FUSE RATINGS IN PLUG TOPS
All electrical items in the home should have a plug top fitted with the appropriate fuse rating, the load (amps) of electrical equipment and appliances can be calculated thus :-
WATTS ÷ VOLTS = AMPS
1 KILOWATT = 1000 WATTS VOLTS = 240v
So if you have a 240 volt heater rated at 3 KW (3000 watts) it will have a load of 12·5 amps, therefore it requires a fuse rated at 13 amps.
Fuses rated at 3, 5 and 13 amps are easily purchased from most DIY stores, fuses rated at 2 and 10 amp are more difficult to purchase unless you go to an electrical wholesalers.
The problem in most homes is that if a replacement plug top is fitted to an electrical item it will more than likely be fitted with a 13 amp fuse, regardless of what the wattage is.
The one item in the house that is usually fused incorrectly is the table / bedside lamp, it probably has a lamp of no more than 60 watts so has a load of 0·25 amps and could be fitted with a 13 amp fuse, if the lamp develops a fault there’s a good chance the cable will melt before the fuse blows and could even cause an electrical fire. So fit the lowest rated fuse available either 2 or 3 amp.
- Fit a fuse that is rated correctly for the electrical item it is protecting.
- Kettle 13 amp
- Table lamp 3 amp
- Hi-fi system 5 amp
- 3 kw heater 13 amp, 2 kw heater 10 amp
- Radio 2 or 3 amp
- 500 watt - 3 amp,1kw - 5 amp, 2 kw - 10 amp, 3 kw - 13 amp
Fortunately the majority of household electrical items bought today are fitted with a moulded plug and the correct rated fuse, but it is worth having a selection of different rated fuses at home, then at least when they need replacing you have a suitable fuse available.
Always check connections are correct and tight if you have to replace a plug top. (see how to fit a plug top post ).
The following are colours used to identify conductors in a 3 core flex.
- BROWN = LIVE
- BLUE = NEUTRAL
- GREEN/YELLOW = EARTH