A few questions on wiring practices

[peterh337]

OK; thanks. I will go for Plan B for the supply - dig 50cm down in the garden.

What sort of stuff are they looking for in terms of connecting their meter to?

Is it enough to provide them with a nice cabinet, with space at the bottom for the meter, and with the four 25mm2 wires, plus a 16mm2 earth, coming in via a duct and joining to a 100A 3ph CB? The wires are 6381Y double insulated extra flexible, all correct colours etc, because the more usual stiffer type would not have gone around the bends.

Do they prefer plastic or stainless? I know on new meter installs they use a cheap and nasty plastic box which is not sealed. I would prefer either a fibreglass or a stainless one with a proper seal.

Is there a requirement for an RCD at that point (perhaps a 100A RCBO)? AIUI if you have an RCD feeding other RCDs (as we would have in this case) then the head RCD is 100mA and that offers no shock protection.

Now I have a funny Q. Let's say, when they are digging the 50cm trench, they find some cables (supplies to other houses nearby, but passing under our plot) which are nowhere near the regulation depth. Say they are 20cm deep. What will they do? Will they say "this was legal in 1960 when they were put in by us" and leave them, or will they insist on digging them all up?

 

[SPECIAL LOCATION]

Also meant to say...

Whatever practice you have done in the past running SWA supplies at old properties is pretty much irrelevant to the standards required today..

As you must remember how both supply and demand on the distribution networks are changing significantly over recent years..

i.e. Solar stuffing loads more power back into the grid..

Electric Vehicles drawing loads more out of the grid..

So significant parts of the distribution network are under much greater load than they were ever designed for..

The cables up to your cut-out and meter are the supply companies responsibility...

So they will call the shots...  (that bit is their bouncy castle!)

And they may well have changed what they consider acceptable compared to your past experiences..

Anecdotes about a few experiences from a minority of electricians..  is not a valid reflection on the whole of the industry..

Any more than saying all Vauxhalls are rubbish because one company car I had several years broke down still within its warranty.

Electrical installations in rented properties are considered more likely to suffer deterioration than a private dwelling.. (Hence the shorter intervals between periodic inspection & testing for rental dwellings).  

So an electrician may take a more thorough approach before issuing any paper work with their signed declaration that it is electrically satisfactory..

Just I would expect someone purchasing a second hand rental car to give it a bit more due diligence than a single private owner purchase of the same make of car..

Just because someone has done something in the past does not mean it is right or safe to do now..

Kids used to play football in the street when I was younger..

And 99.99999% of dual carriage ways were 70mph speed limit...

But today things have changed due to risks and dangers..  too many cars to play in the street..

and vast swathes of dual carriage way have been changed to 60mph or 50mph or single lane or centre gaps closed..

or any combination thereof..

To say I am going to tell my kids to play in the street while I go for a 70mph drive down the nearest dual carriage way...

because that's what I did 30years ago at our old house... is just daft.

Change happens across all industries, including the electrical industry...

But wiring regulations are not retrospective..

And there is no obligation to update a whole installation..

But ALL new work should be done to comply with the current wiring regulations..

However you should also not just add bits to an existing installation that is dangerous!

The idea of an RCD replacement in nuisance tripping came from an electrician, in cases where the leakage was measured well within spec. An RCD is quite simple (basically a transformer with 2 windings with some other bits) but they can develop faults after many years.

Are you saying the RCD operating characteristic were correct and within spec..?

But you still changed it??? 

Or trying to suggest that fault currents have some sore of pre-defined value they will never exceed...?

Or saying that actually the RCD was operating too sensitive and tripping below 15ma?

(I think you will find that most on here understand what an RCD consists of, how it works and what potential faults can arise..

And have probably a tad more experience of investigating RCD tripping faults than your experience...

RCD's can become oversensitive..

But more often than not, if they do fail.. they stick so they don't operate at all!

