't in the special location ergo no RCD.

 

[spinlondon]

BS7671 requires circuits of special locations to be RCD protected. There is no exception for ELV.

The term used is circuits 'of' special locations, not circuits 'in' special locations.

So yes I am saying that 12V lighting would need an RCD, in order to comply with BS7671.

 

[Manator]

I did get this thread but sadly I was expecting an answer, I couldn't find a way of combating the need for an rcd on a socket intended for general use and was looking forward to learning a way in which it was possible. So a bit of a let down on that part.

Sorry Sellers, indeed my original intention was to provide each regulation and then break it down and discover by its use an alternative. If we take socket outlets for instance one reason why a socket outlet has to be 3m from a bath or shower is because of the normal flex lengths of appliances, if we use this 3m rule in a kitchen for example we could theoretically install our sockets far enough away from a door for example so that the socket can not be used outdoors, (if you follow me so far).

Other sockets could in the same way be designated and labelled , a deviation or departure could then be placed on the EIC giving a detail of this. The regulations as they stand would allow this. I think some people are of the opinion that I would condone such instances, I do not, what my intention has been all along is for us to think of alternatives, so that the next time anyone did a minor replacement or works to any circuit, the client would not be expected to upgrade the whole installation to provide all circuits with RCD protection.

I personally have found the excersise very informative, interpretation of any given regulation is always subject to individuals.

As I have said in above posts there is no wrong answer to any question, and I would not for one minute advocate the exclusion of RCD protection.

 

[monkey5]

as for testing the RCD with the test button, i always try to expain the importance of pressing it but most of the time they nod there head and you can tell there never going to do it as it means re setting the cooker/microwave/clock radio clocks! so i always finish by saying "when you change the clock forward/backwards by an hour it'll be worth pressing it then too". nearly everytime i get the reply thats a good idea. so hopefully even if its pressed only twice a year thats got to better than never aint it.

 

[spinlondon]

With regards to the boxes for departures from the Regulations.

This is to be used where a departure is intended by the designer, and not for instance a defect discovered during inspection and testing.

The departure must offer the same degree of safety as that as would be obtained by compliance with BS7671.

Would placing a socket-outlet 3m from an outside door offer the same degree of safety as would be provided by the use of an RCD?

 

[Andy™]

another thought for non-RCDing sockets - feed each socket (single sockets only) from a 230:230 isolating transformer, and marked to feed one appliance only

plenty places already do this (well, from a transformer plugged into a socket, then to equipment being tested etc)

 

[Manator]

BS7671 requires circuits of special locations to be RCD protected. There is no exception for ELV.The term used is circuits 'of' special locations, not circuits 'in' special locations.

So yes I am saying that 12V lighting would need an RCD, in order to comply with BS7671.

Is it that black and white ? Could you under the regulations install a 12v lighting circuit that would still tick all the boxes?

Very interesting however if I did do this sort of design I could justify my install and be fully comliant, that is all I have ever intended to say. The regulations at no time say I can not do this.

---------- Post Auto-Merged at 14:11 ---------- Previous post was made at 14:09 ----------

With regards to the boxes for departures from the Regulations.This is to be used where a departure is intended by the designer, and not for instance a defect discovered during inspection and testing.

The departure must offer the same degree of safety as that as would be obtained by compliance with BS7671.

Is this the penny dropping ! You have just justified the whole argument.

 

[Ali]

Monkey5, that's a brilliant idea. I'm sure that none of the people I've explained about RCD testing to have ever done it.

Can I steal your wording please? :x It would mean that RCDs get tested twice a year rather than never.

 

[spinlondon]

Is it that black and white ? Could you under the regulations install a 12v lighting circuit that would still tick all the boxes?Very interesting however if I did do this sort of design I could justify my install and be fully comliant, that is all I have ever intended to say. The regulations at no time say I can not do this.

---------- Post Auto-Merged at 14:11 ---------- Previous post was made at 14:09 ----------

Is this the penny dropping ! You have just justified the whole argument.

Yes it is that black and white.

The only way you could use 12V circuitry in a special location and not provide RCD protection, would be as a departure.

No it's not just dropped, I am well aware of the requirements of Regulations 120.3 and 120.4.

In fact one of my very first discussions on this forum was relating to departures.

However you indicated in your initial post that the installation should comply with the current Regulations.

A departure clearly does not comply with the current Regulations otherwise there would be no need to require the departure to offer the same degree of safety as would be obtained by compliance with the Regulations.

 

[sellers]

SELV is deffinatley more fail safe than an RCD.

 

[spinlondon]

So does anyone think a properly designed SELV lighting circuit (with no rcd) for a special location is safer or not than a standard RCD'd lighting circuit ?

You would have to note such as a departure on the EIC, and you would be expected to be able to guarantee and confirm that it is as safe.

 

[Andy™]

are you really trying to argue that SELV is not as safe as an RCD'd lighting circuit

 

[PC Electrics]

So does anyone think a properly designed SELV lighting circuit (with no rcd) for a special location is safer or not than a standard RCD'd lighting circuit ?

I agree that an (S)ELV lighting set up is safer than an LV lighting with additional protection by 30mA RCD.

Both are safe, however there is a marginal risk of failure of the RCD device which could result in a fatal shock, whereas a fatal shock cannot occur with ELV.

You would have to note such as a departure on the EIC, and you would be expected to be able to guarantee and confirm that it is as safe.

Please can you illucidate. I really don't understand why an ELV lighting set up would be a departure. On the contrary ELV lighting in a special location is a legitimate alternative to LV with RCD (an RCD may still be required on the LV side of an ELV set up if the LV cables are buried direct). The ELV itself does not require RCD protection - see NDQ21, 22 and 24 here to support this view:

17th Edition Guidance | New or Rewired Domestic and Similar Installations

 

[sellers]

An RCD is pretty useless on a SELV circuit.

When I say SELV i mean a proper selv circuit not an LV circuit with SELV lighting points.

 

[PC Electrics]

I take your point Sell, but either method is legitimate. Which ever way it's done there'll always be an LV side (which may require RCD protection) since the ELV circuit cannot be too long due to volt drop considerations and fittings generally can't take large csa cables.

 

[steptoe]

I think, and this is only my opinion mind, is that

YES

a normal domestic house CAN be wired without RCD protection,

is it practical,

NO,

IMHO.

so the answer to the OP question is

YES , it can be done,

BTW,

I voted no

:Blushing

:coat