I have been presented an EICR with a code 2 referencing Regulation 411.3.3, no 30mA RCD protection for socket outlets under 32amp. The 32a socket has a 100mA Time Delay RCD fitted, as it's being used to supply a local DB within a cabin. My initial thoughts were this was satisfactory and shouldn't have been coded a C2 due to the requirement for discrimination between the RCD's to avoid nuisance tripping, now I am not so sure.
C2 is the guidance from Electrical Safety First's BPG4: https://www.electricalsafetyfirst.org.uk/media/2149/bpg4-1.pdf
See page 16, 4th item down.
Why was the 32-amp socket installed and why is it being used to supply the cabin, instead of the cabin supply being hard wired?
What type of premises is it installed at and how are the premises and the cabin used?
Good question, but if it was designed as a mobile & Transportable unit ... a number have a BS EN IEC 60309 series appliance inlet fitted to them.
I might be misreading it but it seems to say an RCD can be ommitted with a documented risk assessment in this sort of situation.
Not according to Regulation 411.3.3, this is item (iii) usage, and the risk assessment exception applies only to (ii).
Perhaps if those trotting out code 2’s were asked to fully explain the potential danger, there would be less of them issued. Blind code hugging must be a significant burden to British industry!
Yes, although if it's a metal-framed or container-type mobile/transportable unit, I wouldn't be happy without RCD protection, given the risks of rodent damage. That said, as aligarjon pointed out, would a different selection of cable/connection type be more appropriate, particularly if the cabin is going to be there long-term ... especially considering this case: www.independent.co.uk/.../turney-sue-logan-fire-calder-vale-b2843032.html
Chris Pearson might be able to comment from a better position of understanding
Yes and no. I shall explain later.
I suspect the judge has erred in his assessment of what knowledge can be expected of the general public but I don't know whether that error would affect the outcome of the case - the fact (as decided by the judge) remains that the extension lead burnt down the neighbour's house.
He appears not even to have considered the standard of care of an ordinary person. The Defendant may well have thought that provided both the plug and socket were kept dry indoors, all would be well. That appears to have been the case for 13 years.
I suspect that there might be quite a few people who have a freezer in a shed fed by an extension lead, but only use it for say, a fortnight during the Christmas period. Temporary, but not immune to rodent damage.
I am surprised that there was no electrical expert involved.
- Burden of proof is the 'balance of probabilities' rather than the more onerous 'beyond reasonable doubt' required for a criminal case; and
- The principle of Occam's razor (basically, the simplest explanation is most likely to be true) being applied to competing hypotheses.
This is more complex than it may seem and I have learned something today by reading the cases.
The judge in Smith v Logan refers to appropriate authorities and although he correctly directs himself about the law, I am not sure that he applied it in reality.
Take Occam's razor first. The leading case is Rhesa Shipping Company S.A. v Edmunds (Popi M) in the House of Lords. It concerned the cause of the loss of a ship and as in our case, most of the evidence was lost (at the bottom of the sea).
Their Lordships cite with disapproval Sherlock Holmeswords to Dr Watson in The Sign of Four: "How often have I said to you that, when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"
So, Occam might lead you to the most likely cause, but that is insufficient.
The 'truth' may be that we just do not know because there is insufficient evidence, i.e. we do not know with a probability of at least 51%. Even if there are only two competing causes, the more likely one does not automatically achieve a probability of 51%.
The burden of proof rests with the Claimant on the balance of probability, and if the claimant has insufficient evidence, it may not be possible to reach that standard.
In summary, it is a two-stage process: first, identify the most likely cause; second, determine whether it is more likely than not. So, the probability of smoking being the cause might have been 10%, and rodent damage 40%, but the Claimant still loses having failed to discharge the burden of proof. I think that in the absence of any physical evidence either way, the cause must remain unknown.
ETA: I like Occam's razor - it is one of my favourite tools.
Occam's razor - it is one of my favourite tools.
Never heard of it before, but it is, in essence, the first principle of fault diagnosis in electrical installation work. Ask any spark, they may well know it simply as common sense.
I haven’t read the link yet but as far as I see it, something plugged in becomes part of the installation. At least that is my interpretation of the definition in 7671.
Thank you Chris Pearson
I am surprised that there was no electrical expert involved.
Has that also happened in other cases, and not just in the UK? I'd be interested to hear views on this one: www.rte.ie/.../
the fact (as decided by the judge) remains that the extension lead burnt down the neighbour's house.
Even that is uncertain.
Let's have a think about the electrical aspects of Smith v Logan. Paragraph numbers in parentheses.
There is no indication that overload was considered.
Electricians had visited the premises twice during the relevant period. On the first occasion something had tripped and the sparks found rodent damage to a cable under the floorboards (49). This appears to have been used to strengthen the argument that rodent damage was the cause - if it had happened once, why not again? (93) What is not explained is why the first rodent attack had not also started a fire.
Quite reasonably, the electricians were held to have no duty of care to warn the householders about the cable, but what if they had been asked? "It is obvious that if they had called in or asked a qualified electrician for advice on that point they would have been alerted to the safety requirements of the Building Regulations ..." (119). That is very speculative and it is quite possible that an electrician would have said that it was nothing to do with Part P, or BS 7671 for that matter.