Generally what customers consider a nuisance tripping problem, is actually a poorly designed installation and the RCD doing exactly what it was designed to do.) 

:coffee

 

[UNG]

There are times when you look at a thread and think why I didn't train to be a rocket scientist as I could still do electrical work and this thread falls into that category

The OP is displaying a certain arrogance and a lot of ignorance with his posts so far and I'm beginning to think he cannot find a decent electrician to advise him because all he wants to pay is peanuts and therefore not getting the best advice and options from the "electricians" he uses.

I have walked away from a lot of prospective customers who thought they knew better than I did as you know it will all end up with accusations and acrimonious confrontations

Up to now the OP seems to not understand the difference between illegal and non compliant work and the comments made regarding electricians he has used in the past seem to be possibly misreported or misquoted to give a negative impression of the trade while promoting the "high" standard of his untested uncertificated DIY work

For the OP's information a 30mA RCD fresh out of the box will normally trip somewhere between 23 - 27mA therefore giving a bit of tolerance. If I was called to an installation with a tripping RCD and found a single appliance leaking 30mA+ I would unplug it and suggest it was repaired or replaced before it killed someone

It is not clear what the OP's location is but before digging trenches and carrying out any installation of three phase equipment I would suggest that the OP contacts the DNO regarding availability of a 3 phase supply at the capacity he needs and a quote for installation and the DNO's site requirements, I've not done any 3 phase installation applications for around 20 years but the quote that came in for one was for many tens of thousands due to needing local network reinforcement and required the customer to provide a suitable area of land and a concrete base for a packaged substation to be sited on another I can't remember how much it cost but it was a house in a rural area and needed a 3 phase supply cable to replace the existing single phase supply across a field the customer wasn't bothered by cost as he had spent 750k on a barn conversion and another 30 or 40k for the supply upgrade was pocket change. You may also find that requesting a 3 phase connection for future use will be knocked back by the DNO as unnecessary

 

[peterh337]

There is a 3 phase cable running about 3m from the property boundary, and this is about 10m from where the meter would be. That cable is about 2-3" OD. There is a property about 10m away from our property boundary which already has 3 phase. So I doubt it would be more than a few k, especially if I dig the 10m bit myself.

About 25 years ago I paid 1k for 3 x 35mm2 3 phase to be connected up, fused at 100A per phase. There was 3ph on a pole about 30m away and they installed one more pole and ran it all overhead.

On the RCD topic, obviously a (say) 20mA leaky item should be chucked out because 20mA is plenty enough to kill, but what if it is a brand new Miele oven+hob? Not uncommon because the ceramic insulation in the oven heating element (fan assisted oven) has moisture in it initially and leaks. C**p, for sure, but Miele is the most expensive German brand. A Miele fridge-freezer was not much better. An AEG air extractor, whose fluorescent light trips the RCD, from brand new. It's easy to be a purist if one can walk out of the house saying the appliances are c**p, but think of the homeowner too. That's why a lot of houses were, for decades, wired with a non-RCD socket for the freezer. It's called "nuisance tripping" and a lot of the time nothing is found, and then it trips again a few weeks later. Most likely it is condensation on some connections, possible because consumer stuff is rarely sealed properly.

 

[Sharpend]

Would it be easier to ask what you don’t know about? 
so 20mA can kill, so I guess the whole electrical industry got it wrong with saying 30mA is the limit. But clearly you know best about nothing, my advise is that perhaps you should stick to what you have actually trained for and stay out of what you know little about, you are what is called Dangerous- little knowledge and all that. 
I think given that you have come to an electrical forum which houses many experienced electricians then you should heed the advice so far given, as all you are doing is insulting our intelligence. 

 

[peterh337]

Let me put the questions again. These are questions i.e. things I don't know

What sort of stuff are they looking for in terms of connecting their meter to?

