Fused Spur (FCU)
Switched fused connection unit feeding a fixed appliance.
● Line● Neutral● Earth
Tap any wire, switch or device to see what it is.
Useful Information
Taken from a ring or radial; the fuse protects the outgoing flex or cable.
Double-pole switched versions provide isolation.
Important to know
- Fuse to suit the appliance and outgoing cable (433.1).
- Boilers: often a 3 A fuse; follow manufacturer's instructions.
- Only one FCU per unfused spur on a ring (Appendix 15).
BS 7671:2018+A4:2026 references
433.1537.3Appendix 15
Study notes paraphrased — check against your copy of BS 7671.