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What do I need to know to wire a garden office?

Apr 19, 2022

By Vicente Romano, Managing Director, EMS Electrical
Many people find that a shed is a great place to work on DIY projects, have a dedicated space for hobbies or simply for storage. However, since these outbuildings are not connected to the mains power of the home, if you want electricity, they need to be wired on a separate circuit which extends from your house, either from the main board or from a separate one.

It might sound like a big job, but the process isn’t complicated. However, it requires a lot of attention to safety details – as should always be the case with any electrical installation.

If you are in any doubt, bringing in a trained electrician like EMS Electrical is the best option to ensure safe installation and function.

In this article, we will be exploring what you need to wire a shed and how to go about doing it.

What do you Intend to Power in the Shed?

The needs of each shed owner will vary:

  • Storage solution, an overhead light may be all that is necessary
  • Additional workspace and will spend a lot of time in here, sockets, lighting and power tools may all be things that you need
  • Gym or “caves”
  • In some cases, you may need plugs on the exterior of the shed also, for powering things such as lawnmowers, pond pumps etc.

It sounds silly to work out why you need power in your garden office/cabin/shed you named, but by doing it, you will be able to understand:

  • How many sockets you need
  • The type of lighting
  • Whether or not you need data cabling or not
  • Other aspects which will allow you to give an electrician more detailed instructions.

It may also be a good idea to install extra sockets – just in case.

Things to Consider

Whilst wiring a shed isn’t the most complicated electrical job in the world, there are some things that should be considered before work takes place.

For example, where you will run the cable. Of course, using a steel wired armoured cable under the ground is the most sensible option and this needs to end up at the shed. However, depending on your property, the cable may run in several courses. For the most part, you should be able to run the line directly from your fuse box. However, if the fuse box does not have enough circuits, a new one may be required and a qualified electrician in Reading like EMS Electrical should always carry this out. This will, of course, add to the cost of wiring the shed so it is important to budget for this when making your plans.

Additionally, it is a good idea to determine the location of the cable before calling in your electrician and marking this out on the ground. SWA cables are designed to withstand moisture and rot and so can be safely buried under the ground with no risks.

The size of the armoured cable should be taken into consideration. Speaking to your electrical contractor in Reading and surrounding areas will give you a good idea of the type of cable that you will need but in most cases between 10mm and 16mm will be sufficient, even in some case and even 6mm will be enough.

In terms of amperage, your SWA cable should run from an RCD of 32 amps which is more than enough in most cases, once again will depend what are the requirements.

Ask to your electrician or electrical contractor what will be the best.

It is clear that, unless you are qualified to undertake this type of electrical installation, doing so is not the best idea.

The main reason of not going with the DIY is your own safety – without the required knowledge, electricity can be extremely dangerous. Many people would go down the DIY route, using online forums.

Risk with DIY

If electrical circuits are not correctly installed, this could lead to the sockets becoming easily overloaded, which could result in them overheating. This can then lead to an electrical fire or injury.

Furthermore, incorrectly fitted wiring could become frayed or damaged, power surges could result and your appliances could become damaged.

It isn’t difficult to see that the risks range from a broken power tool, which is replaceable to loss of life in an electrical fire – the damage of which can never be undone.

There is no doubt that wiring a shed is a job that can be simply undertaken by a qualified electrician, and unless you have the relevant knowledge and skills, you should never go down the DIY route. This is the main thing to consider in terms of safety.

Using an RCD is essential as this eliminates the risk of shock. This device will cut off the power if there is a leakage and can be life-saving.

Adding electricity to a shed may be one of the most handy customisations you can make to this type of outbuilding. It can be especially useful for those who work in their sheds or use it as a place to enjoy a hobby.

However, wiring a shed can be a very dangerous job if the work is undertaken by someone who is not qualified so it is imperative that you employ the services of a trained electrician.

Furthermore, planning is critical and knowing how, why and where are all important in letting your electrician know exactly what you need.


Before you begin undertaking any work, it is crucial to ensure that you have everything you need – you wouldn’t want to get halfway through the job and have to down tools to run out for supplies. That being said, if you are not a qualified electrician – the safest option is to hire a professional to do the work for you.

It may surprise you to learn that you don’t need as many things as you might initially think when wiring a shed – but it is vital to keep in mind that when installing electrics, quality should be your priority.
You will need the following equipment:

  • A conduit or armoured cable – we prefer a steel wire armoured cable which will run from the main house to the shed, under the ground
  • Fuse box
  • Switches, light fittings, sockets
  • Electrical wires
  • RCD (residual current device)

Once again, if you are hiring the services of an electrician, they will likely include all of the above equipment in their price, and discuss with them your options.

Light Fittings

Most people prefer LED batten lighting in an outbuilding such as a shed.

LED lights offer a much longer lifespan, brighter illumination and, unlike fluorescent bulbs (please don’t go with fluorescent, I know it sounds biased).

If you are going to be spending long periods in your shed, it is advisable to go with the more modern LED lighting solution as this will save you money in the long run since you will not need to replace the light as frequently.

How much it will be to wire an Outdoor Building

The would vary between £1000 to £2000, but once again it will depend on the requirement and it will always be good to make a survey on site.

If you want to know more about it or for a free quote please get in touch.

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