Old Style wired fuse box

[JohnW2]

The troule with that is if something goes wrong the manufacturer has every right to say 'Not installed to our specification' and deny responsibility.

They can say what they like but, if one is prepared to engage them, it can only have effect if it is sensible. I can think of countless things that could go wrong with an appliance/whatever (e.g. due to mechanical engineering defects) that no manufacturer could sensibly argue was anything to do with the absence of RCD protection!

In any event, we were talking about EICRs, and even if something which is compliant with BS7671 is 'non-compliant with the MIs', I don't think that should be mentioned, let alone 'coded', on an EICR!

Regardless of BS7671 MI's are there for a reason, right or wrong.

"A reason", yes, but that reason is seemingly often an attempt to allow a manufacturer to wriggle out of warranty claims (or other issues of 'responsibility') in relation to things for which they clearly should accept responsibility.

Kind Regards, John

 

[SUNRAY]

They can say what they like but, if one is prepared to engage them, it can only have effect if it is sensible. I can think of countless things that could go wrong with an appliance/whatever (e.g. due to mechanical engineering defects) that no manufacturer could sensibly argue was anything to do with the absence of RCD protection!

Not the cause, but the effect is a different thing, lack of RCD will not stop the fault occuring however lack of RCD when the fault has occurred could kill someone. Such a death could not possibly be the responsibilty of the manufacturer if their MI had not been complied with.

In any event, we were talking about EICRs, and even if something which is compliant with BS7671 is 'non-compliant with the MIs', I don't think that should be mentioned, let alone 'coded', on an EICR!

Chances are the Inspector wouldn't know the MI in that situation so would not be able to code for that reason.

"A reason", yes, but that reason is seemingly often an attempt to allow a manufacturer to wriggle out of warranty claims (or other issues of 'responsibility') in relation to things for which they clearly should accept responsibility.

Kind Regards, John

I can think of situations where manufactured items require external OCD as they are intended to be components in a system etc. Can the manufacturer be held responsible for over current damage to their kit if their instructions are not complied with?

 

[JohnW2]

Not the cause, but the effect is a different thing, lack of RCD will not stop the fault occuring however lack of RCD when the fault has occurred could kill someone. Such a death could not possibly be the responsibilty of the manufacturer if their MI had not been complied with.

I think you are probably somewhat scraping the barrel to produce arguments why MIs should always be complied with.

If a design or manufacturing fault results in a (potentially fatal, even with RCD protection) electric shock. then the manufacturer clear has a lot of 'responsibility'. An RCD cannot prevent such a shock, but an RCD may (but is not guaranteed to) prevent serious injury or death resulting. I suppose that when serious injury or death has occurred, a manufacturer could attempt to mitigate their 'liability' (but not responsibility) by arguing that the electric shock caused by their product (which an RCD could not have prevented) may not have resulted in the serious injury or death.

Chances are the Inspector wouldn't know the MI in that situation so would not be able to code for that reason.

Quite - and, as I said, the discussion was about EICR coding - so, even if it were appropriate to code it (despite there being no non-compliance with BS7671) (which I doubt), it is very unlikley to be picked up by an inspector).

I can think of situations where manufactured items require external OCD as they are intended to be components in a system etc. Can the manufacturer be held responsible for over current damage to their kit if their instructions are not complied with?

'Components in a system' may, in some cases, be a different issue - but as is often said in relation to domestic appliances/equip[ment etc., if such a product requires such over-current protection, then it should be supplied internally.

However, I think you're missing the point. I don't doubt that there are probably some cases in which a 'requirement' in MIs is reasonable and justified, but many our there for far less 'honourable' reasons. That is seen at it's worst in relation to warranty claims - you surely can't sympathise with a manufacturer who attempts to wriggle out of a claim for a faulty product on the basis that, for some reason, the moulded plug had been cut off and replaced by a new plug (with the same size fuse), can you?

Kind Regards, John

 

[SUNRAY]

I think you are probably somewhat scraping the barrel to produce arguments why MIs should always be complied with.

