RCD socket outlet.

Using common sense, and implementing good design, it must always be better in a home to have 30mA R.C.D. protection than not have it, from a safety point of view, whatever form that takes.


Z.

Sparkingchip:

All 30 mA RCD devices produced to British Standards are equally effective at providing additional protection.

And should you want to debate that point, consider that the old mechanical BS4293 RCDs are quicker and operate at a lower threshold than the latest Hager Type A RCDs to BS61008.


Andy Betteridge

'Where this is the case and it is not practical to include RCD protection at the consumer unit a 13 A RCD spur maybe installed locally.'

The article is a very good but there is an omission in the text.  Every mention of standards of protection is scrupulously supported with a reference to the relevant BS7671 regulation...  exceptionally, there is no regulation given for this recommendation. What regulation should be inserted to qualify the prescribed method ?

Good morning members of the flat earth society, at least it feels that way as those people refuse to believed any evidence that is contrary to their belief.


A few points that may help some of you come to a different view.


Chris


Your SRCD near doors to the outside on your 15th Edition installation were no no doubt put there to comply with regulation 471-12 of the 15th Edition to protect leads and appliances going outside the equipotential zone. Your SRCDs would have no doubt complied with BS 7288-1990 not the current BS 7288-2016. I would recommend you bring your whole installation up to the 18th Edition standard for the added benefits. Just to show I am not smug I have a house with a 16th Edition installation. I have a new dual RCD board sitting on the floor waiting for me to get my a**e in to gear and get it fitted, in my defence I do now have Type 2 surge protection on my newly fitted REC 2 isolator carried out as part of the enabling works for the CU upgrade.


Andy B


Back to school for you. RCDs do not limit touch voltage to 50V.  Andy J pointed you in the right direction. RCDs do not limit current or voltage they limit time a set current can go for. Most of our protection is time based. The touch voltage under earth fault conditions is dependent on the ratio of R1 and R2. Also your comment on 50V and sometimes 70V being a whim of JPEL, not true. I assume you are referring to 722 which relates to hand to foot contact, not hand to hand.


You asked what law must be complied with? If it domestic installation work then the Building Regulations requires compliance with BS 7671 not just for notifiable works. The Approved Document says "should" I would have preferred "shall".


To help you get off to sleep this afternoon post a traditional British Sunday lunch I would recommend reading the following.


1. Approved Document P.

2. BS 7288-1990 and BS 7288-2016.

3. BS 7671 531.3.6 noting the word "shall".

4.BS 7671 511.1. and then a look through Appendix 1 to see if BS 7288 is there?

5. BS 7671 Regulation 133.1.3.

6. And for good measure and to see the big picture BS EN 61140-2016 "Protection against electric shock common aspects for installation and equipment, and in particular Clause 5.5.1 re. Additional Protection.


I can hear the chants now of "How the hell can I read all those standards, have you seen the price". No you don't have to, the wise old men and women on JPEL have done that for you and put the outcome in BS 7671. 


If I may ask a rude question, " Are you happy to sign EICs and Minor Works as being compliant with BS 7671 when you have fitted an SRCD"? How would you code a BS 7288-2016 having discovered one on a periodic inspection?

Andy B.

"And should you want to debate that point, consider that the old mechanical BS4293 RCDs are quicker and operate at a lower threshold than the latest Hager Type A RCDs to BS61008."

Not sure I follow you on that statement Andy. Could you elaborate a bit please.


To all.

Yes I think our  esteemed Mr Peckham is actually correct (don`t tell him though!).

I think we all thought the omission of the old RCD BS was an error but perhaps it was actually deliberate after all.

Practically we all seem to think it is a good idea to fit one rather than nothing and we must be ready to be brought to account if we do not.

That risk is probably quite tiny but is probably present nonetheless.

We all live in the real world and JP knows that but he is explaining to us the facts rather than just an opinion I think.


As a comparison. None of us ever works live and none of us ever fails to notify notifiable jobs after all do we?

Quote:


“Andy B


Back to school for you. RCDs do not limit touch voltage to 50V”


That is exactly the point I was making, you cannot connect a RCD to a circuit and installation that is not adequately earthed and bonded or else a fault elsewhere in the installation may raise the voltage of earthed equipment downstream of the RCD to dangerous levels, a RCD does not remove the requirements for basic and fault protection along with the requirement to mitigate touch voltages.


We are not even supposed to to test the RCD without doing an earth fault loop impedance test first to ensure that the circuit is adequately earthed.


The first thing you do when you arrive on site to alter or extend a circuit is to confirm the type and adequacy of the installation earthing arrangement, then you confirm if the circuit you are going to work on is fit and healthy,  so personally I walk in and visually inspect the distributors equipment, the main earth and earthing arrangement, the consumers consumer unit or fuse board, then go to the point where I want to alter or extend the circuit and do an earth loop impedance test, then if there is a RCD protecting the circuit disconnect the circuit by testing the RCD.


That process is not perfect, you may be able to see that there is a main earth conductor installed to a suppliers TN earth terminal, but in reality there could be a high resistance termination or fault rendering it useless, but you got a good loop test result due to a parallel path such as the gas pipe, that’s life.


 Andy Betteridge 

I am sat trying to do an invoice that I should have done a few weeks ago, there have been a series of very brief power outages on the local power supply that has knocked my desktop computer off at least ten times now as well as taking down the home internet connection, I’m losing the will to carry on trying to do the invoice at the moment.


Regards the installation of SRCD devices, they were only a choice of last resort when a DP RCD could not be sensibly installed.


So moving on I have actually bought a supply of Europa double pole RCBOs  and enclosures, now explain me how one of those inserted into an existing circuit affords a better level of additional protection than a DP SRCD?

The point is there are installations with earthing and bonding that were installed and considered safe, the requirement that has come in requires ADDITIONAL protection in some locations using 30 mA RCDs, that does not actually mean the original requirement has been removed, it is additional not instead of.


You cannot insert a RCD into a dangerous circuit and say that you have done a good job, it has to meet all the basic requirements.


Andy Betteridge