formula

[SteveKent]

Hi All,

Been reading with interest and was wondering on the following...

1, new shed installed....50 m from indoor CU....

2. was thinking of using SWA and run U/G (groan..a long days work..)

and was thinking...

Q. is their a formula rto work out the Voltage drop (VD) over this run, and is it just too far...what do I need to do?

I will need to have maybe 2 sockets and lights..and estimate around 20A of load at most...with normal being just power tool,, fridge for beers...TV

And is 4mm or 6mm SWA ok?

looking forward to replies on how best to tackle.

Regards

Steve
___________________________________________
Moderator

split from "hi jacked" question

 

[ban-all-sheds]

Hi All,

Been reading with interest and was wondering on the following...

1, new shed installed....50 m from indoor CU....

2. was thinking of using SWA and run U/G (groan..a long days work..)

How many times do you want to dig the trench to bury cable?

and was thinking...

Q. is their a formula rto work out the Voltage drop (VD) over this run, and is it just too far...what do I need to do?

Yes there is. You need to find the info on voltage drop for the cable you will be using (usually expressed in terms of mV/A/m), and multiply that by the current and distance involved.

Or you could just go here: http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

I will need to have maybe 2 sockets and lights..and estimate around 20A of load at most...with normal being just power tool,, fridge for beers...TV

And is 4mm or 6mm SWA ok?

4mm² NBG. 6mm² OK, but getting up to the limit on VD - over my personal 50% rule-of-thumb. See my first Q above. Stick in 10mm² then you won't have to dig it up if you decide to add more stuff down there. The difference in cost is pretty minimal in the overall scheme of things.