Need help thanks

[amcevoy]

I have a circuit consisting of a single pahse 230v radial circuit serving 3x 2kw fan heaters. 2.5mm squared pvc single core cables instaled in pvc conduit and metal trunking clipped to the surface. A single phase consumer unit with 20A mcb protection. Other info provided is: measured earth fault loop impedance is 0.57 ohms and the measured prospective fault current is 0.4kA.

What other other info do i need to undertake cable calcs? am i right in thinking its just the 4 factors plus cable length? - ambient temp, grouping, insulation and type of protection?

How do i work out the expected voltage drops and the current at each load? - what is the formulae?

Thanks

Andrew McEvoy

 

[SPECIAL LOCATION]

Volt drop is per amp per meter..

using 6E2 on page 133 of on site guide it has values for all standard cable sizes.

you can see 2.5mm is 18mV/A/m

so if your circuit was 28m long and was taking the full 20amps at the furthest point, the volt drop would be:-

(18 x 20A x 28m) / 1000 = 10.08v

you dived by 1000 cus the 18 is in miliVolts.

so to do your calcs we need some lengths?

Spec Loc.

 

[sellers]

if you have your R1 + R2 you can calculate the length aswell.