Fuses and my beffudlement...

[jmurray01]

I'm very confused about what fuse amperages I should use in what wattage vacuum motors, because I've read about start up surges causing the fuses to blow if too low.

My main question is; is it safe to rely on the old fashioned rule of 3AMP for under 700W and 13AMP for over 700W if your house has an RCD fitted ?

If not, I'm going to be thoroughly confused come the day I have to work out what fuses to replace and with what...

Oh my, I'm befuddled!

 

[vintagerepairer]

Jamie, the fuse is there to protect the mains lead, so if there is a short then the fuse blows rather than the lead catching fire. The wattage is a guideline as flexes are sized according to wattage and the rated-on time (the time the appliance is used at full power) because a thicker flex -whilst perfectly safe- would be too expensive and too bulky for a good deal of appliances. However, for a long time the 13amp fuse has been recommended for so many appliances, irrespective of the size of lead. I assume this is because of modern RCD consumer units and because so few other countries have plug fuses anyway.

For supreme safety, you can just fit the lowest possible fuse. Most motors up to 550watts will be fine with a 3amp fuse, indeed the Hoover Turbomaster instructions used to recommend a 3amp and they ran at about 575 watts. A 5 amp fuse will do for many cleaners up to 1000 watts, but I know some like Dyson at 1200 which work and some less than 1000 like Henry which can blow on start-up. It's all about how much current is pulled on start up.