If a design or manufacturing fault results in a (potentially fatal, even with RCD protection) electric shock. then the manufacturer clear has a lot of 'responsibility'. An RCD cannot prevent such a shock, but an RCD may (but is not guaranteed to) prevent serious injury or death resulting. I suppose that when serious injury or death has occurred, a manufacturer could attempt to mitigate their 'liability' (but not responsibility) by arguing that the electric shock caused by their product (which an RCD could not have prevented) may not have resulted in the serious injury or death.
Quite - and, as I said, the discussion was about EICR coding - so, even if it were appropriate to code it (despite there being no non-compliance with BS7671) (which I doubt), it is very unlikley to be picked up by an inspector).
'Components in a system' may, in some cases, be a different issue - but as is often said in relation to domestic appliances/equip[ment etc., if such a product requires such over-current protection, then it should be supplied internally.

However, I think you're missing the point. I don't doubt that there are probably some cases in which a 'requirement' in MIs is reasonable and justified, but many our there for far less 'honourable' reasons. That is seen at it's worst in relation to warranty claims - you surely can't sympathise with a manufacturer who attempts to wriggle out of a claim for a faulty product on the basis that, for some reason, the moulded plug had been cut off and replaced by a new plug (with the same size fuse), can you?

Kind Regards, John

I'm far from scraping the barrel. Just indicating that generally MI's are there for a reason. I agree some of them seem very wrong, the classic examples being changing the plug and winnies 16A FCU.
I freely admit that some of my work has resulted in installations contrary to MI's so I fully understand your (and others) comments. Additionally also modified new kit so totally destroying original warranty in some cases.

I'm thinking in terms of components in systems for example heating where a valve has a 2 or 3A end switch, would you really advocate having a fuse for every contact? What a faultfinding nighmare.

I'm not silly enough to make the statement that faults can't arise, or if they do, that any/all faults are the manufacturers liability/responsibility. If you are do you put some sort of time limit on it or leave it open ended?

 

[JohnW2]

I'm far from scraping the barrel. Just indicating that generally MI's are there for a reason.

... and I've agreed with that, but adding that "the reason" is seemingly often in relation to the interests of the manufacturer, not customers/consumers/users/whoever.

I agree some of them seem very wrong, the classic examples being changing the plug and winnies 16A FCU.

Indeed, but factually 'wrong' (as in the 16A FCU) is probably pretty rare. The thing I personally believe to be 'wrong' is that they often seem to be specifying 'requirements' (with 'MUST' quite often with capital letters) in situations when I think they would more appropriately be issuing 'recommendations'.

I freely admit that some of my work has resulted in installations contrary to MI's so I fully understand your (and others) comments. Additionally also modified new kit so totally destroying original warranty in some cases.

I'm sure that most of us have been known to do both those things - not the least, in my case, every time I install something that the MIs say "MUST be installed by a qualified electrician" (whatever a "qualified electrician" may be {but I'm certainly not one of them}!)

I'm thinking in terms of components in systems for example heating where a valve has a 2 or 3A end switch, would you really advocate having a fuse for every contact? What a faultfinding nighmare.

I conceded that things might be different in relation to "components in systems". However, in cases such as you cite, I think I would probably be questioning whether such a "2A or 3A end switch" really requires any over-current protection at all (internal or external), beyond what is required to protect the supply cables.

Kind Regards, John

 

[SUNRAY]

I conceded that things might be different in relation to "components in systems". However, in cases such as you cite, I think I would probably be questioning whether such a "2A or 3A end switch" really requires any over-current protection at all (internal or external), beyond what is required to protect the supply cables.
Kind Regards, John

Ah yes but the problem arises when the system grows and 3A fuse is not enough to run several pumps and isolating sections for different fuses is impractical due to the interaction (been there got the t-shirts).

Then we read winnies comments advocating such systems being installed as done abroad on 16A OCD's without any problems. Which of course it within our regs (possibly not the latest due to Brexit) to install to member states regs.

 

[JohnW2]

Ah yes but the problem arises when the system grows and 3A fuse is not enough to run several pumps and isolating sections for different fuses is impractical due to the interaction (been there got the t-shirts).

I think you may be talking yourself into a corner!

