Shed, Studio or Small Power Station? A Sensible Electrical Audit for Your Garden Office

A garden office has a way of starting out as a shed with pretensions and ending up as a small power station at the bottom of the lawn. First it is a desk and a laptop. Then it is a heater, a kettle, a monitor, a printer, a dehumidifier and a Wi-Fi extender that never quite works. By the time January arrives, the extension lead is doing something no extension lead should ever do.

So before you buy the insulated pod or convert the old shed, it is worth running a proper power audit. Not because garden offices are dangerous by nature, but because the electrical supply is often an afterthought. Here is how to think it through.

First, call it what it is

A garden office is a dwelling-adjacent workspace. It has insulation, a door that closes properly, a heater that runs for hours and probably a kettle. That makes it different from a shed that stores the mower. If someone is spending whole days out there, the electrical installation needs to behave like a small room, not an outdoor socket with a long flex.

That means fixed wiring, proper protection and a supply that can carry the load without warming up. It also means thinking about how the cable gets from the house to the garden room, because that route is where a lot of cheap jobs go wrong.

Add up the real load

The temptation is to count the laptop and the lamp and call it 500 watts. The reality is usually bigger. A 2kW panel heater alone is nearly 9 amps. Add a 3kW kettle and you are at 22 amps if they run together. A small air fryer or microwave, a monitor, a printer, lights and a dehumidifier all add up. None of them is huge on its own. Together they explain why a 13-amp extension lead from the house is not a serious answer.

Write down everything that will be plugged in, then add the things you will probably buy later. If the garden office is going to be used year-round, assume heating will run for long periods. That is the load that matters most.

Extension leads are not distribution circuits

A daisy-chained extension lead running down the garden is a bad idea for several reasons. It is vulnerable to damp and damage. It creates a trip hazard. It usually has no RCD protection at the far end. And it encourages people to plug a 2kW heater into a lead that was designed for a strimmer charger.

If the garden office needs power, it needs a fixed supply. That usually means a suitably sized armoured cable buried or clipped along a sensible route, with mechanical protection where needed and a proper termination at both ends. Steel wire armoured cable, often called SWA, is the usual choice for buried supplies because it is tough and has an earthed armour. It still needs to be installed correctly, with the right glands and earthing arrangements.

The garden consumer unit

A separate consumer unit in the garden room is often the cleanest solution. It gives you local isolation and separate protective devices for lights, sockets and heating. That matters when a fault trips something at 9pm and you do not want to walk back to the house in the rain to reset it.

RCD protection is essential. In many garden office installations the supply is taken from the house consumer unit, and the protective device there needs to be coordinated with the garden unit. You do not want two RCDs fighting each other or a fault that cannot be isolated locally. An electrician will also check the house supply capacity, the earthing system and the voltage drop over the cable run. A long run to the bottom of the garden can make a difference to cable size.

Heating is the decision that drives everything

A 2kW convector heater is cheap to buy and expensive to run. An infrared panel heats people rather than air, which can suit a small office. An oil-filled radiator is slow but steady. A small air-source heat pump is more efficient but costs more upfront and needs a properly sized supply. Underfloor heating is lovely and usually needs to be planned before the floor goes down.

Whatever you choose, do not plug it into an extension lead. A fixed heater should have a fixed supply or a dedicated socket on a circuit that can carry it. If you are heating a garden office through winter, the heating load is the one to design around.

Data and Wi-Fi deserve their own thought

Power is only half the job. If the garden office is more than a few metres from the router, Wi-Fi will be patchy. The reliable answer is a buried Cat6 cable in conduit, or a fibre run if the distance is long, terminating in a proper network socket. That gives you a wired connection for video calls and a backhaul for a Wi-Fi access point. It is much better than a repeater stuck in a window.

Run data cable separately from power cable where you can, and leave a draw cord in the conduit for future upgrades. It is a small cost during the dig and a large favour to your future self.

Part P, paperwork and the qualified electrician question

In England and Wales, many garden office jobs involving a new circuit from the house or a new consumer unit are notifiable under Part P. Scotland has its own building warrant rules, and Northern Ireland has separate building regulations. The practical point is simple: ask before work starts. A registered electrician will know what needs notifying and will provide the test certificates when the job is done.

This is not the place for a friend who is good with wires. Garden office supplies involve earthing, cable sizing, voltage drop and outdoor protection. Get someone who can test it and certify it.

A quick audit checklist

• List every appliance and its wattage, including the heater.
• Decide how the garden office will be heated before sizing the supply.
• Choose a cable route that avoids damage, ponding water and future digging.
• Check the house consumer unit for spare capacity and RCD protection.
• Plan a local consumer unit with separate circuits for sockets, lights and heating.
• Include data cabling and a draw cord in the trench.
• Ask about Part P notification and the test certificate before you book.

The realistic verdict

If the garden office is a summer-only desk, a well-protected outdoor socket might just about do. If it is a year-round workspace with a heater, a kettle and a video call habit, treat it like a small room. That means a proper supply, local protection and a cable route that will still be sensible in ten years. JEGS Electrical would rather audit it now than untangle it later.