Free notes
Fuses and ratingsWhich fuse protects only the appliance's flex?
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- BS 1362
- The plug-top fuse (3 A or 13 A etc.). It only protects the appliance's flex, not the appliance or the fixed wiring.
- BS 88-2
- Bolted cartridge fuses, used in larger commercial and industrial installations.
- BS 88-3
- Cartridge fuses that replaced BS 1361 (around 2010), e.g. the DNO cut-out fuse.
- BS 3036
- Rewireable fuses in old consumer units.
| Colour | Fuse | CB (type B) |
|---|---|---|
| White | 5 A | 6 A |
| Blue | 15 A | 16 A |
| Yellow | 20 A | 20 A |
| Red | 30 A | 32 A |
| Orange | 40 A | 40 A |
| Green | 45 A | – |
Typical domestic circuits: 2 lighting (upstairs and downstairs), 2 socket circuits, cooker, shower, immersion heater, maybe a separate kitchen circuit. Smoke alarms are often taken off a lighting circuit. How many you can fit depends on the number of ways in the board, and RCDs take up ways too.
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