If one has individual components within a system which, for some reason, really do need over-current protection tighter than that covering the entire system, then one presumably has no choice but to provide individual protection for each such components (or groups of such items), within or external to the component(s) - unless you can think of some other approach.

However, as I said, it's the question of whether individual components often "really do need" over-current protection that I would be asking.

I think that people tend to have too much 'faith' in protective devices. Despite what many people seem to think/feel, consciously or subconsciously, devices such as fuses, MCBs and RCDs do not 'limit' the magnitude of anything (an over-current, or current through a person getting a shock). All they can do is to limit the duration of the current, and no device is anything like 'infinitely fast', so the current in question will flow for a finite time before the circuit is de-energised. In the case of damage due to over-current (most commonly a very high 'fault' current), things like switches and semiconductors will be damaged, usually irrevocably, almost 'instantly' - hence before any real-world OPD is likely to prevent it.

Then we read winnies comments advocating such systems being installed as done abroad on 16A OCD's without any problems. Which of course it within our regs (possibly not the latest due to Brexit) to install to member states regs.

Particularly when we were in the EU, we were always hearing this from eric, but I don't know where in BS7671 it comes from. There is, of course, no compulsion in the UK to comply with BS7671 at all (provided one can in some other way sucessfully argue that Part P is satisfied), but I don't know where this business about other country's regs (be they in the EU or not) comes from!

Kind Regards, John

 

[ericmark]

My thoughts are, I know in the past I have made errors, and I have not foreseen a scenario which could cause danger. Be it manufactures, BSi, or IET I can't claim to be better at seeing danger.

So if a manufactures, BSi, or IET for example says it should be fitted with a type B RCD 30 mA and 100 amp the question is have I got enough skill to say they are wrong?

Also how much danger is going to result in not following their recommendations?

So in my own home, I made an error, I looked at the packets with the RCBO's in saw type B written on the packet, and thought that's better than I expected, only expecting type A, curve B. It transpired after they had been fitted they were type AC curve B, and I had inverter washing machine, freezer, and fridge freezer, I order type A to replace them but colvid19 resulted in a short supply, so I made the executive decision that type AC is likely good enough, I have made a risk assessment and decided the likely hood of both a earth leakage fault and a dc current freezing the RCBO at the same time is very unlikely. This is all well and good in my own home, but can I do the same with some one else's home?

And this is the problem, if some one says it needs a thingamajig, what ever it is, can I as the inspector say they are wrong?

To my mind the answer is pass the buck, I code it as C3 and then up to owner if he does an upgrade, but is this the right attitude, should I air on the safe side and say C2?

As yet not seen a single C2 for having wrong type of RCD, and unless a TT supply the RCD is secondary protection, so even if my RCBO is frozen a fault should still trip the over current part of the RCBO. So I feel with 14 RCBO's I am safe, but what when only two RCD's? Personally I still feel no really requirement for any RCD protection with a TN supply. But what about a TT supply?

In the past a 100 mA or even 300 mA trip was thought enough, and if it will trip with 300 mA then likely good enough, but what if there is DC? Again 14 RCBO's it seems unlikely multi faults could stop them tripping, but what about a single RCD?

The point is as some one who has trained to level 5 I can't answer the question, and the C&G 2391 is only level 3, so is it fair to ask an inspector to make that judgement, I would say no, he has to look to his peers, be it the electrical safety council or some one else, so I can't say if a code C2 or a code C3 is right or wrong, and for any law to say C2 is a fail and C3 is a pass is crazy.

 

[JohnW2]

... for any law to say C2 is a fail and C3 is a pass is crazy.

I don't think there is anything crazy about a law saying that anything which is considered to pose a "potential danger" is a fail, and something not considered to pose a "potential danger" is a pass, is there?

The problem is that there is no officially-prescribed, hence no consistent, way of deciding whether something IS considered to "pose a potential danger". so it's just down to the judgment of individual inspectors - which I don't think is a very satisfactory situation.

Kind Regards, John

 

[SUNRAY]

I think you may be talking yourself into a corner!