Is it enough to provide them with a nice cabinet, with space at the bottom for the meter, and with the four 25mm2 wires, plus a 16mm2 earth, coming in via a duct and joining to a 100A 3ph CB? The wires are 6381Y double insulated extra flexible, all correct colours etc, because the more usual stiffer type would not have gone around the bends.

Do they prefer plastic or stainless? I know on new meter installs they use a cheap and nasty plastic box which is not sealed. I would prefer either a fibreglass or a stainless one with a proper seal.

Is there a requirement for an RCD at that point (perhaps a 100A RCBO)? AIUI if you have an RCD feeding other RCDs (as we would have in this case) then the head RCD is 100mA and that offers no shock protection.

Now I have a funny Q. Let's say, when they are digging the 50cm trench, they find some cables (supplies to other houses nearby, but passing under our plot) which are nowhere near the regulation depth. Say they are 20cm deep. What will they do? Will they say "this was legal in 1960 when they were put in by us" and leave them, or will they insist on digging them all up?

 

[Sharpend]

I believe this was answered in one of the very first posts by a member, along the lines of Ask them and they will tell you exactly what they want and expect. Be sure that if you do anything not to what they ask they will walk away from the job until it has been corrected. I have seen this happen even on commercial jobs, oh and should it happen don’t expect them back anytime soon as they will reschedule the job to the back of the queue. 

 

[SPECIAL LOCATION]

That's why a lot of houses were, for decades, wired with a non-RCD socket for the freezer. It's called "nuisance tripping" and a lot of the time nothing is found, and then it trips again a few weeks later. Most likely it is condensation on some connections, possible because consumer stuff is rarely sealed properly.

Whilst this may be a true anecdotal illustration of your very limited experience of a handful of domestic electrical installation within the UK..

It is  once again a flawed concept.. 

Clearly you haven't been inside that many houses..... 

As there are absolutely buckets loads of housed fitted with boards that have a single 3Oma RCD as the main switch..

and the types of appliances you describe...

Which was a trend decades ago...  even before the split-load-board craze hit....

 
So they have absolutely no non-RCD circuits at all !!! 

and the whole darn installation trips of if you have an earth leakage fault..

Poor wiring practices, inadequate installation methods and badly designed final circuits are just as likely to cause RCD's to trip as your assumptions about dodgy appliances.

opcorn

 

[roys]

Yip my house has an upfront RCD as main switch protecting the whole board, MK Sentry, installed by me in 1987, but times change and I have just installed a full DP RCBO board (from sbs Dave) into a house I am about to move to.

To your questions, I can answer one of them but it all depends on the day when the distribution tech / engineers arrive, my mate had just installed a monster steel enclosure for the DNO to put their kit, (he was also mounting a lot of his own kit in it). The DNO refused to mount their kit as there was no wooden back board, he made them a coffee, and 15 minutes later he had a 20mm ply backboard mounted in it.

 

[SPECIAL LOCATION]

Let me put the questions again. These are questions i.e. things I don't know

What sort of stuff are they looking for in terms of connecting their meter to?

Is it enough to provide them with a nice cabinet, with space at the bottom for the meter, and with the four 25mm2 wires, plus a 16mm2 earth, coming in via a duct and joining to a 100A 3ph CB? The wires are 6381Y double insulated extra flexible, all correct colours etc, because the more usual stiffer type would not have gone around the bends.

Do they prefer plastic or stainless? I know on new meter installs they use a cheap and nasty plastic box which is not sealed. I would prefer either a fibreglass or a stainless one with a proper seal.

Is there a requirement for an RCD at that point (perhaps a 100A RCBO)? AIUI if you have an RCD feeding other RCDs (as we would have in this case) then the head RCD is 100mA and that offers no shock protection.

Now I have a funny Q. Let's say, when they are digging the 50cm trench, they find some cables (supplies to other houses nearby, but passing under our plot) which are nowhere near the regulation depth. Say they are 20cm deep. What will they do? Will they say "this was legal in 1960 when they were put in by us" and leave them, or will they insist on digging them all up?

