Is this existing SWA cable useless?

[STEVEROG]

I've got a SWA cable running from my house down my garden into my shed. I've just had a closer look at it and its only 2.5mm.......the cable run is 50m from house to shed! All buried.

Now, the cable is supplying sockets and lighting. I think this cable is undersized from a volt drop point of view but I might be wrong, anyone?

I think I therefore need to replace with a 4mm SWA cable.

Can I use this or is it game over for this cable?
I'm sure that for lighting only it would be fine but I want sockets. I think it's game over......I'm clutching at straws.

 

[winston1]

Do the lights dim noticeable when you use the sockets? If not 2.5 is OK.

 

[Taylortwocities]

The volt drop issue ius a factor of the current that is being drawn.

2.5mm² may be fine if all you are powering is a drill and a couple of lights.
You would only notice the VD problem if you plugged in a kettle, or a two-bar electric fire.

So, please tell us what you are planning to plug in and what would be the expected maximum demand on that circuit, we can then give you a better opinion.

 

[flameport]

To comply with volt drop it's only good for a couple of kW.

However you could probably load it up rather more than that provided the lower voltage was not an issue for whatever loads were in use. Also depends on what the voltage at the origin is.
Note that doing such a thing does not comply with BS7671.
Also consider that you can buy 50m long extension leads rated to 13A, some with multiple outlets at the end, and they are made from flex significantly smaller than 2.5mm

If replacing, 4mm would seem a rather pointless waste of money, 6 or 10 would be a better option given that most of the time & cost will be the installation, rather than the cable itself.