Is this Govenment a load of fools - part p

[ban-all-sheds]

Appliances could just as well be designed to work on DC as AC, but they would still need 100's of volts, or the cables would be ridiculously thick - something the original poster failed to realise.

 

[Big_Spark]

Appliances could just as well be designed to work on DC as AC, but they would still need 100's of volts, or the cables would be ridiculously thick - something the original poster failed to realise.

Yet another valid point.

To anyone at home the difference between AC and DC is actually academic as to have a 12V supply in your home would be prohibitively expensive due to cable size to handle the loads concerned as has already been stated ealier in this thread.

 

[20 questions]

err, well no sense in being offensive. Its says more about you as a person that it does about the poster. In this case me.

I did say that the technical issues were not understood (well I'm lazy and did not think matters through) but that my computer seems to run quite well, running cdroms, dvd drives that I replicate in my living room with ac/dc step down convertors. It is a fact that most of the consumer products are low voltage

Its also the case that USA run 110 volts for most of their equipment. Appliances requiring greater power requirements are run off 240v or so.

It seems to have provoked some debate. Anyone own a caravan? Do you run a microwave with a step up transformer. Some people do - its not impossible.

Ok, you can quote Ze Zs R1+R2 all you like. All it needs is a clearly written explanation of what it means and how to test a circuit and install to an agreed standard. Trouble is, even with experienced guys there is a lot of confusion about various aspects. Like supplemetary bonding, wiring to an external building, wiring to a garden.

Its seems that even the IEE change their mind on bonding in a kitchen - realizing that sinks are usually electrically isolated if sunk into chipboard.

Most of the work involved in a rewire of a house relates to lifting floorboards, chasing down walls and hacking out holes for socket outlets.
Yes, when it comes to a design of a house it can be tricky if cable runs are long, run in lofts at varying temps etc. However, it is amazing that it usually works to 10mm cable size for a shower up to x metres, 4mm for other runs, 2.5 for a ring circuit etc.


I do think that an electrician should be qualified to a standard

Say - Domestic installations one phase supply qualified
ditto using 3 phase another qualification

industrial to xxx etc.

The majority of work does encompass domestic - new, rewire, extensions. How do I know that someone is up to the job?

Maybe the IEE just needs to produce a standard for domestic installations that can be clearly understood. Or is that a pipe dream.

Oh, and before some plonker says no one should install if you can not understand the regs - how come so many guides to the IEE regs are published!

 

[20 questions]

Just reread the posts relating to cable size.

Ok, you have a problem with the cable size - if houses were properly designed with trunking instead of some random process of laying the cable that is only known to the sparkie, then we might be a little better off. Running cables under floorboards, buried in plaster, run in partition walls - that is crazy. It is out of sight, difficult to check for safety inspections and standards can be abused without the householder knowing.

Cost of cable - what price a life? In any event it need not be a central step down transformer - cabling could be run to an isolated cage and a step down transformer for say the living room run from there. Larger cables would therefore be shorter - less cost. If that what turns you on.

Yes, showers, cookers, washing machines, dishwashers, toasters breadmakers are a problem. We specify a separate circuit for immersion heaters, showers and cookers. Why not extend this to the higher rated items in a kitchen. We will have a lot of radial circuits - but how about it?

Non abusive thoughts please. After all, I am only a poor old s*d. But not crazy.

 

[ban-all-sheds]

err, well no sense in being offensive. Its says more about you as a person that it does about the poster. In this case me.

IMHO you opened yourself up to that by blustering about Part P, claiming that you were in the set of DIY-ers who aren't daft, and then blaming the IEE for the number of sockets we have in our kitchens, and suggesting that if houses were wired with 12V circuits things would be much safer.

I did say that the technical issues were not understood (well I'm lazy and did not think matters through)

Not thinking things through when designing, or proposing designs for, circuits is an unsafe practice. Daft, even.

but that my computer seems to run quite well, running cdroms, dvd drives that I replicate in my living room with ac/dc step down convertors. It is a fact that most of the consumer products are low voltage

Indeed they are, or could be. It is also a fact that they cannot realistically be supplied by a low voltage because the cables would be as thick as your arm.

