Private Message replies to threads.

[JohnW2]

Agreed. Unfortunately, in a domestic environment, one is often confronted by one of the lovely LABC folk. Their view is often that the house you have just wired (perhaps to Bulgarian standards) is not compliant with their “Approved Document” bible.

Sure - which is the reason why, in practice, virtually everyone uses 'compliance with BS7671' as their way of demonstrating compliance with the law (part P).

However, what you say goes a bit further than that. If I wanted to satisfy 'LABC folk' I would almost certainly use 'compliance with BS7671' as my demonstration of compliance with Part P (to avoid all the hassle of trying to do it in any other way) - but when I say 'compliance with BS7671), I mean 'compliance with BS7671', regardless of what Approved Doc P may say. If I encountered a situation in which an LABC person was attempting to 'require' (for 'compliance with Part P') something which existed in Approved Doc P but was not required by BS7671 (i..e. if what had been done was fully compliant with BS7671), then I would probably vigorously challenge that 'requirement' ... but maybe that's just me!

However, nor do I take eric's apparent view that working to some 'foreign' set of wiring regulations (be they German, Bulgarian or whatever!) necessarily automatically serves as evidence of compliance with Part P - to my mind, whether or not that is the case depends entirely on what the foreign regulations in question actually say!

Kind Regards, John

 

[Harry Bloomfield]

The rest of the room was full of assorted bits and pieces including offcuts of copper pipe, conduit, studding etc and no body else thought it may be risky.

Sounds just like a sub-station I visited in Scarborough, just a few years ago, when a phase was lost

One can always argue that 'one tragedy is one too many', and thereby attempt to justify 'preventive measures' (which may sometimes be extremely costly). However, like it or not, we have to draw line somewhere - otherwise we presumably would have no electricity at all (or, at least, no electricity >ELV), and certainly no cars.

Sometimes the preventative measure can make a situation even more dangerous. I have in mind a massive underground pumping station, in the process of being fitted up with the massive pipes and massive motors and pumps - real heavy duty engineering, for a new reservoir. Site supply was the usual 110v several Kw site transformer, fed from an early RCD and supplying all the working lights in the otherwise totally black underground, with lots of deep holes to fall down. Someone had thought it a good idea to include an early RCD in the supply to the site transformer which regularly tripped for absolutely no obvious reason, than a surge in the loading leaving everyone feeling their way around in the dark. CofW would not have it that the RCD was causing more risk, than reducing risk - site rules is rules.

So far as cars are concerned and their safety systems - I don't think I would like to go back to the days of risking being impaled by solid steering rods, no seat belts, no crumple zones and no airbags. Especially not now, with so many absolute nutters on the road, putting everyone at risk. I have always gone for the larger cars, in the hope of coming off best in an accident. My present car has one of the most rigid cabins on the road, with four airbags just for the driver.

 

[JohnW2]

Sometimes the preventative measure can make a situation even more dangerous.

Indeed - particularly given that it is, more often than not, a matter of balancing one risk against another. Continuing your RCD theme, some people seem to get very worried/'excited' about the 'potential danger' of having many/all circuits protected by the same RCD - but that risk would obviously not arise if there were no RCDs at all!

So far as cars are concerned and their safety systems - I don't think I would like to go back to the days of risking being impaled by solid steering rods, no seat belts, no crumple zones and no airbags.

Sure, we all welcome progressive technological and other advances which increase safety. However, that's not quite the point I was making - rather, I was saying that (given other considerations) there is a limit to how far the state can go in protecting people against relatively small risks (particularly when there is a practical and/or 'convenience' issue on the other side of the equation) - for example if 'they' wanted to reduce the number of road deaths to, or below, the number of deaths due to electricity, they would either have to ban road vehicles completely or else have some ridiculously draconian rules like a nationwide 10 mph speed limit!

Kind Regards, John

 

[SUNRAY]

Sounds just like a sub-station I visited in Scarborough, just a few years ago, when a phase was lost

TBH that sort of thing was not particularly rare but that was the worst I'd seen.

This was the mains intake for a manufacturer of air handling units, although it is a large open space, nearly big enough for a football pitch, the actual power requirement is quite modest. the largest items being the 15KW compressor and spot welder on 20 and 15A fuses.
Apart from the bare conductors and switches, the space between them and the mesh wall was small and certainly not wide enough for me [15-16 stone] to get past an 'off' switch

Sometimes the preventative measure can make a situation even more dangerous. .... CofW would not have it ... was causing more risk, than reducing risk - site rules is rules.

I've called HSE onto 3 building sites where I/we were instructed to do things where 'site safety' was making things hazardous to health, 2 resulted in site shut downs so I wasn't popular.

 

[Harry Bloomfield]

I've called HSE onto 3 building sites where I/we were instructed to do things where 'site safety' was making things hazardous to health, 2 resulted in site shut downs so I wasn't popular.

What a man's gota do a man's gota do. I twice closed two city centre banks down, in mid-afternoon after discovering a serious H&S issue in one and a security breach in the other, enough to cause an immediate evacuation.

 

[ericmark]

I will admit the yellow brick transformer is one of the most dangerous things on building sites, and they have caused many fires, 10 amp cut out often built into the supply so for the output 10x230/55 = 42 amp, and 1.5 mm² flex will not take that current, and so with extension plugged into extension so not enough current to open the cut out, but enough to melt cables and set wood scaffolding planks on fire. If there was RCD protection on the 110 volt supply then it would be safe, and since reduced low voltage not extra low voltage I suppose there should be RCD protection, but to date not seen a yellow brick with RCD or MCB protection on output.

