dis cable calcs

[i=p/u]

have a 3 ph tn-c-s installation and want to run from main fuses to new 3ph board 40m away..in swa

so say my ze at incommer is 0.12 i have to work out to keeep ze low enough which is fine, but where volt drop is concerned ... what is my limits on this ditribution circuit,,?

if i use 25mm cable it saying 7v which is roughly 2%...which is going to limit my ciruits at other end..? something is telling me 1% max

do i need switch fuse if using swa??? i think not

 

[keniff]

You would use a fused unit wouldn't you?

 

[i=p/u]

no id rely on the main fuses,someone else has just tapped off one phase to suplly 2 x single phase boards, but yes makes sense to avoid blowing main fuse.. as could probaly drop to 63A anyway......

 

[Guest55]

40mtrs at 100A , i'd be looking at 35mm to be honest.
you can get away with 5% v.d. on distribution circuit but as it feeding lights at the end you want only 1-2% at the DB really.

 

[44ALLAN]

1st port of call mate............what going on the end of this 'new' cable...........100amps/200amps/300amps?

Find out the max demand 1st then do all the technical calcs like the guys have shown you on here and if it comes to 25mm Swa cable then bang a 35mm in for future reference
Always works for me lol

35mm eh...........spooky that ffs

 

[Chr!s]

have a 3 ph tn-c-s installation and want to run from main fuses to new 3ph board 40m away..in swa

so say my ze at incommer is 0.12 i have to work out to keeep ze low enough which is fine, but where volt drop is concerned ... what is my limits on this ditribution circuit,,?

if i use 25mm cable it saying 7v which is roughly 2%...which is going to limit my ciruits at other end..? something is telling me 1% max

do i need switch fuse if using swa??? i think not

What load?

 

[i=p/u]

the front of shop will be coffee counter, with 2x 3 phases machine and maybe 4 x 32A socket circuits and lighting which i dont know yet but say 3 x 10A and

at the back end where i plan too take 2nd board too there will be 3 bathrooms with 4 lights 2 fans and socket for plug in smelly squirter.. and aging seating area with 3 x 32 sockets and 150 leds and back kitchen with another few lights and maybe 3 or 4 rings..... ND WHATEVER ELSE..

THIS JOB IS TO BIG FOR ME PERSONALLY BUT I CANT SHY AWAY.... TRYING TO GET GUY I WORK WITH IN BUT DONT THINK HE CAN BE BOTHERED WORKING DURING DAY THEN COMMING ONTO THIS AT NIGHTS, BUT THERES GOOD MONEY HERE... THE DRIVING FORCE

 

[i=p/u]

WELL I USED THE 100a BUT PROBABLY WOULDNT NEED THAT TO BE HONEST... 63a EACH PASE BE PLENTY EVEN 50A

What load?

 

[Chr!s]

WELL I USED THE 100a BUT PROBABLY WOULDNT NEED THAT TO BE HONEST... 63a EACH PASE BE PLENTY EVEN 50A

Well you need to assess the type of loads, when they are on etc and apply a little diversity, 150 amps for a coffee shop?

Well if you go with 50 amp, 16mm will drop 1%, that will leave you 2 % for final Circuits.

 

[i=p/u]

I KNOW THE SOCKETS CIRCUITS ARE MOSTLY FOR PEOPLE PLUGGIN IN LAQPTOPS ETC.. THE KITCHEN NORMALY HAS FARE FEW DEVICES.. BUT ALL ON 13a PLUGS