In all your info so far you have made no mention of the current earthing arrangements.. 

On the one hand I was guessing TT due to mention rural and 100ma upfront RCD...

BUT.. as you say you have socket(s) without 30ma protection maybe not..?

as how are you meeting your Zs values for max disconnections times if its TT.. unless its a damn good Ra on your rod   ?

Have you verified your single core double insulated cables are specified as suitable for being buried in duct,  or are they intended just for surface wiring ?

You don't want moisture seeping through to the conductors if they become submerged due to the duct filling with water.

What considerations have you made about potential problems of eddy currents with your individual 3-phase conductors?

100ma & 30ma RCDs in series offer no discrimination for any faults 100ma + 

Unless your have omitted to mention the full RCD type?

The best answer to ALL of your questions is..    CONTACT YOUR DNO..

ask them to do a site survey and tell you what they need and what bits you can do...

Guessing and hypothesising about what scenarios could happen, then re-asking the same question is unlikely to get much of a different answer TBH.

opcorn

 

[peterh337]

The current feed looks like a coaxial cable and the neutral of it is connected to the earth in the house, so not TT. Also there is no earth rod anywhere. The earth is also bonded to various water pipes. However this feed will become redundant when 3ph goes in, so it will depend on what the power company wants to provide. Most likely the same as present.

There is no 100mA RCD.

Could you please explain eddy currents? I know what it is but what's the relevance of wires next to each other over say 5m distance, which one would not have in say an SWA cable?

Very funny story Roys and I can totally believe it  I've seen all from really nice to totally anally ******** jobsworths. Same with BT; just had FTTP installed.

 

[UNG]

There is a 3 phase cable running about 3m from the property boundary, and this is about 10m from where the meter would be. That cable is about 2-3" OD. There is a property about 10m away from our property boundary which already has 3 phase. So I doubt it would be more than a few k, especially if I dig the 10m bit myself.

About 25 years ago I paid 1k for 3 x 35mm2 3 phase to be connected up, fused at 100A per phase. There was 3ph on a pole about 30m away and they installed one more pole and ran it all overhead.

There you go again with your assumptive arrogance just because you have a cable passing your property boundary doesn't mean you will get the supply you want, around 30 years ago I put an application in for a supply upgrade to a large workshop that was across the road from a substation and was told that without a substation upgrade and network reinforcement it was not available can't remember the costs but if the customer paid for it and then other customers in the locality needed supplies then my customer would get a %age rebate of his payment

It has always been the case that customers can mitigate costs by carrying out the excavation works, backfilling and builders works to the DNO's specification

As a comparison to your historic pricing 17 years ago I needed a single phase 10 KVa supply to a comms mast site about 100m overhead to the nearest DNO overhead network point the quote was £120k what you have to factor in is that privatisation has significantly changed the the DNO pricing landscape as they no longer sell the electricity to the end user

On the RCD topic, obviously a (say) 20mA leaky item should be chucked out because 20mA is plenty enough to kill, but what if it is a brand new Miele oven+hob? Not uncommon because the ceramic insulation in the oven heating element (fan assisted oven) has moisture in it initially and leaks. C**p, for sure, but Miele is the most expensive German brand. A Miele fridge-freezer was not much better. An AEG air extractor, whose fluorescent light trips the RCD, from brand new. It's easy to be a purist if one can walk out of the house saying the appliances are c**p, but think of the homeowner too. That's why a lot of houses were, for decades, wired with a non-RCD socket for the freezer. It's called "nuisance tripping" and a lot of the time nothing is found, and then it trips again a few weeks later. Most likely it is condensation on some connections, possible because consumer stuff is rarely sealed properly.

