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Fused spurs are one of those accessories most people walk past every day without noticing. They sit above kitchen worktops, beside boilers, next to bathroom doors and behind wall-mounted TVs. However, when a new appliance arrives without a plug, or an electrician says the towel rail needs "a spur", the questions start quickly.
Is a fused spur the same as an FCU? Do you need a switch? Which fuse goes in it? And what is a fused spur socket? The answers are simple once you see what the accessory actually does.
At SND Electrical, we supply switched and unswitched fused connection units in screwless metal and white plastic finishes for kitchens, utility rooms, bathrooms and plant cupboards. This guide explains the differences, where UK homes typically need one, and what to check before ordering.
A fused spur, also called a fused connection unit (FCU), connects a fixed appliance directly to the wiring through a replaceable BS 1362 cartridge fuse. Choose a switched version when the appliance needs local isolation, and an unswitched version when it should not be turned off by accident.
For most homes, a 13A double pole switched FCU covers kitchens and utility rooms, such as the Hilton 13A Fused Unit With Double Pole Switch (screwless plate, BS 1363-4, 25mm minimum box depth). For boilers, alarm panels and fans that should stay on, the Hilton 13A Fused Connection Unit is the unswitched equivalent. The Crabtree 7832/3SC Neon Switched Fused Spur adds a neon indicator in a satin chrome Platinum finish.
In UK wiring, a spur is a branch taken off an existing ring or radial circuit. A fused spur puts a cartridge fuse at the start of that branch, so the cable and appliance beyond it are protected at a lower rating than the main circuit. A typical ring final circuit is protected at 32A, while the fused spur limits its branch to 13A or less.
"Fused spur", "fuse spur", "spur unit" and "fused connection unit" all describe the same accessory. FCUs are made to BS 1363-4 and take the same BS 1362 fuses used in UK plugs.
An unfused spur is different. Taken from a ring, it is typically limited to one single or twin socket outlet, or one FCU, because it has no extra fuse protecting it. A fused spur has no such limit on outlets, but everything after it shares the fuse rating, usually 13A at most.
A switched FCU adds a double pole switch that disconnects both line and neutral. That makes it useful for isolating an integrated dishwasher, washing machine or cooker hood without pulling units apart. Our Hilton range, Crabtree Platinum 7832 and Crabtree Capital 4827 are all double pole switched versions.
An unswitched FCU has a fuse but no switch. It suits equipment that should always stay powered, such as intruder alarm panels and boilers where the installer has provided isolation elsewhere. The Crabtree Capital 4828 and Hilton unswitched FCUs in Matt Black and Antique Brass cover this.
A neon indicator shows when the circuit is live, which helps with heaters, towel rails and anything hidden from view. A flex outlet lets an appliance flex enter through the faceplate rather than a separate cable connection, which keeps installations tidy for heated towel rails and wall-mounted heaters. The Hilton 13 Amp Fused Connection Unit Switched With Neon & Flex Outlet combines both.
Cookers and electric showers are different. They normally need their own dedicated circuit with a suitably rated switch, not a 13A FCU. Immersion heaters usually use a 20A double pole switch, such as the Crabtree Capital 4015/31 printed 'Water Heater' or the Hilton 20A Double Pole Switch With Neon.
"Fused spur socket" is a common search, but it can mean two different things. Most often, it describes a socket outlet fed through a switched fused spur, for example a single socket behind an integrated dishwasher, controlled by an FCU above the worktop. The appliance can still use its normal plug, while the FCU provides accessible isolation and extra fuse protection.
It can also mean a single plate combining a socket and a fused unit. We do not currently list a combined socket and FCU plate, so for that layout we would suggest a matching FCU and socket from the same range. Our switches and sockets collection and the Hilton range make that easy to match.
Remember that anything fed through the FCU shares its fuse. A twin socket fed from a 13A fused spur cannot supply two 3kW appliances at once.
The fuse should suit the appliance and the cable after the FCU. Always follow the manufacturer's instructions first. As a general guide:
| Fuse | Typical load | Common examples |
|---|---|---|
| 3A | Up to about 700W | Extractor fans, boiler controls, LED drivers, alarm panels |
| 5A | Where a manufacturer specifies it | Some heating controls and small heaters |
| 13A | About 700W to 3kW | Washing machines, dishwashers, tumble dryers, panel heaters |
Fitting a 13A fuse "to be safe" is a common mistake. A lower-rated fuse protects a lighter flex or low-power appliance properly, and it is usually the rating the manufacturer asks for.
An FCU usually sits at eye level above a worktop or beside a door, so it is more visible than most sockets. Matching the finish to the room's switches and sockets matters.
Our Hilton screwless FCUs come in Brush Chrome, Matt Black and Antique Brass, all with a black insert, and fit a 25mm minimum back box. The Crabtree Platinum 7832 range offers satin chrome, highly polished chrome, black nickel and brass, with a 35mm installation box depth listed for the neon versions. For practical spaces, Crabtree Capital 4827 and 4828 are white moulded options.
Check the box before ordering. Our wiring accessories include the SND 25mm 1 gang metal back box and 35mm dry lining boxes. For more on plate styles and finishes, see our switches and sockets buying guide.
Swapping a faceplate like for like is generally not notifiable in England. Adding a fused spur to an existing circuit outside a special location is also usually not notifiable, but it must still meet BS 7671. That includes correct cable sizing, RCD protection where required, and safe zones for concealed cables.
Under Approved Document P, new circuits, consumer unit replacements and work in the special location around a bath or shower are notifiable. A competent, registered electrician can carry out and self-certify this work, and should check that the existing circuit can take the extra load. Our guide to when to replace old sockets and switches and Part P basics explains the differences in more detail.
If you are unsure whether a spur is legal, safe or suitable for the load, stop and ask a qualified electrician. Always isolate the circuit at the consumer unit and prove it dead before removing any accessory.
Most of these are avoided by deciding what the spur supplies before choosing the plate.
Before ordering a fused spur, confirm:
There is no practical difference. "Fused spur" is the everyday name, while "fused connection unit" or FCU is the trade and product name for the same accessory.
Choose switched when the appliance needs local isolation, such as an integrated dishwasher. Choose unswitched where it should stay on, such as an alarm panel or some boiler installations.
Use the rating the appliance manufacturer specifies. As a general guide, 3A suits loads up to about 700W, and 13A suits about 700W to 3kW.
Yes. A socket fed through a fused spur is common behind integrated appliances. Everything plugged into it shares the FCU's fuse, usually 13A.
Usually, yes. A switched FCU with flex outlet is common, installed outside the bathroom zones. Bathroom electrical work in England may be notifiable, so use a registered electrician.
The Hilton 13 Amp Fused Connection Unit Switched With Neon & Flex Outlet in Brush Chrome, and the Hilton 13A DP Switched Screwless FCU with Neon & Flex Outlet in Antique Brass, both include a neon and flex outlet.
Only if the manufacturer states it is suitable for a 13A supply. Most cookers and many larger ovens need a dedicated circuit with a cooker switch.
A fused spur is a small accessory, but the right one makes an appliance safer to use and easier to maintain. Decide what it supplies, choose switched or unswitched, fit the correct fuse, then match the finish to the room.
At SND Electrical, we look at the whole room first. Which appliances are fixed? What needs isolating? Which plates are already on the wall? Answering those questions before ordering leads to a kitchen, bathroom or utility room where every spur makes sense.