17th edition and Tri rated cable

[stuartturbo]

For the loft
Generally is this allowed if in trucking etc as if I use 1.5mm this has a peak of 21amps so greater and a 15mV/A/m drop.
Would a sparky allow this if signing off my part P I see no reason but the greater knowledge may know.
Or is it just not worth the agro and pay the extra for twin and earth

 

[LearningSpark]

By the time you have messed about with the trunking you may aswell use T&E. No registered spark can sign your work off for you.

 

[stuartturbo]

The wire etc would be free thats all!!
and by then i may have 17th edition but not a sparky by trade!!
intended to replace current fuse board larger and using RCBO's as safer and price seems to be dropping.

I know the cable is electrically good enough it is the other areas

 

[333rocky333]

Tri rated should afaik have proper terminations on the ends unless the terminal is designed to take it, yet im sure the regulation is ignored fairly often.

 

[stuartturbo]

Proper ends would be used if you mean bootlace ferrules

 

[ban-all-sheds]

The wire etc would be free thats all!!

Can you get me a few m of 25mm² red & black?

and by then i may have 17th edition but not a sparky by trade!!

Vis-a-vis Building Regulations, you still won't be able to sign of your own work, or have anybody else sign it off.

intended to replace current fuse board

I have a feeling that you don't know what's involved in doing that.

e.g

if I use 1.5mm this has a peak of 21amps

No it doesn't.

HOMEWORK: Tell us why not.

 

[stuartturbo]

The wire etc would be free thats all!!

Can you get me a few m of 25mm² red & black?

Unfortuantly not LOL

and by then i may have 17th edition but not a sparky by trade!!

Vis-a-vis Building Regulations, you still won't be able to sign of your own work, or have anybody else sign it off.

That is a major ****er more unnecessary expenses

intended to replace current fuse board

I have a feeling that you don't know what's involved in doing that.

Currently already has RCD board so not "fuse" board I intended to split more circuits so rather than downstairs loft and upstairs the bedrooms got split when the kids are bad take out the room LOL
Already changed/installed boards for bigger stuff so this will be no issue.

e.g

if I use 1.5mm this has a peak of 21amps

No it doesn't.

HOMEWORK: Tell us why not.

not sure but
21amps is quoted as a single this drops when bunched but not looked as the wires will generate more heat
also dependent on environment

Distance will not be to great 20m ring mV/A/m so a drop of about 10V

But please educate

Best find the extra money for a tradesman

 

[ban-all-sheds]

That is a major p****d more unnecessary expenses

It would appear that that has come as a surprise to you.

//www.diynot.com/wiki/electrics:part-p

Strike 1.

Already changed/installed boards for bigger stuff so this will be no issue.

• How do you propose to isolate the supply so that you can install the CU?
  
  
• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit? You cannot assume that what's currently installed is OK, and you need to check it before starting work.
  
  
• Do you understand how the way in which cables are installed affects how much current they can carry? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?
  
  
• Which circuits should be RCD protected?
  
  
• What about the testing that you should do on your existing installation before you change the CU, if you want to be sure of avoiding grief from new RCDs tripping?
  
  
• And what about the tests you should carry out after the installation? What sequence will you do them in and at what point will you energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

not sure

If you want to design, install and test electrical installations being unsure is unacceptable.

but
21amps is quoted as a single

Not at 70° C.

And not in conduit.

Strike 2.

Distance will not be to great 20m ring mV/A/m so a drop of about 10V

Wrong.

You clearly have no understanding of Ohm's law, how ring circuits work, and so on.

Strike 3.


The thing is installing new CUs and new circuits etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

But please educate

• //www.diynot.com/wiki/electrics
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• http://www.tlc-direct.co.uk/Book/1.1.htm[/list]I suggest you get stuck into the last link right away - it won't give you design ideas, and unfortunately it doesn't refer to the current edition of the Wiring Regulations, but it's free, and will still give you a good grounding which you can augment with more up to date publications.
  
  
  

  Best find the extra money for a tradesman

  That would be best.

 

[stuartturbo]

That would be best.

Thanks for the advice and questions

I was full aware or part p but was hoping to get a fresh test before and after, as current set up was passed??
ohms law yes unless its different at 415v? assume 32amp circuit at full load 7.5ohms 240V/32A
the voltage drop just used calcs used previously for motor runs etc
A lot of the questions should be ok as it was good!!! and passed to say so
official I was to call the electricity supplier to disconnect fuse when i and a sparky to pass on the same day. Similar to the last sparky!!!!!
Must admit was not worried as i am only adding a ring as everything was good and correct#I was to protect using RCBO so was informed by tutor extra bonding not required???
I know i require B rated trip rather than the C that are in B&Q!!!
I would use in all circuits as even though protected not below 50mm old house
I would also have a proper sparky with me to test etc but not a Part P.
appears just not worth the agro to do myself
I have just appear let down every trade in house not wrong but not to my standards

 

[ban-all-sheds]

I was full aware or part p but was hoping to get a fresh test before and after, as current set up was passed??

You really did not seem aware of who may, and may not, declare that the work complies with the Building Regulations.

ohms law yes unless its different at 415v? assume 32amp circuit at full load 7.5ohms 240V/32A
the voltage drop just used calcs used previously for motor runs etc

Do you often use rings to supply motors?

And where did you get 7.5Ω from?

A lot of the questions should be ok as it was good!!! and passed to say so

But you are assuming responsibility for it all.

Must admit was not worried as i am only adding a ring as everything was good and correct#I was to protect using RCBO so was informed by tutor extra bonding not required???

