cable size help needed please

[taylor467]

Hi everyone. Im new here so sorry if this is in the wrong section. I have just set up on my own and been asked by a customer to install some socket outlets, lighting and electric heaters in a stable. Im goin to view the job on tuesday so ill know more about it then. But when speaking to the guy he said the stables is 250m awayfrom the house. he said there is already ducting in place with man holes to take the cable.

My question is it has been ages since i did any cable calcs (last time was at college) so could any of you kind sparks out there refresh my memory a bit with the calcs please

 

[Octopus]

You or the client, needs to define the anticipated maximum load, without this you may as well be pxssing in the wind

 

[Marvo]

What qualifications do you have?

Calculate your load, apply derating according to the tables in the regs to determine suitable cable size.

 

[Silly Sausage]

taylor, it's probably a good idea to buy this book ASAP...
Electrical Installation Design Guide: Calculations for Electricians and Designers (2nd Edition) - IET Electrical






edit....

Looks like Marv needs to change his name! :uhoh2:

 

[taylor467]

Hi marvo, I uave my 17th, nvq level 3 and so on(to be honest I cannot remember all the numbers but I am a qualifed electrician with my jib gold card) and if putting in a sub main for the stables wouldnt the max demand be 54amps 32a ring 16a radial for heater and 6a for lighting

 

[taylor467]

Thanks archy

 

[Sintra]

Hi marvo, I uave my 17th, nvq level 3 and so on(to be honest I cannot remember all the numbers but I am a qualifed electrician with my jib gold card) and if putting in a sub main for the stables wouldnt the max demand be 54amps 32a ring 16a radial for heater and 6a for lighting

With that sort of design current and length of cable you are looking at a minimum of a 70mm cable. What about applying some diversity to your loadings.

 

[taylor467]

I have serioisly fogotten to do all this stif, ive just bought the book u recomended. How do apply diversity. God I sould go back to school

 

[Mr Hehound]

I have serioisly fogotten to do all this stif, ive just bought the book u recomended. How do apply diversity. God I sould go back to school

All goes back to what loads you're going to have in the stables.

 

[D Skelton]

Open your OSG bud, it's all in there, black and white. No calcs required to apply diversity I'd also start by reducing your socket circuit to a 20A radial, that'll help a little too.

As for your design load, you're gonna need to apply diversity! lol, either that or get the ads up in the local rag for a cable pulling gang

 

[Simlec]

Hi everyone. Im new here so sorry if this is in the wrong section. I have just set up on my own and been asked by a customer to install some socket outlets, lighting and electric heaters in a stable. Im goin to view the job on tuesday so ill know more about it then. But when speaking to the guy he said the stables is 250m awayfrom the house. he said there is already ducting in place with man holes to take the cable.

My question is it has been ages since i did any cable calcs (last time was at college) so could any of you kind sparks out there refresh my memory a bit with the calcs please

Good start in using a forum as your design team!

 

[Sintra]

Have a look at this pdf which gives you the formulae etc needed. Don't slate me as this is a 16th edition document and some of the table numbers will have changed.


https://www.dropbox.com/s/8pyqwqv97za6xwl/Cable Sizing.pdf

 

[taylor467]

Why the diy section? Im not jo bloggs whos knows nothing. I am an electrician. Thanks to everyone for the advice. Ill have to get the regs book and osg out I guess. Thanks again

 

[sajeel]

Hi Taylor

Ignore some people on here are quite raw as one poster said calculate maximum load then apply diversity or calculate amps of all appliances to work out actual load then you will need to calculate voltage drop and select relevant cable

 

[Octopus]

Why the diy section? Im not jo bloggs whos knows nothing. I am an electrician. Thanks to everyone for the advice. Ill have to get the regs book and osg out I guess. Thanks again

To get the best out of the forum its a good idea to offer up your thoughts in more detail and then ask for comments!