Ahh the German engineering thing it must be good because it's expensive the fact that it leaks excessive current out of the box doesn't matter

Back in the days of the ELCB it was common to install circuits that had no ELCB protection freezers and electric cookers were always good for unnecessary tripping of the ELCB, since the RCD I can't recall ever installing a non-RCD socket for a freezer and it certainly in my opinion never happened for the decades like you state. With regard to your definition of nuisance tripping it clearly demonstrates a total lack of knowledge and understanding, you have obviously never investigated the auto defrost cycle of a fridge or freezer that has a failed heating element once the power drops the auto defrost timer resets and there is no fault to find wait a few days or weeks and it happens again it ain't nuisance tripping it is a fault isn't is amazing what having the correct test equipment can prove. For me nuisance tripping is when the RCD has become more sensitive and trips at a level well below the normal 23 - 27mA that a new RCD usually trips at

 

[peterh337]

The level of personal abuse here, levelled at somebody who expressed personal views etc but didn't attack anyone else here, is impressive.

As someone involved in running certain online sites for years, I hope the mods here are suitably proud.

 

[Murdoch]

The level of personal abuse here, levelled at somebody who expressed personal views etc but didn't attack anyone else here, is impressive.

As someone involved in running certain online sites for years, I hope the mods here are suitably proud.

mate, you’ve come on here expecting people to spoon feed you information. 
 

as my last post said, the vast majority of us on here earn a living doing this so why would you expect people to give away decades of hands on experience?

think about it 

 

[Sharpend]

They were not your views but what you believed to be correct, which was wrong sorry you can’t take the criticism 

 

[peterh337]

mate, you’ve come on here expecting people to spoon feed you information. 
 

as my last post said, the vast majority of us on here earn a living doing this so why would you expect people to give away decades of hands on experience?

think about it

Yes, I can fully see that, but why then do you spend any time helping people on an internet forum to start with?

People should get a life, and participate only if they want to help somebody. Not moan that by answering questions they are losing money not getting work. I guess all the electricians here are silently hoping that they will get jobs by half answering questions. But that won't work unless they advertise their locations.

Oh another thing, re use of social media to get business. Something I know quite a lot about, semi-professionally. Be polite and helpful. For every 1 posting here there are 1000 reading and most of those will make a quiet note to themselves to never professionally engage anyone here with the attitude shown. Electricians already have a pretty bad reputation in the attitude department. Even worse than builders. Why? I am not sure but in many areas they can print their own money, and they are lazy on the jobs they take on. A lot of them are dishonest by asserting certain regulatory requirements, which is easy to do even with "professional" customers because the regs are so damn complicated. I'd say 100% of electricians who worked on my business premises in 20 years were dishonest re regs.

Re making money from forum posts, there is a forum I know on which one trade guy was making 50k/year (conservative estimate; that was just the jobs I knew about from people I knew who used him). High margin work, too. You would think he would be polite as hell, wouldn't you? Easy money, 15 mins a day on a forum to get 50k. No, he kept beating up the admins! Eventually his wheels came right off and ... they banned him. 50k p.a. down the drain. Years later he is still bitter as hell. And still doesn't get it.

They were not your views but what you believed to be correct, which was wrong sorry you can’t take the criticism 

What you are not getting is the key difference between personal attack, and a disagreement.

On properly run moderated forums, one allows unlimited technical disagreement, but zero personal attacks. I could give you examples but it would be a waste of effort because it is really obvious to anyone who can read.

Anyway, I have clearly exhausted the willingness of the electricians here to help somebody out, before they can get some £££ off me. BFN and good luck.

 

[SPECIAL LOCATION]

OK, fair enough, feel free to attack a new poster. I know the scene well; it's no problem. In the meantime, someone might post some useful info.

This is not my bouncy castle but the general idea is to play the ball not the man.

The level of personal abuse here, levelled at somebody who expressed personal views etc but didn't attack anyone else here, is impressive.

As someone involved in running certain online sites for years, I hope the mods here are suitably proud.