Its also the case that USA run 110 volts for most of their equipment. Appliances requiring greater power requirements are run off 240v or so.

You mentioned that in your original post, and said that it might be safer. Not sure why - first it makes wiring more complicated, as you introduce 2 sorts of breakers (1 and 2-pole), and two sorts of sockets, and more colours to keep track of, and opens up the possibility of supplying 220V to a 110V device. Anything which complicates things and creates the potential for new and interesting fault conditions makes the environment less safe, particularly for DIY-ers.
And 110V will kill you just as readily as 240V.

It seems to have provoked some debate. Anyone own a caravan? Do you run a microwave with a step up transformer. Some people do - its not impossible.

Of course it's not. I have this nagging feeling that you simply do not believe Mr Ohm. 12V caravan microwaves (which, BTW, would be regarded as small and feeble by house standards) draw, typically, 65A. Which means a cable with a csa in excess of 10mm. For just a single small device. Am I right in my feeling? Do you still not understand that it is utterly ridiculous to suppose that we could have ELV circuits in our homes to supply all of the devices which could run from such a supply?

Ok, you can quote Ze Zs R1+R2 all you like. All it needs is a clearly written explanation of what it means and how to test a circuit and install to an agreed standard.

Such explanations do exist. There is this book for example, and it tells you what Ze, Zs etc are, and it has a whole chapter explaining testing and inspection . The IEE On Site Guide is also very clearly written. I'm sure that there are other books, but you could do a lot worse than to start with those two. Neither is very big on the practicalities of installation though.

Trouble is, even with experienced guys there is a lot of confusion about various aspects. Like supplemetary bonding, wiring to an external building, wiring to a garden.

Yes, it isn't all simple.

Its seems that even the IEE change their mind on bonding in a kitchen - realizing that sinks are usually electrically isolated if sunk into chipboard.

Apart, of course, from being connected to pipes which, if metal, will be earthed at some point. So if you grab a live thing with one hand and the sink with the other you will find out very quickly just how not isolated it is. But fortunately the wiring regs do not forbid you to bond your sink. They do not mandate it, because unlike bathrooms people tend not to be naked and dripping wet in the kitchen.

{Pause for vision of Nigella Lawson, naked and dripping wet. Do not pause for vision of Anthony Worrall-Thompson naked and dripping wet.}

Most of the work involved in a rewire of a house relates to lifting floorboards, chasing down walls and hacking out holes for socket outlets.
Yes, when it comes to a design of a house it can be tricky if cable runs are long, run in lofts at varying temps etc. However, it is amazing that it usually works to 10mm cable size for a shower up to x metres, 4mm for other runs, 2.5 for a ring circuit etc.

Indeed, but you do need to understand the calculations, and do them at first, so that you know that your shower circuit or your ring main is OK.

I do think that an electrician should be qualified to a standard

Say - Domestic installations one phase supply qualified
ditto using 3 phase another qualification

industrial to xxx etc.

Not a bad idea, but although it would shorten the time it takes to train an electrician, I don't see what other benefits it would bring. It wouldn't, for example, make them any cheaper to employ. The only benefit it might have brought, if we had had a system which recognised that to work on domestic installations only required less knowledge than commercial and industrial, would have been an official way to train DIY-ers to a level where they could be regarded as safe to do their own wiring. But since Part P is being introduced to put sole-trader electricians out of business, let alone DIY-ers, the chances of that having been allowed are smaller than a small thing that's very small.

The majority of work does encompass domestic - new, rewire, extensions. How do I know that someone is up to the job?

Just like you do with any other trades - word of mouth and generally accepted local reputation. Even NICEIC accreditation is no guarantee as FWL will attest.

Maybe the IEE just needs to produce a standard for domestic installations that can be clearly understood. Or is that a pipe dream.

No, it's not a pipe dream. It's the OSG and Guidance Notes. Seriously - if you can't understand the OSG you should not be doing any electrical work.

Oh, and before some plonker says no one should install if you can not understand the regs - how come so many guides to the IEE regs are published!

