3 Phase cable size confusion? for workshop.

[Taffbats]

Hi Gents

I'm confused about what size 3 phase cable I should run from my meter to my workshop? I recently had a new supply put in (80 amp) 3c-25mm cu service cable to the top of my drive, and there is another 35 meters to the distribution board, Western Power tell me to carry on with the 25mm, but a sparky I had quote me suggested 50mm with a 25mm earthing cable to reduce voltage drop, wouldn't going up to a larger cable have the opposite effect?

Regards
Kev

 

[JohnW2]

I'm confused about what size 3 phase cable I should run from my meter to my workshop? I recently had a new supply put in (80 amp) 3c-25mm cu service cable to the top of my drive, and there is another 35 meters to the distribution board, Western Power tell me to carry on with the 25mm, but a sparky I had quote me suggested 50mm with a 25mm earthing cable to reduce voltage drop, wouldn't going up to a larger cable have the opposite effect?

No - the larger the cable size, the less would be the voltage drop for any given load.

Whether voltage drop might be enough of an issue to justify going up to a larger cable size would depend on the maximum load you envisaged running in the workshop (hence through the cable) - can you give us any idea of what that might be?

Kind Regards, John

 

[Taffbats]

I think from memory with all my machines running (lathe, milling machine, etc) which would never happen, was around 25kva.

Kev

 

[flameport]

25mm² is plenty for that distance, even if you use the full 80A.

5 core 25mm² SWA and a suitable switchfuse, once the meter has been installed.

 

[Taffbats]

Thanks for your replies guys.