A map of the fuse box

October brings the evenings in fast, with the kettle and the oven both on at once. A fuse goes, half the house is dark, and someone stands at the cabinet with a phone torch reading numbers that mean nothing.

The card

The cabinet should hold a list of circuits, the gruppförteckning, and in an older house it is often faded, out of date or gone. The fix takes one afternoon and two people. One switches circuits off one at a time while the other walks the house with a lamp, trying sockets and switches room by room. Everything that goes dark gets written down against that number, in pencil, on a card cut to fit the inside of the cabinet door.

Be specific. “Kitchen” is no help when the dishwasher and the cooker hood sit on different circuits. Note the rating printed on each fuse beside the room, since a replacement has to match it.

The tin

Spare fuses live in a small tin with a lid, labelled on top and kept on the shelf nearest the cabinet, never in a drawer with everything else. One of each rating in use goes in it, and a working torch sits beside it. Where the cabinet is in the garage, that shelf becomes part of the workshop’s own order, where fixings and power tools each keep to their own side of the bench. The same rule as the jars under the workshop shelf applies: small things only stay found if they have one place.

Where the job stops

Elsäkerhetsverket, the electrical safety authority, lists what a householder may do without an electrician. Replacing a blown screw-in fuse and resetting a tripped circuit breaker are on the list, as are changing a bulb or a lampholder. Changes to the fixed wiring are not, and nor is swapping an unearthed socket for an earthed one.

The authority’s own instructions for a blown fuse are short: unscrew the fuse cap, put in a new fuse with the same rated current, screw it back. It adds a warning worth copying onto the card. A fuse can be broken even when the little indicator bead has not dropped out of it. And a fuse that blows again has a fault behind it, and that belongs to an electrician rather than to the tin.