Because the regs are not easy to read, nor are they meant to be - they are (well, supposed to be) an unambiguous definition of a British Standard, laid out with the same structure as an IEC standard. Having guides is no more indicative of a problem with the wiring regulations than having the Highway Code means there's something wrong with the way the Road Traffic Acts are written. Even the IEE themselves publish a guide, written by the Secretary of the Wiring Regulations Committee.

 

[ban-all-sheds]

Just reread the posts relating to cable size.

Ok, you have a problem with the cable size - if houses were properly designed with trunking instead of some random process of laying the cable that is only known to the sparkie, then we might be a little better off. Running cables under floorboards, buried in plaster, run in partition walls - that is crazy. It is out of sight, difficult to check for safety inspections and standards can be abused without the householder knowing.

Cost of cable - what price a life? In any event it need not be a central step down transformer - cabling could be run to an isolated cage and a step down transformer for say the living room run from there. Larger cables would therefore be shorter - less cost. If that what turns you on.

Yes, showers, cookers, washing machines, dishwashers, toasters breadmakers are a problem. We specify a separate circuit for immersion heaters, showers and cookers. Why not extend this to the higher rated items in a kitchen. We will have a lot of radial circuits - but how about it?

Non abusive thoughts please. After all, I am only a poor old s*d. But not crazy.

You just don't get it, do you? Earlier on you said:

Well we seem to manage with 240 volts with size of cable - how much of an issue would it be for low voltage.

The size of cable that you need is proportional to the current it carries, not the voltage. The voltage affects the thickness of the insulation, that is all. If you reduce the voltage by a factor of 20, and want to keep the same power, you have to increase the current by a factor of 20. So 240V circuits which carry 10,20,30,40,50A would at 12V need to carry 200, 400, 600, 800, 1000A. A 10mm mains cable is good, under the right conditions for 64A. 20 times that is 1280A.

Fiddling with a bit of trunking is not going to resolve that.

If anyone here works with industrial stuff would they please post the details of the size of cable (conductor area or diameter) that you would need to carry 1280A, and how much it costs?

 

[Scoby_Beasley]

I did mention somewhere on here, months ago, that you would soon need a spark to come and turn your kettle on. £50 for a cuppa !! Best find a decent caff.
I think it's all down to the dumming down of society and allowing the lowest common denominator to be able to switch his own kettle on.
Where does it end ?? I tripped over my duvet the other night (good night out !!!), does this mean I need a professional bed maker ????????????

 

[Big_Spark]

If anyone here works with industrial stuff would they please post the details of the size of cable (conductor area or diameter) that you would need to carry 1280A, and how much it costs?

1280A would be HUGE, 400mm2 cable is rated at 683A under Ideal conditions.

According to my calculation software you would need a cable with a core size of 780mm2.

Now bear in mind that 400mm2 single cores weigh in at 28kg per meter and cost about £130 per meter, I really dread to think about the cost of the 780mm2 that would be required.

I also think that the building would need to be structurally strengthened to take the extra 10 to 20 TONS on copper cable required to wire in 12V, I also hate to think the size of the connectors on the back of your appliances.

20 Questions, once again you have clearly demonstrated you do not have clue what you are talking about and no nothing about electricity, if you think this comment an insult then perhaps you would refrain from commenting on things you know nothing about..unless you expressly state you wish to learn and ask sensible questions and listen to the replies.

 

[securespark]

hmm, now there's a thought, AWT naked and dripping wet..........!!

 

[security1]

Err - sorry to be a bit thick and that, but I have just come home in my motor car. Seems to run by something called electricity at 12v - whatever that is I do not know I am sure.

Let me see now - just gone out to look at the cable sizes - can't see any as thick as your arm. Total fuses 30. Total rated amps 505.

Ah, I get it - it has a wiring loom and of course the car itself is neg earth- whatever that is.

Of course we could not possibly use that system in a house - goodness no.

We all need self satisfied plonkers who can only think in one direction - backward and are more interested in trying to prove something wrong than a bit of lateral thinking.

Well done bas and fw thing and someone else. You make me proud to be part of the online community.

 

[Big_Spark]

Err - sorry to be a bit thick .

You said it fella

Perhaps if you read the ENTIRE thread you will understand the replies.

Also, perhaps if you had any understanding of the subject at hand you would not be so quick to comdemn the replies.

