Any electricians - cable advice

[PHB1969]

Ok....I put a new shed in the garden. I want to run power to the shed and the cable run is 35m.

With the power I want to run an led tube light (so low demand, but don't ask me how much). I also want a double 13A socket for general use, but nothing industrial - so charging a drill battery or playing a radio.

I am also in the process of constructing a pond - c 10m diameter and will want to run power to a pump which would be plugged in to one of the 13A sockets and switched on/off, but most likely will be on all the time.

I've had a local electrical firm out to quote. They suggested 35m of armoured cable running from a switched spur (?) to provide the light and socket and suggested that the power draw should be sufficient providing I didn't use lots of high demand items.

To future proof, they suggested using cable that could support 23A and if I had issues, they could take a cable from the main consumer board and join it with the armoured cable.

I've received the quote and just want to check what is required in terms of cable as I have looked on a number of electrical supplier sites and they suggest that 2.5mm 3 core armoured cable will handle 23A (some say 24A). However, I don't know if there are any other factors that need to be considered given the length of the cable run that affects this - ie do I need 6mm wire which is rated to 40+A? They haven't specified what size cable core, but the cable cost seems very high vs the prices I have googled for a 50m drum.

Any informed help would be welcomed.

Thanks

[Gurmot]

What did the sparky tell you? It looks like he's been straight with you and advised you to build in a little extra capacity in case you need to expand. It looks like you are planning on running initially from a 13amp fused outlet but with the option to upgrade to a larger (30 amp?) feed from your consumer unit if needed later.

The 2.5 steel wire armoured cable looks fine for your 13amp set up and you should get advice on how much current this will be able to carry if needed. If it is buried, this will make a difference.

Another question I would have is how you will feed both lights and sockets within the shed as the lights will need to be protected by a smaller (6 amp) fuse. Small consumer unit in the shed or a fused spur outlet?

[BDStevens]

The 2.5mm cable will be okay on max 25A MCB (if you can actually get one for your consumer unit - if not it'll have to be 20A). The supply can be taken from a 'spur' in which case max supply will be 13A. I would suggest go for connection from the consumer unit if the cable route is feasible - you won't want to alter it later if you're not an electrician. If you take the supply to the shed ideally (if you can afford it) get them to install a 'garage unit' which is a small consumer unit with 2x outgoing ways (one for lighting and one for power). If not, the SWA can gland into a metalclad socket and then a spur for the light (or plug in a lead light along with the pond pump into the socket). If you want to future proof the supply then by all means go upto a 4mm or even 6mm cable for greater current carrying capacity, but little point if you just come of a 13A fused spur unit.