No attacks????

I guess some may beg to differ on that one...

with comments suggesting people haven't provided useful info...

Or what was the constructive element of comments about bouncy castles and playing ball...   

As for implying the Mods are not as aware as you are at running online sites for years...

The fact that you say you know the "scene well" suggests you are the one with an attitude of not being able to take constructive criticism possibly from other forums I guess..?

Either way some of your personal views about how this industry works are incorrect and fundamentally flawed...

So it very unlikely anyone with more comprehensive qualifications and experience within the sector of work you are inquiring about is going to agree with you...

We have seen it time and time again over the years...

Someone comes on talking about how good they are at everything...

therefore thay are unable to comprehend the short comings in their knowledge when questioned.

:shakehead    

 

[SPECIAL LOCATION]

Yes, I can fully see that, but why then do you spend any time helping people on an internet forum to start with?

People should get a life, and participate only if they want to help somebody. Not moan that by answering questions they are losing money not getting work. I guess all the electricians here are silently hoping that they will get jobs by half answering questions. But that won't work unless they advertise their locations.

Oh another thing, re use of social media to get business. Something I know quite a lot about, semi-professionally. Be polite and helpful. For every 1 posting here there are 1000 reading and most of those will make a quiet note to themselves to never professionally engage anyone here with the attitude shown. Electricians already have a pretty bad reputation in the attitude department. Even worse than builders. Why? I am not sure but in many areas they can print their own money, and they are lazy on the jobs they take on. A lot of them are dishonest by asserting certain regulatory requirements, which is easy to do even with "professional" customers because the regs are so damn complicated. I'd say 100% of electricians who worked on my business premises in 20 years were dishonest re regs.

Re making money from forum posts, there is a forum I know on which one trade guy was making 50k/year (conservative estimate; that was just the jobs I knew about from people I knew who used him). High margin work, too. You would think he would be polite as hell, wouldn't you? Easy money, 15 mins a day on a forum to get 50k. No, he kept beating up the admins! Eventually his wheels came right off and ... they banned him. 50k p.a. down the drain. Years later he is still bitter as hell. And still doesn't get it.

What you are not getting is the key difference between personal attack, and a disagreement.

On properly run moderated forums, one allows unlimited technical disagreement, but zero personal attacks. I could give you examples but it would be a waste of effort because it is really obvious to anyone who can read.

Anyway, I have clearly exhausted the willingness of the electricians here to help somebody out, before they can get some £££ off me. BFN and good luck.

Well that lot just shows more mis understanding about the purpose of social media...

:slap ROTFWL :lol:

It is NOT all about using it as a platform to attempt to get any work...

Sounds a bit more like you are the one with the bad perception of electricians...?

 

[Murdoch]

Yes, I can fully see that, but why then do you spend any time helping people on an internet forum to start with?

People should get a life, and participate only if they want to help somebody. Not moan that by answering questions they are losing money not getting work. I guess all the electricians here are silently hoping that they will get jobs by half answering questions. But that won't work unless they advertise their locations.

Well .......... I look on here each day to see if any of the sparks are looking for products or have issues with installations or sometimes awkward customers ..........

If you look at a lot of the threads they have little or nothing to do with sparking - its a reflection that a lot of us work on our own and this type of forum is a "replacement" for the tea break banter

I'm not moaning about this at all - just not helping you - there is a huge difference.

Why don't you share YOUR location and see if anyone on here is willing to work for you?

 

[kerching]

So you have been spanked by every sparks regarding the regs for twenty years?.....what does that tell you?

the DNO write their own rules, end of. If you just randomly guessed about the ducting and it is wrong then "lesson learned" surely?

if the DNO says the duct has to be at a set depth, pink with an orange stripe, installed on a Tuesday.  Then that is what it has to be. It's not their problem, deal with it.

and shouldn't all this have been in the DIY questions section and not in "Introduce yourself"?

just saying