A fused connection unit — often called a fuse spur or FCU — is a fixed electrical connection point that provides a direct, permanent connection to the mains supply for an appliance. Unlike a socket, you don't plug into it — instead, the appliance cable is wired directly in.
When Is a Fuse Spur Used?
Fuse spurs are used for appliances that:
- Are permanently connected rather than plugged in and unplugged regularly
- Benefit from a local isolating switch (so they can be turned off at the wall without unplugging)
- Require a fused connection for protection
Common applications include:
- Boilers and heating systems — almost always connected via a switched fuse spur
- Extractor fans — typically wired to a switched or unswitched fused spur
- Dishwashers and washing machines — many are wired to fused spurs rather than sockets
- Electric towel rails and bathroom heaters — fused spur with double-pole switch
- Garden pond pumps — external weatherproof fused spurs
- Doorbells and intercoms — transformer connected via fused spur
Switched vs Unswitched
Switched — has a rocker switch on the front, allowing you to turn the appliance on and off at the unit. The switch can be single-pole (switches the live only) or double-pole (switches both live and neutral — preferred for complete isolation).
Unswitched — permanently live; the appliance can only be isolated at the consumer unit.
What Fuse Rating?
Standard fuse spurs use 3A or 13A fuses. For most appliances, a 3A fuse is appropriate — for example, boilers, fans and doorbells. For appliances drawing higher current, a 13A fuse is used.
Do I Need a Fuse Spur or a Socket?
If you want the flexibility to unplug and move an appliance, a socket is correct. If the appliance is permanently installed and won't be moved, a fused connection unit is the professional solution — it looks neater and provides direct protection for that circuit.
Onyx Electrical Solutions installs fused spurs across Greater Manchester. Call 07000 000000 for a free quote.