Garage with no power: your options, from extension lead to proper supply

The extension lead: what most people do, and where it stops being sensible

A detached garage with no supply usually ends up with a lead through the kitchen window. For a drill and a work light on a Saturday afternoon that is fine, and pretending otherwise would be dishonest. It stops being fine when it becomes permanent, when the load goes up, or when it gets wet. A lead that lives under the garage door gets crushed by the door and driven over by the car; a lead across the lawn meets the mower; a lead in the rain is a risk to the person holding it.

If you do it, do it properly. An outdoor-rated lead, not a household one. Plugged into the house through a plug-in RCD adaptor, so a damaged cable trips the supply instead of hurting someone. If it is a cable reel, fully unwound every time, because a coiled reel under a heater's load heats up inside the coil and can melt. Nothing high-load for long: a fan heater, a compressor or a table saw are all reasons the arrangement is temporary.

And it is temporary. A lead is not a supply. It cannot be left in place, it cannot be relied on in winter, and it cannot be extended into a second lead and a four-way block without becoming the kind of thing that starts a fire. The honest description of the extension lead is a way to find out whether you use the garage enough to justify the real fix.

Cordless everything, and the honest limit of it

Cordless tools have made the powerless garage far more usable than it was. A drill, an impact driver, a circular saw, a grinder, a jigsaw and a multitool on one battery platform cover most of what a domestic garage ever does. Rechargeable LED work lights are bright enough for a bench and run for an evening. Charge everything in the house overnight and carry it out in the morning.

The limit is anything that draws hard for a long time. A compressor, a welder, a bench saw running through sheet material, a heater of any kind: those want mains. So does the charger itself, which is why the house is the charger and the garage has a shelf for the batteries. A rack that holds the tools with a shelf for the batteries underneath keeps the lot together, and in a garage with no power it sits by the door, on the route in from the house.

Batteries do not like the cold either. Keep them in the house through winter, bring out what you need for the day, and take them back in. A battery left on a cold garage shelf loses charge, charges badly and does not last as many years as one kept warm. A rack by the door with a shelf for them makes the habit easy: the tools stay in the garage, the batteries come and go with you.

Lighting without mains

Light is the thing a powerless garage most often lacks, and it is the easiest to solve without a supply. The table sets out the options as they actually behave in a UK winter, when the days are short and the sun is weak, rather than as the packaging shows them. Nothing here is a substitute for a wired light; all of it is better than a torch in your teeth.

A solar shed-light kit, a panel on the roof feeding a small battery and an LED inside, is the most convincing of these in summer and the least in winter, when a week of grey days leaves it with very little in the tank. Treat it as a way to find things rather than a way to work. If the garage is used for real work in the evenings, a rechargeable work light, or two, charged in the house is the practical answer until there is a supply.

Solar and battery: what to expect

Portable power stations, a battery in a box with an inverter and sockets on the front, have become popular for exactly this situation. Charged in the house, one will run lights and a battery charger for a session and charge a phone many times over. What it will not do is run a heater, a compressor or anything else that draws hard, for long. Check the continuous output against the tool you actually own before buying, and treat any run time printed on the box as a best case.

A solar panel on the garage roof feeding a battery can keep lights and a small load going through the lighter half of the year. In a UK winter the panel does little for weeks at a time, and the system that seemed generous in June is flat by Christmas. It is a genuine option for lighting and charging in a garage you cannot get a supply to, and the wrong option if what you actually want is to run a workshop. Sizing it is a subject of its own, and anyone selling you one should do it from your loads, not from a brochure.

A proper supply: what the electrician does, and why it is not you

The only real fix for a garage with no power is a permanent supply, and it is an electrician's job. Running a new circuit from the house to an outbuilding is notifiable work in England and Wales, which means it has to be done or certified by someone registered to do it and reported to building control; Scotland and Northern Ireland have their own arrangements. It is not a grey area, and it is not a job this guide will describe.

What the electrician will typically do is take a supply from the house consumer unit, run an armoured cable to the garage, either buried in a trench at a proper depth or fixed at height, and fit a small consumer unit in the garage with its own protection, then test and certify it. The earthing arrangement for an outbuilding is one of the points that needs a professional judgement rather than a rule of thumb, which is a fair illustration of why the whole job does.

What you can do is make it cheaper and better. Decide before they visit where you want sockets, lights and any high-load point such as a compressor or a car charger, because moving them later costs more than adding them now. Ask whether you can dig the trench yourself; many electricians are happy for you to, on their route and to their depth. Clear the wall where the consumer unit and the cable will go. A well-planned visit is a shorter visit.