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# amps carried in cables

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#### wannabesparky

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can someone please help me to understand how many amps 1mm + 1.5mm + 2.5mm + 4mm + 6mm + 10mm twin & earth cables can carry please or put me in the right direction,
Also what size breakers are appropriate for the 1mm + 1.5mm + 2.5mm + 4mm + 6mm + 10mm twin & earth cables

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#### pushrod

cables can carry particular currents according to their csa, but then various conditions and factors will derate them eg running in insulation derates by half (i think) MCBs are there to protect the cable so should be less than the calculated current in the cable after you have taken the other factors(ambient temp, fuse, grouping, insulation etc) into account. I have been reading about it in scadden. Chapter 18 circuit design, of his book " electrical installation work"

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#### claret73

Not long gone over this at College. All the info for calculating design current, carrying capacity & fuse ratings in various tables...not hard to get head round. On site guide also has more simplified tables without the complex calcs of regs...I think?!
Must look at this amongst everything else I have to be Reading...

#### a12jpm

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If you haven't already got it buy the on site guide.

Got all the info you'll ever need for calculating stuff in a handy format.

#### acvc

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Arms
Agree with all that.

Wannabe, as far as I have learnt so far, the only sense in which you can say a particular cable size has a particular current-carrying capacity (load) is when its in a particular situation, such as surface mounted in conduit, or in a wall with thermal insulation, buried oin a wall in plaster etc etc. Each of these installation methods will determine how much current any cable can carry safely ...... because ...... the higher the temperature of the cable the higher the resistance of its conductors, and the higher the resistance the higher the temperature gets etc etc. So it's important to get it right. As pushrod, claret and a12 have said, the figures are all in the Regs and in the OnSiteGuide. Hope this helps.

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