A garden studio feels like a luxury until the first cold morning when you realise the only socket is behind the door, the heater needs a different corner, and there is a laptop charger stretching across the floor like a tripwire. Almost every regret people have about their garden room comes down to the same mistake: the electrics were designed after the shell was built, not before. Sort the sockets and cabling on paper first and the rest of the project becomes far calmer.

Start with the furniture, not the cable

Before anyone lifts a spade, draw a simple plan of the room to scale and place everything that will ever need power. Walk through a typical working day in your head and mark each item where it will actually sit.

• Desk position: which wall, which side, and whether you face a window or a view.
• Desk equipment: monitor, laptop, dock, printer, desk lamp, phone charger, router.
• Heating: a 2kW oil-filled radiator, an infrared panel, or an air source heat pump. Each one changes the electrical demand dramatically.
• Comfort and convenience: kettle, coffee machine, small fridge, fan, dehumidifier, vacuum charging dock.
• Hobbies: sewing machine, soldering iron, pottery wheel, amplifier, projector, record player.
• Outdoors: a socket for the mower, a light by the door, a camera or security light.

Once the plan is marked up, count the sockets you think you need and add at least half again. Empty sockets cost very little at first fix and are deeply annoying to add later.

Work out the load before you choose the cable

A garden studio usually gets a single supply from the house, and its size decides everything else. A modest office with a laptop, lights and a 1kW heater will comfortably run on a 16A supply. Add a 3kW heater, a kettle and a small fridge and you are pushing towards a 32A supply with a small consumer unit in the studio.

Ask your electrician to calculate the total demand properly, including diversity — the sensible assumption that not everything runs at once. They will also check the volt drop over the cable run. A long cable to the bottom of the garden loses voltage, so a run of 30 metres may need a larger conductor than the same load at 10 metres. Getting this wrong shows up as flickering lights and a heater that never quite performs.

Plan the trench, duct and cable route

The trench is the one part of the job you never want to repeat. Dig it once, generously, and leave yourself options.

• Depth: bury armoured cable at around 600mm, deeper under a driveway or where vehicles cross.
• Bedding: a layer of sand below and above the cable, then a marker tape so a future spade strikes plastic before it strikes power.
• Ducting: run a 50mm duct alongside the main cable with a draw cord inside. That empty duct is how you add Ethernet, an alarm cable or a second circuit in five years without digging again.
• Route: keep away from drainage runs, tree roots and the line of any future patio or shed base.
• Entry: bring the cable up into the studio through a sealed gland, not a hole stuffed with foam.

Steel wire armoured cable is the standard choice for buried runs, and it must be properly glanded and earthed at both ends. Where the house supply uses a PME earthing arrangement, your electrician may need to install a separate earth electrode at the studio rather than exporting the house earth. This is a detail worth discussing early, because it affects the trench and the consumer unit.

Position sockets where the furniture will hide them

Interior socket heights are a matter of taste, but a few rules save a lot of clutter.

• Fit double sockets above desk height, or just below the worktop so cables drop neatly behind the furniture.
• Put a socket on each wall, even the one you think will stay empty.
• Include USB or USB-C charging points at the desk so plug-in adapters do not hog the sockets.
• Use a floor socket only if you are certain of the layout — they are awkward to move and easy to cover with a rug.
• Keep heater sockets on their own circuit where possible, so a 3kW appliance never shares a spur with sensitive electronics.
• Add a switched fused spur for any fixed heater or extractor fan, with the isolator within easy reach.

Lighting deserves its own thought. Split ceiling lights and task lighting across two switches so you can work under bright light in the evening without floodlighting the whole garden. If you plan to record audio or video, put lights and power on separate circuits to reduce hum and flicker.

Data, ventilation and future-proofing

Wi-Fi rarely reaches the end of a garden well, so run at least two Cat6 cables through that duct while the trench is open — one for the router or access point, one spare. If you use a mesh system, the studio node still performs far better with a wired backhaul.

Think about ventilation and cooling now too. A heat recovery unit or extractor fan needs a power feed, and a small air conditioning unit may need its own supply. Add an outside weatherproof socket near the door for tools and a light, and consider a small outdoor-rated isolator so you can shut the studio down safely when you are away.

Finally, insist on proper certification. In the UK, most garden studio supplies are notifiable work, and you should receive an Electrical Installation Certificate plus building regulations compliance. Test the sockets, check the RCBO trips, and label the consumer unit clearly. Do that once, at the start, and your garden studio will quietly support everything you throw at it for years.