AC Type RCD No PV or Car Charger C3 or C2

Yesterday's announcement from the Government: https://www.gov.uk/government/news/government-to-go-further-and-faster-in-becoming-energy-secure

If plug-in PV is being pushed as a way forward, and these are to have a UK standard plug (although BS 1363-1:2023 Clause 5 states that the UK plug shall not be used for connecting generators) then certainly in rented homes, and in flats (rented or otherwise), for the installation to be considered safe, surely:

1. RCDs (RCCBs and RCBOs) for socket-outlet circuits (and upstream distribution circuits if applicable) would have to be at least Type A (because of the way inverters operate, but also for the existing PV inverter standard BS EN 62109-1, this is stated as a requirement for 'pluggable type A' equipment (i.e.. with a standard plug) to be compatible with Type A RCDs; and

2. RCDs (RCCBs and RCBOs) for socket-outlet circuits (and upstream distribution circuits if applicable) would have to be bidirectional (Regulation 530.3.201 introduced in Amendment 3); and

3. RCDs (RCCBs and RCBOs) for socket-outlet circuits would have to disconnect all live conductors (see Regulation 551.7.1)?

And anecdotally if not saved , certainly less badly burnt. 
I for example have been disconnected by 30mA RCD, just once ,and was very grateful for it, but still painfully shaken. I have also been saved by the prompt action of a colleague, on something that had no RCDs, but that left my hands with lovely entry and exit wounds that took weeks to heal. Both were very close calls, and once (twice?) in a lifetime events that required many things to have gone wrong so unlikely, and that is for one who gets stuck in more than the average member of the public.
Equally there must be millions of RCDs that are never called upon to trip in anger during their whole operational life (and of those that are, as above a small % wont..)
If we assume my life is worth £1Million (!) then that justifies the cost of fitting about  50K RCDs at say £20 each on new circuits to save me once.
To call someone out to do a replacement, and certainly if that involves a new CU, is probably ten times more expensive, now unless someone gets saved once per 5000 RCDs installed, it is a net loss. We have less than 100 electrocutions per year (*), which is a chance of somewhere between one and two per million, per year, per person.

As such the argument for the additional cost vs benefit on new circuits is reasonably in favour, but the argument for "must retrofit" to existing is probably rather weak.

Mike

** Actually a lot of those electrocutions are touching overhead lines with vehicles and poles, and there is no number of additional domestic RCDs that would help with that so maybe more like less than 1 per million. But there is an additional reduction in fires and so on to offset that a bit.

mapj1 said:

If we assume my life is worth £1Million (!) then that justifies the cost of fitting about  50K RCDs at say £20 each on new circuits to save me once.

It isn't quite that simple. You really need to do a number needed to treat analysis. The difficulty is that electrocution is (mercifully) rare.

Let us suppose that the death rate from electricity is 1 in a million = 10^-6 = 10 x 10^-7. We have a new gizmo, which reduces the mortality by half, so 5 x 10^-7. Absolute risk reduction is (10 x 10^-7) - (5 x 10^-7) = 5 x 10^-7. NNT = 1/ARR = 2 x 10⁶.

So 2 million new gizmos have to be fitted to save one life.

gkenyon said:

It has certainly been stated in expert evidence that RCD could have saved a life if one had been fitted.

As I stated earlier. 

Considering the time it take to write/publish a BS like BS7671 the lifecycle should start to consider the recommendation of of type B as a minimum for BS7671 Ammendment 5 or 19th edition. Ideal for EV chargers, solar PV (inverters).  Caveat could be if it a new design or retrofit

Lets not forget the type F as well for inverter driven loads like washing machines and heat pumps. 

 I am sure that will be an interesting debate for the JPEL Team for UK Domestic Dwellings

As always there is a grey area

What is recommended/mandated for a New Design

What coding is given on an EICR or In Service inspection and testing.  This could be 3,5 or even 10 years after initial install depending on usage.  If for homeowner usage it could be 10 to 20 years or untill the sell the property.  if the property is PRS (Private Rental Sector) then EIC and EICR are needed from day 1 of the rental agreement.  In effect theis makes a 2 tear system.  Rented dwellings are more upto date (BS7671) than owner/occupied dwellings.  

I am sure you family would rather pay £10 per RCBO in the CU and have you still there and very much alive.  The £1Million value is just what bank and insurance companies use to quantify a life.  Your family would say your life is worth way more than that and may even be priceless.  

gkenyon said:

It has certainly been stated in expert evidence that RCD could have saved a life if one had been fitted.

A very valid point!

Perhaps more difficult to convince a court that a type A instead of type AC would have made a difference?

Chris Pearson said:

Perhaps more difficult to convince a court that a type A instead of type AC would have made a difference?

I can see it would be difficult if the burden of proof was 'beyond reasonable doubt' ... where 'balance of probabilities' applies, it would be easier, especially if the evidence showed an RCD didn't operate when (all things being equal) you would have expected it to do so.

There is plenty of information on the internet that a type AC can/may get blinded so a type A or B or F would be a better choice.  A judge or a jourer could look it up and ask their prefered AI engine

I am sure you family would rather pay £10 per RCBO in the CU and have you still there and very much alive.

That may indeed be true or not, and they don't know it but they already have paid for some RCBOs in our home CU. However they are not going to want to pay for lots of RCDs that never get called on to do anything in properties that none of us will ever visit, especially if it takes money from other safety activities like putting winter tyres on the car or boiler checks.. And more generally is not wise to ask family members to estimate your value, as it may be less than that megapound.
Mike

Sergio Fernandez said:

I am sure you family would rather pay £10 per RCBO in the CU and have you still there and very much alive.

What a kind assumption! :-)

Whether the RCD failure rate be 3% or 7%, I'd like to know whether the more expensive brands are more reliable. By and large, I think that a free market decides the question, but I really do not know. £1k SP DBs do exist - are they worth it?

That 3% - 7% failure rate might scupper a charge of corporate manslaughter, but you would still have the difficulty of causation and foreseeability in a civil case. Only the lawyers would benefit.

That 3% - 7% failure rate might scupper a charge of corporate manslaughter, but you would still have the difficulty of causation and foreseeability in a civil case. Only the lawyers would benefit.