Shed Power: DIY

Wednesday, April 8th, 2015


Shed Power: DIY

If you?re blessed with a big shed, and haven?t filled it with junk, then you?ve got the perfect place in your garden to create a powered pad. If you fancy having a go at powering up your shed then read our helpful guide.

Man cave, office, workshop or a place to send the kids?


When the kids are running round screaming, the wife?s manically hoovering or the teenager?s bass line is pumping through the floor a bloke will often look longingly at their shed wondering about the possibilities of making it into something great. It could be your very own man cave, office, or even a place for the kids to play games, watch movies and get out of your hair.

All this is possible when you power up your shed with electricity!

Solar vs Mains Power

But what should you use to power your shed?


Solar energy is becoming more popular due to Government grants, so prices have dropped recently and efficiency has increased. With solar, you could go a simple route and just install lighting or if you’re looking to push your shed’s boundaries then you’ll need to go for a more advanced setup.


Just want to be able to see if your picking up a 10mm spanner and not a flat head screwdriver? Then a simple solar powered light might be your answer.

small-solar-light-1 small-solar-light-3

This solar light is charged by a crystal solar panel and the light fixture holds 24 LED Lights. A fully charged light will last about 5 hours and will recharge when the sun rises. You just attach the light fitting to your shed’s ceiling or wall and the solar panel on the roof or side cladding. Aside from taking zero DIY skills and less than 15 minutes to do, it won’t break the bank.

solarpoweredshedlight small-solar-light-2

You can buy these lights from ebay (search for solar shed light) or garden centres and shouldn’t cost more than £10.


Are you looking for a more scalable, beefy set up? Don’t blame you! A 600W system is the bare minimum you’ll need to turn your shed into a power house!

600w-solar shed-lighting

This system, which you can buy from ebay for £600, includes the solar panels, connectors, mounting kit, solar controller regulator with timer and light sensor and MC4 cabling. You will also need to buy a couple of special batteries to store the energy so you can hopefully beat the overcast English weather! (A full 600W kit can be bought by searching for ?solar panel kit 600W with battery? and will cost around £800). Don’t forget this is just the power, you’ll also need to buy everything else to make use of it, e.g. lighting and plug sockets. Here’s a load reference table so you can see what you can run using a 600W system in your shed.

Name of Load Power(W) Quantity Working Time per Day (H) Working Days
Color TV 65W 1 6 2 days
Satellite TV Receivers 25W 1 6
LCD Computer 100W 1 6
Energy-saving lamp 11W 12 6
Printer 30W 1 2
Refrigerator 100W 1 3

You may find the British weather hampers your efforts in that you can’t power your office or workshop all year round, so you may want to install more solar cells than what you think you can get away with so that you capture all the available sunlight!


A mains powered shed will cover all possible uses. And it is an affordable and easy option, as kits for outdoor mains electricity (lights, light switch, power points, consumer unit) can be purchased from under £500 including installation.

inside-tool-shed inside-tool-shed1

For a little bit extra you can add on alarms and outside entrance flood lights too.

shed-alarm-pigs shed-floodlight

DIY Mains supply

You will need to get the shed wired to your mains supply, this can be difficult and potentially hazardous for a DIY-er. When it comes to selling the property or just for your piece of mind you should use a competent electrician who can complete domestic Part P Electrical Safety work. The electrician may need to make changes to your fuse box to support your new cable; this could include the addition of an RCB (Residual Circuit Breaker; safety device that cuts the power in case of problems such as cut cables or damp) and an MCB (Miniature Circuit Breaker; a safety device that cuts the power in case of overloads and also acts as an on/off switch) . It is possible to do this yourself and get it signed off but the difference in cost/effort does call that idea into question.

If you do intend on doing this yourself or if not just so you can be prepared for an electricians questions, we spoke to Matt from about running electrics from your mains fuse board to your shed,

?Depending on the distance of the run from the incoming supply point to the position of the furthest electrical device in or out of your shed, you will need anything from 4 to 25mm, 2 or 3 core armoured cable. If you are running downhill and going around bends you will need to factor that in to your calculations as to what thickness of cable you’ll need…? (see calculations below)

?I always allow for at least a 16amp radial circuit in the shed. This is enough to comfortably run power tools, office equipment and a tumble dryer (not all at once). You should carefully consider what you intend on running in your shed. Write a list and work out the expected current and power requirements for each item. Also consider if you intend on running a heater in cold weather.?

An example of a list may be:

In shed (25 metres away)

- Heater 2000w

- Kettle 3000w

- PC 150w

- Power tools x 2 3200w (1600w each)

- Lights inside shed – 150w

- other small electrical items ? 200w

( total: 10kW max )

Exterior Lighting (45 metres max away from shed)

- 2 x 200w flood lights

- 2 x 100w up/down lights

- 16 x 50w uplighters (run on 12v transformers)

( total: 2kW max )

?You could take into account diversity, as perhaps not all items will be on at once. For example you won’t be working when the kettles boiling! But for the sake of simplicity we should assume all devices are on.?

These are the calculations you need to do to assertain what cable size you need:

Supply voltage = 230 Volts
Ib = design current = 30 Amps
Protective device type = MCB type B
In = protective device rating = 32 Amps
Length of run of cable = 70 metres
Power factor = 1
Cable Type : Thermosetting 90°C ARMOURED – Multicore
Installation Method : Sheathed, armoured or multicore cables direct in the ground: without added mechanical protection.
Ambient temp = 20 °C
Number of circuits including this one = 1
Length of cable in thermal insulation = none
Correction factors:
Cg = 1 (Grouping)
Ca = 1 (Ambient temp) – Ground Temperature : 20 °C
Ci = 1 (Insulation)
Protective device factor : Cc = 0.9 (buried direct)
It = tabulated current carrying capacity
It = In / (Cg x Ci x Ca x Cc)
It = 32 / (1 x 1 x 1 x 0.9 )
It = 35.56 Amps
Cable selected = 4 mm²
For 4 mm², mV/A/m = 12
mV/A/m corrected for power factor = mV/A/m x Power Factor = 12 x 1 = 12
Volt drop = (mV/A/m x Length x Design current) / 1000
Volt drop = ( 12 x 70 x 30 ) / 1000
Volt drop = 25.2 Volts
(Maximum permissible volt drop (regulation – 525) = 6.9 Volts)
This exceeds the maximum volt drop, so we have to increase cable size and recalculate
For 16 mm², mV/A/m = 2.9
mV/A/m corrected for power factor = mV/A/m x Power Factor = 2.9 x 1 = 2.9
Voltdrop = (mV/A/m x Length x Design current) / 1000
Voltdrop = ( 2.9 x 70 x 30 ) / 1000
Voltdrop = 6.09 Volts
Calculated Cable size = 16 mm², Minimum Earth conductor size = 16 mm²
Maximum Cable Length = 79.3 Metres

?When laying the armoured cable, make sure you have dug at least a 50cm deep trench or can attach it to a wall or fence out of the way so it won’t get accidentally damaged. Work with its natural ‘lay’ as it comes off the reel, otherwise you may cause the internal wires to dislodge and end up having to replace the whole cable!?

cable-into-ground armoured-cable-chink

So, Solar or Mains, which is best?

Obviously it depends on what you’ll be using your shed for. But for a DIY-er, a lighting installation can be tackled easily enough. For making proper use of your shed for the majority of us amature DIY-er’s it then comes down to budget, and mains electric will almost always work out cheaper. The benefit of ?free? energy from the Solar panels will only be realised over many years of use. So to cover all bases for now and the future, we would always recommend mains electric. Happy installing!

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