What's bonding got to do with adding a socket circuit?

I would also have a proper sparky with me to test etc but not a Part P.

Then you need to apply for Building Regulations approval in advance.

 

[stuartturbo]

You really did not seem aware of who may, and may not, declare that the work complies with the Building Regulations.

Reg wise last spoke to them I can do all the work but they must test it a 2 stages ( first and final) and sign it off but i would rather give a sparky the cash direct rather than STG whom pay the sparky, And yes was fully aware that notification was required before starting work.
The only person who can declare is a Part P reg Sparky

ohms law yes unless its different at 415v? assume 32amp circuit at full load 7.5ohms 240V/32A
the voltage drop just used calcs used previously for motor runs etc

Do you often use rings to supply motors?

And where did you get 7.5Ω from?

No ring for a motors. I see a ring as 2 x 16amp in a perfect 50% split but this does not run true, but as 2.5twin and earth is rated to 24amp every allows it
7.5ohms ( V=IxR) is from 240volts divided by 32amp ring and as Tri rated the cable is down near 10ohms per km I have not allowed for the resistance of the cable yet still learning.

I would also have a proper sparky with me to test etc but not a Part P.

Then you need to apply for Building Regulations approval in advance.

Many thanks for guidance I was only looking a tri rated for cost but to prove its ok may be more agro the it's worth

Just learning LOL Looking to save a few quid and if I have to pay put it in the right pocket

 

[ban-all-sheds]

Reg wise last spoke to them I can do all the work but they must test it a 2 stages ( first and final) and sign it off but i would rather give a sparky the cash direct rather than STG whom pay the sparky,

You can't - it doesn't work like that.

The only person who can declare is a Part P reg Sparky

And only for work which he does, not for work done by someone else which he then tests.

I see a ring as 2 x 16amp in a perfect 50% split but this does not run true, but as 2.5twin and earth is rated to 24amp every allows it

1) That isn't what a ring looks like.
2) 2.5mm² T?E is not rated at 24A.

7.5ohms ( V=IxR) is from 240volts divided by 32amp ring

1) That's not how Ohm's Law works.

2) That's even more not how it works for a ring.

and as Tri rated the cable is down near 10ohms per km

1) No it isn't.

2) There's more than one.

I have not allowed for the resistance of the cable yet

An integral part of choosing a cable size - you can't not allow for it.

still learning.

Indeed, but IMO you have far too much left to learn to be able to start doing circuit design right now.

 

[stuartturbo]

Reg wise last spoke to them I can do all the work but they must test it a 2 stages ( first and final) and sign it off but i would rather give a sparky the cash direct rather than STG whom pay the sparky,

You can't - it doesn't work like that.

It does here if i read this correct and what i was told was the same

Where a person not registered to self-certify intends to carry out a notifiable electrical installation a Building Regulation application will need to be submitted together with the appropriate fee. Building Control will then arrange, through our agents, to have the electrical installation inspected at first fix stage and tested upon completion.

On the draw i have been misinformed by the way they work 30amp in a ring and 16amp single out/spur, any where i look lists T&E as 24amp. so each socket is supplied in parallel doubling the current carrying capacity

As for cable spec http://docs-europe.electrocomponents.com/webdocs/0f1e/0900766b80f1e98a.pdf
How does ohms law work i have always used the standard equation. Does it differ in a ring as it assume current draw is split/ parallel to the socket, that could draw 26amp ( 2x 13amp plug) so if ohms law states voltage divided current gives the resisance of 8.8Ohms for 230volts and the 26amp

Sorry if being a pain just like to learn stuff like this interests me

 

[heathelect]

Stuart all electrical work done in domestic premises must be certified to the local building control office.

ie-: By way of an authoritive body, NICEIC, NAPIT, ELESCA etc, or you can pay the fee to your building control office and certify it yourself.

To do this you must be deemed as a COMPETENT PERSON, clearly from your above comments you are not COMPETENT, so leave the electrics to someone who is, dont bodge it up as you or someone else will get hurt.
Enough said
Dave

 

[ban-all-sheds]

Where a person not registered to self-certify intends to carry out a notifiable electrical installation a Building Regulation application will need to be submitted together with the appropriate fee. Building Control will then arrange, through our agents, to have the electrical installation inspected at first fix stage and tested upon completion.

any where i look lists T&E as 24amp.

Not for any of the installation methods identified in 4D5.

so each socket is supplied in parallel doubling the current carrying capacity

No.

http://www.google.co.uk/search?q="ring+final"+"voltage+drop"

http://www.google.co.uk/search?q="ring+final"+"current+carrying+capacity"

As for cable spec http://docs-europe.electrocomponents.com/webdocs/0f1e/0900766b80f1e98a.pdf

1) Not at 70° C.

2) As I said - you need more than one conductor to make a circuit.

How does ohms law work i have always used the standard equation. Does it differ in a ring as it assume current draw is split/ parallel to the socket, that could draw 26amp ( 2x 13amp plug) so if ohms law states voltage divided current gives the resisance of 8.8Ohms for 230volts and the 26amp

You have a fundamental misunderstanding.

R=V/I when I is the amount of current that flows when you connect V volts across the conductor.

If you connect 230V between the ends of 10m of 1.5mm² tri-rated, or 2.5mm² T/E you'll get a damn sight more than 30A flowing, (for a short time...)

The fact that you have a final circuit rated at xA does not mean that the cable has a resistance of 230/x.

Sorry if being a pain just like to learn stuff like this interests me

I think you need to start here: http://www.google.co.uk/search?q=electrical+circuits+101