Does watts stated on an appliance mean MAX it will use.

[mart]

I am using a fan that has several speeds as well as the swivel action.

On the base it states 400W. I would have guessed at more than 400w if used on highest speed & in swivel mode.

I am more concerned at having the correct fuse in the plug 2amps or 3amps? Don't want any fires as it will be in my outhouse and out of sight for 2 or 3 hrs drying the concrete floor nearby.

 

[bigegg]

Maximum

 

[brightspark]

stick a 3amp in

 

[wookie]

Watts = Amps x Volts, so 400W would be okay on a 2A fuse but you're more likely to have a 3A fuse lying around so use that as @brightspark suggested.

Just don't do what I see all the time where people just use a 13A for everything "because it saves them blowing...."

 

[evobilly666]

Remember, a BS1363 plug top fuse is there to protect the flex, not the appliance so what size is the flex?

 

[tlovatt]

Watts = Amps x Volts

Err no it does not,

Watts = Amps x Volts x Power Factor

If you are looking at a heater then the power factor will be almost at unity and so can be ignored, but for a fan motor it will probably be closer to 0.8 (possibly lower if the manufacturer fitted an oversized motor) so needs to be taken into account as the motor will not draw the current in phase with the voltage mainly due to its inductance.

 

[Matrixx]

As said above the fuse is there only to protect the cable. Nothing else. All it sees is amps , not reactive current.

 

[brightspark]

Remember, a BS1363 plug top fuse is there to protect the flex, not the appliance so what size is the flex?

probably .75mm

 

[wookie]

Err no it does not,

Watts = Amps x Volts x Power Factor

If you are looking at a heater then the power factor will be almost at unity and so can be ignored, but for a fan motor it will probably be closer to 0.8 (possibly lower if the manufacturer fitted an oversized motor) so needs to be taken into account as the motor will not draw the current in phase with the voltage mainly due to its inductance.

I know but I was trying to keep it fairly simple, perhaps anything other than a purely resistive load should by law also have to list it's VA rating and PF as well as Watts and Volts.

Ignoring PF for a minute makes the maths nice and simple so I can do it in my head, so I work out I need a 2A fuse for my fan, now if the PF means it actually draws more current then the worst that will happen is the fuse blows, after all the fuse is there primarily to protect the cable, so no harm done.

 

[Matrixx]

Yes 2A would do.
You would not normally consider power factor on a domestic installation.