A risk assessment reduced low voltage to low voltage the reduced wins, but any risk assessment does not take into account no RCD protection or incorrectly sized over loads as this should not be permitted. You can't guard against people breaking the rules.

As to closing down with safety concerns, we had tower cranes, and one dropped its load, the mechanical engineer as he should closed down all the tower cranes on site, and the Italian manufacturer was summoned to find the fault, their representative arrived and said the problem was the generators over speeding, he was recording 100 Hz, well CAT engines designed to run at 3000 RPM are taken to 6000 RPM it does them no good, and ones ears can tell you there is some thing really wrong, however it was clear the engine was not hitting that speed, the Ward Lennon drive was causing the engine speed to raise, but the cycles were no more than 60 Hz.

So my boss and I looked at each other as said together, some thing with a diode has gone faulty, and it transpired we were correct, a drive for another function was interfering with the main drive. He changed the faulty drive and all cranes started working again.

I was not happy with this, if a faulty drive can cause another drive to fail to my mind the other drive needs modifying to stop this, however I had an unrelated accident and my boss resigned as a result, so the cranes continued to work. On a mains supply there was no real problem, other items on the supply smoothed the supply and stopped it being seen as 100 Hz, the problem only arose when supplied from generators. But a 350 kVA generator is not a small beast.

 

[winston1]

If there was RCD protection on the 110 volt supply then it would be safe, and since reduced low voltage not extra low voltage I suppose there should be RCD protection, but to date not seen a yellow brick with RCD or MCB protection on output.

I thought the output of yellow bricks was floating not referenced to earth. A RCD would not work. MCB would be useful though.

 

[Harry Bloomfield]

I thought the output of yellow bricks was floating not referenced to earth. A RCD would not work. MCB would be useful though.

From memory of long ago, the yellow bricks are centre tapped to earth, so 55v to earth from either pole - but double insulated from the 240v input.

 

[Taylortwocities]

I thought the output of yellow bricks was floating not referenced to earth.

Wrong. That’s a shaver socket.

From memory of long ago, the yellow bricks are centre tapped to earth, so 55v to earth from either pole - but double insulated from the 240v input.

Correct

education

 

[SUNRAY]

I thought the output of yellow bricks was floating not referenced to earth. A RCD would not work. MCB would be useful though.

EDIT: sorry couldn't resist the temptation to highlight my reply
Yet another case of Winston not knowing what he's talking about.

 

[winston1]

EDIT: sorry couldn't resist the temptation to highlight my reply
Yet another case of Winston not knowing what he's talking about.

There is ABSOLUTELY NO NEED TO BE CHILDISH LIKE THAT. I did say I thought the output was floating. All you had to say that was not the case.

 

[JohnW2]

.... I did say I thought the output was floating. ...

You did.

However, for the sake of those who read your posts, it might be best if you restricted yourself to posting information which you at least believe to be correct (even though you are sometimes wrong in that belief), rather than things which you 'think' may be correct?

 

[SUNRAY]

There is ABSOLUTELY NO NEED TO BE CHILDISH LIKE THAT. I did say I thought the output was floating. All you had to say that was not the case.

Pettle and kot.
The number of times you have blatantly stated posts are wrong and then gone on to argue the point even when multiple posters have explained in detail where and why you're wrong.
Now YOU are silly enough to call ME childish when I mention you are wrong again?

 

[ericmark]

I have made many mistakes, and it is the way forums operate that allows people to correct me when I make an error, some times it seems pedantic, I called it a ring instead or ring final or live instead of line. However other times I have made real errors like missing a decimal point.

I have worked on an IT system, a Robin tunnel boring machine, I hope I will never need to do so again, a really shocking experience.

But even the IT initials cause problems, insulated from terrestrial is not the same as information technology, and we have a number of examples where a set of initials can cause problems, RCD being recreational craft directive or PC being the IBM registered trade make for personal computer seems it does not mean a police constable any more!

Any way to be political correct CD means core diplomat and has nothing to do with a compact disc. God knows what a CD player is?

The centre tap of the 110 system caused a load of problems on the building of T5 at Heathrow when some one imported a load of lighting sets from USA. They were wired 110 - 0 - 110 volt, so 220 volt to lights centre tapped, but also had 110 volt outputs, the Australian electrician who serviced them had no idea these did not comply with British regulations. He was employed as an auto electrician so not really his fault.

And this international language English does have a problem where in USA low voltage does not have same meaning as any where else in the world.

@winston1 errors are not unusual, we all make errors, the only problem is his inability to accept he is in error, however I can understand this, I have also been told I am in error, 3 meter rule on overload protection for example, I would accept that with a spur from a ring this rule likely should not apply, but we are really talking about English language not electrics when reading BS 7671.

What is a transformer, in English an electronic transformer is correct, electrically it may be not correct. And however much we think calling a device a bulb, transformer, driver, ballast, or MR16 is wrong, if the manufacturers use that name, we really have to just bend.

Yes I think @winston1 gets it wrong many times, but as to if he gets it wrong more than me, or any other poster not so sure.

 

[plugwash]

And this international language English does have a problem where in USA low voltage does not have same meaning as any where else in the world.

And more broadly, that in plain English low and high are relative and/or context dependent terms. What is high to a microelectronics guy is very low to a power distribution guy. The IEC essentially codified a power distribution engineers idea of low and high, while the US codified something much closer to the average laymans idea of low and high.