RCD socket outlet.

415.1.2


Z.

I did look at the IET Guidance Note and Graham is acknowledged for his contributions on page 6, So has a far more detailed knowledge of its contents than the rest of us.


In the GN it actually says:

13.2.1

The effect of applying main protective bonding is most noticeable in TT systems.


Going back to the discussion, a RCD won’t protect you from faults upstream of it, so the earthing and bonding needs to be sound to reduce touch voltages downstream of the RCD from faults up or down stream of it.


You don’t want anyone to die in the bathroom because there is a faulty electric heater in a bedroom, has as happened.


 Andy Betteridge 

I find bonding extraneous-conductive-parts and exposed-conductive-parts very satisfying in locations like bathrooms or shower rooms etc. It is a kind of passive, reliable,  bullet proof protection method, until meddled with by others such as D.I.Y.ers or plumbers. It has no moving parts, and is normally quietly active and on guard 24/7. It is to be recommended.


Z.

In the GN it actually says:

13.2.1

The effect of applying main protective bonding is most noticeable in TT systems

or to put it another way, in some circumstances with a L-PE fault internal to the installation, main bonding in a TN system provides little more reliable benefit than a chocolate tea pot.


  -  Andy.

We made that transition from EEBADS- Earthed Equipotential Bonding and Automatic Disconnection of Supply to ADS- Automatic Disconnection of Supply.


The house that Dave is asking about was presumably installed as EEBADS without any RCD protection in the consumer unit or fuse board at all, indeed it is still possible to install some circuits in homes without RCD protection, though not lighting circuits anymore as they require RCD protection as of this year.


So it is more than feasible that you could be called to a house where people are getting electric shocks off the kitchen tap, because someone messed up replacing a light fitting on a  non-RCD protected light circuit and the requirements for EEBADS was not fulfilled or has been compromised.At the very least an electrician can be expected to do an earth fault loop test when replacing a light fitting and anyone else should confirm earth continuity in some other very basic way. It could happen the other way around, someone could replace a light fitting then get shocks off it due to an existing fault elsewhere.


So replacing a light fitting or anything similar still requires some basic inspection and testing; and yes the closer the a RCD that may be installed is to the electric suppliers intake, and the more circuits it protects, the safer the installation will be and putting the RCD at the end of the circuit is the least favorable choice.


I have walked away from jobs like the one Dave asked about after the customer declined to have main protective bonding conductors installed along with a new consumer unit, at one house the customer said I don't want those I will just have the extra socket. Someone else wanted some new sockets installed in a TT installation protected by an ELCB that had had its earth rod removed, when i mentioned having to have a new consumer unit and earthing installed she got all uppity with me and said she had just had her kitchen rewired by the kitchen fitters and they had not said there was anything wrong with it and she wasn't going to pay for anything other than the new sockets she wanted in the bedrooms for her lodgers to use. Installing SRCDs in either of those homes would not have resolved the fundamental problems.


You have to know when it's time to walk away, if an installation was not safe thirty years ago just bunging in random RCDs is not going to make it safe now.


There is a time and a place for installing SRCDs and FCRCDs subject to other criteria being met, but those who wrote the British Standard for them don't appear to identified when and where that is.


Andy Betteridge.

Sparkingchip:

The house that Dave is asking about was presumably installed as EEBADS without any RCD protection in the consumer unit or fuse board at all, indeed it is still possible to install some circuits in homes without RCD protection, though not lighting circuits anymore as they require RCD protection as of this year.

Andy makes a good point. RCD is not the cure for everything. Despite JP's remonstrations, I am happy with my 15th Edn installation. However, I do acknowledge that it does not provide protection from, for example, that frayed cable on Mrs P's iron that she has not mentioned. ??

It seems to me that the reason this subject is so topical now is because the old BS7288 has only just ceased to be current.

BS7288 2016 says, 'SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.' 

BS7288 1990 has only just ceased to be current (30 Nov 2019)

BS7671 has never listed BS7288 as being suitable additional protection.

BS7288 products have improved their testing standards but still do not match the standard applied to BSEN 61008.

Quite why it has taken 30 years to have the blinkers removed on this subject, despite questions through the ages, is beyond me.

A big shout out to John Peckham for his valuable insights.


Having said that, I wouldn't want to see a decline in use of SRCD's.