 

[security1]

Perhaps if you read the ENTIRE thread you will understand the replies.

Also, perhaps if you had any understanding of the subject at hand you would not be so quick to comdemn the replies.

Well, a consultant and educator should perhaps be a tad more tolerant and less supercilious.

I doubt very much if you speak that way to anyone in a classroom
How about addressing the point of a motor car. Tell me as a thicko , how can a car can run so many bits of equipment and not have cables as thick as your arm?

Answers, on a postcard

 

[20 questions]

Dear me Ban All Sheds.

I am sure that everyone on this forum appreciates your technical knowledge and the time and effort you spend in helping others.

It does seem to come at a price however. Blustering away at someone who has suggested something that may or may not be feasible is not a proper way to behave. Take a stress pill and go and lie down in a darkened room. You will feel much better.

One of the ways to achieve goals to set a target and work towards it.

Bluster away. Its only an idea

 

[securespark]

I've got a brilliant compromise - let's run 240 round the house and step down to 12V at the point of use...........

 

[Big_Spark]

Security, I will give you your answer, and then perhaps you will understand a little better, and also see the point that several here have been attempting to make.

The TOTAL potential current may add up to 525A, however in practice nothing like this will ever be drawn through the system.

Not every electrical part of a vehicle is turned on at any one time, and those that are on will not be running at the full load of the fuse on that circuit.

If you have an older car with a standard ignition system, then you will see the size of the cables that fed the starter motor, on small cars these could be as small as a 30A load, but on a big V8 they could be 100A or more, and these cables are LARGE, but they are also constructed differently from standard cables to help this problem. However the difference in manufacture technique will only have no more than a 10% difference in cable size.

No, to keep this sensible, Imagine a 32" wide screen TV, this does have a couple of transformers inside, one to step the 230V supply DOWN, and one to step the 230V UP to power the Cathode Ray Tube (assuming a conventional TV). At 230V the average 32" TV will pull about 8A from the supply when initially switched on, after that it will run at about 4A. Now we convert this to a 12V supply, the power used will remain the same regardless of the voltage change.

230/12 = 19.1, so therefore the current drawn at 12V will be 19.1 times that of the 230V equivilent. So we can do this.

Is = 8A
Ir = 4A
V = 230V

Therefore, 230V x 8 = 1840 watts at startup and 230V x 4 = 920 watts normally.

Now we have the power rating of the TV, we can calculate the loading at 12V, so.

1840/12 = 153.3A for the startup current, and
920/12 = 76.6A for normal operation.

Now from this loading I think you will start to see the problem, the cable size required will need to be capable of operating at normal load, plus 20% for a safe margin, therefore it should be capable of running continously with 91.92A flowing through it.

Now, as Pyro (Mineral Insulated Copper Clad cable) has the best electrical properties of any normal cables I will use that for this example, we get a smaller cable for a given loading.

From the regulation, and from my calc software we arrive at a cable that is 16mm2.

Now, Pyro is Hard Drawn Annealed Copper Cable, it is highly pure and the best conductor (copper) that can be made and sold at economic prices, yet single core 16mm2 Pyro is still over £700 per 100m role.

Further, as anyone who has ever worked with large Pyro will tell you, this is not the easiest cable to work with, and in the domestic front it would be a nightmare.

Please also bear in mind that in this example I have taken no allowance for voltage drop.

If I factor this into the equation, and assume that it is 10m from the source of the 12V supply to the TV, then I need to go up a cable size to 25mm2 otherwise the volt drop, 3.67V, would mean the TV would not operate properly as it lacked the voltage necessary.


It is not that we are slamming the idea for the sake of it, we have slammed the idea because it is simply impractical, as nice as it would be otherwise.

Perhaps as materials science improves and superconducting materials evolve to useful economic positions this will change, and I for one would welcome that change, but we are not there yet.

Further, we live is a highly complex and interwoven society, this type of change would bankrupt the nation as it would need to be implemented in one go, it would cause too much confusion to do otherwise.

Who would compel private owners to change, and spend many thousands, probably tens of thousands, rewiring their home to comply with this decree. If you thought the Poll Tax Riot was a bitch, watch the civil war that this would start!!