The second sparks was "employed to provide additional wiring and sockets" when the kitchen was upgraded (49). Presumably the extension lead was in use at the time. Was it unplugged when ring final continuity and IR were checked? Granted the thermostat might have been open, but would it not have closed after the circuit had been isolated for a period?
The experts were agreed that "A suitable supply, installed by a competent electrician in accordance with the relevant wiring regulations, would have utilised a cable that was afforded protection against the environmental conductions to which it could be exposed, including the effects of UV radiation from the sun, and the activities of fauna." (84) I am not sure that external influence AL2 (BS 7671 Appendix 5) applies. Were the small animals present in a harmful quantity or particularly aggressive?
Above all, if any cable used where rodents might be present has to be armoured, ordinary T&E cannot be used under floorboards, in loft spaces, or other building voids.
My last question is whether rodent damage to a cable could start a fire, and would additional protection make a difference? Google seems to show that the cottages do not have an aerial supply, so let's assume TN. The judge gets a bit muddled with terminology (56) so it is unclear what had tripped: was it an MCB, or the RCD protecting a split-load board?
I think that Mr Logan's attempts to identify and isolate the faulty appliance were perfectly reasonable (56), but I am unclear as to why "each time that occurred [closing the tripped breaker] that process could have resulted in a new ignition event" (83). Having found that the fire had started when the telly went off at 18:30 (56), but was not discovered until 19:00 (57), how is this relevant? If the "new ignition events" were relevant, it undermines the hypothesis that cable damage occurred before the fire (88).
All very muddled, but thank you, Graham, for drawing our attention to the case.
A thought that I had while reading all the useful comments::
Is this not very similar to the idea of AI hallucinations?
That is, the judge is asked to determine which side was liable for damages. God was not an option.
AI has the same "must find an answer" problem and there we are currently calling them hallucinations.
Here we are a little more circumspect (cf 'muddled'), as 'the law is the law', the science has little to do with it.. 
.
I would guess the charger was faulty here possibly with lack of (RCD) Residual Current Device,though I'm not sure if even a type A would respond after a full wave rectification,2 amp current is also mentioned I'm wondering if that mixed from the maybe 5 volt 2 amp output. This almost certainly did not kill.perhaps pipework should be intentionally made to be isolated from earth.i have always though that compared to the Faraday cage principle we all used to do (equipotential bonding)
I'd be interested to hear views on this one: www.rte.ie/.../
I'm puzzled as to the shock mechanism ... are the outputs from these chargers usually referenced to Earth? (I understand they're not SELV/PELV as such these days, but to a similar but different standard). There seems to be a suggestion that contact with an earthed part completed the circuit.
How did the burn marks appear - 2A & 5V would only be 10W - thinking of my 18W soldering iron, it would take a considerable time to burn skin even if the current was concentrated over a small area (and small contact areas would seem to suggest higher resistances so lower currents). My experiences with a 9V battery and a wet tongue suggest pain but no burning or death. I'm wondering if there's more at play than just the 5V/2A output of the charger.
- Andy.
I'd be interested to hear views on this one: www.rte.ie/.../
I'm puzzled as to the shock mechanism ... are the outputs from these chargers usually referenced to Earth? (I understand they're not SELV/PELV as such these days, but to a similar but different standard). There seems to be a suggestion that contact with an earthed part completed the circuit.
How did the burn marks appear - 2A & 5V would only be 10W - thinking of my 18W soldering iron, it would take a considerable time to burn skin even if the current was concentrated over a small area (and small contact areas would seem to suggest higher resistances so lower currents). My experiences with a 9V battery and a wet tongue suggest pain but no burning or death. I'm wondering if there's more at play than just the 5V/2A output of the charger.
- Andy.
I agree that the circuit is not obvious and I'd be feeling the widower's collar.
"State Pathologist Heidi Okkers, who carried out a post-mortem examination on Ms O’Gorman’s body, said she had electrocution-type burns to her chest and left arm as well as full thickness burns to her right index finger and thumb."
Not quite sure what "electrocution-type burns" look like, but it is not unusual to see redness after using a defibrillator, which presumably, the paramedics would have used.
thinking of my 18W soldering iron, it would take a considerable time to burn skin
Not when you pick it up by the wrong end! However, I agree that the full-thickness burns suggest significant current for a significant amount of time and it implies that she could not let go. Finger and thumb strongly suggests a pinch grip, which is typical when using a modern phone.
"Consultant forensic engineer Paul Collins who examined the scene at the request of gardaí, told the inquest that the cable was just long enough to allow a phone to be held by someone in the bath with their left hand."
So why were there no burns on the left hand?
"At that point, he noticed her mobile phone and a cable in the bath, which he grabbed and threw in a sink." "Mr O'Gorman said he got a small electric shock as he was lifting his wife out of the bath before calling to his eldest daughter to dial the emergency services."
How could he have had a belt if he had already removed the putative source of the shock?
Very fishy!
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