If one has individual components within a system which, for some reason, really do need over-current protection tighter than that covering the entire system, then one presumably has no choice but to provide individual protection for each such components (or groups of such items), within or external to the component(s) - unless you can think of some other approach.

However, as I said, it's the question of whether individual components often "really do need" over-current protection that I would be asking.

I think that people tend to have too much 'faith' in protective devices. Despite what many people seem to think/feel, consciously or subconsciously, devices such as fuses, MCBs and RCDs do not 'limit' the magnitude of anything (an over-current, or current through a person getting a shock). All they can do is to limit the duration of the current, and no device is anything like 'infinitely fast', so the current in question will flow for a finite time before the circuit is de-energised. In the case of damage due to over-current (most commonly a very high 'fault' current), things like switches and semiconductors will be damaged, usually irrevocably, almost 'instantly' - hence before any real-world OPD is likely to prevent it.
Particularly when we were in the EU, we were always hearing this from eric, but I don't know where in BS7671 it comes from. There is, of course, no compulsion in the UK to comply with BS7671 at all (provided one can in some other way sucessfully argue that Part P is satisfied), but I don't know where this business about other country's regs (be they in the EU or not) comes from!

Kind Regards, John

Definitely no corner, my difficulty is trying to explain a situation. As a controls person this is something I regularly encounter, the big problem is the number of 'common conexions' in a circuit, ie the number of things hanging on a single contact (which commonly have 0.5mm² flexes) somewhere in the system as it grows, additionally there may be several contacts in parrallel of which any or several may be carrying that current. The solution is to include relays so the sensors and end switches etc are only taking control currents and not power. I'm not thinking about fault current of many amps just overloads where I'd hope a fuse (or in a control panel more commonly MCB) would do its job

 

[JohnW2]

Definitely no corner, my difficulty is trying to explain a situation. As a controls person this is something I regularly encounter, the big problem is the number of 'common conexions' in a circuit, ie the number of things hanging on a single contact (which commonly have 0.5mm² flexes) somewhere in the system as it grows, additionally there may be several contacts in parrallel of which any or several may be carrying that current. The solution is to include relays so the sensors and end switches etc are only taking control currents and not power. I'm not thinking about fault current of many amps just overloads where I'd hope a fuse (or in a control panel more commonly MCB) would do its job

I know that we are all very guilty of 'drifting threads', but you seem to have drifted this one onto something totally unrelated. To remind you, this all started when I reminded eric ...

.... The 18th ed. of BS7671 requires only that one should 'take account of' manufacturer's instructions. If one has a convincing argument as to why an RCD is not required (whilst maintaining compliance with BS7671), then one can 'ignore' any 'requirement' specified in the MIs.

... and you responded by saying that requirements in MIs were "there for a reason". How did we get from there to what you are now writing about? ... and what is the relevance of the latter to the former?

Kind Regards, John

 

[SUNRAY]

I know that we are all very guilty of 'drifting threads', but you seem to have drifted this one onto something totally unrelated. To remind you, this all started when I reminded eric ...
... and you responded by saying that requirements in MIs were "there for a reason". How did we get from there to what you are now writing about? ... and what is the relevance of the latter to the former?

Kind Regards, John

Basically most of my posts in this thread are a response to your questions and statements. IMO it started veering off course in posts #11 & particularly the response in #12

The 18th ed. of BS7671 requires only that one should 'take account of' manufacturer's instructions. If one has a convincing argument as to why an RCD is not required (whilst maintaining compliance with BS7671), then one can 'ignore' any 'reuirement' specified in the MIs.

Kind Regards, John

Until then all I'd posted was:

Don't worry about what the rules/law says.

Just get a sparks in, get them to replace it to do your best to protect your tenant and do the EICR at the same time.

 

[JohnW2]

Basically most of my posts in this thread are a response to your questions and statements. IMO it started veering off course in posts #11 & particularly the response in #12 ... Until then all I'd posted was:

As I said,it appeared to happen when you responded, in post #15, to what I wrote to eric in #12 (reminding him that BS7671 no long requires 'blind adherence' to MIs).

Anyway, that's all history, but I don't think that the 'drift' has been helping the primary discussion (or OP)

Kind Regards, John