Really dumb question!!

[pdcelec]

Sometimes the amps are not marked on an applience, because they can be calculated.

Power (watts) = I (amps) x v (volts)

If you rearange this you can see that I(amps) can be worked out by power (watts) divided by volts

Power is a measure of transfer of energy (one watt = one joule a second)
Current is a measure of flow of charge (one amp = one coulumb per second)
Voltage is a measure of energy per coulumb (one volt = one joule per coulumb)

If you look at the above definations and at the P=IV equation, it might help you to understand it a bit better

Hope this is helpful

Adam

Although this is not quite true with an ac circuit.

Power = VI cos phi

Power = Volts X amps x power factor

where power factor is about 0.85 for an inductive circuit (the norm for most equipment)

Power = 230 X amps x 0.85 (roughly)

Hope this is of some benefit

 

[plugwash]

it depends on what the equipment is

most high power equipment in homes is purely resistive stuff so power factor (cos phi) is 1

electronic equipment and flourescent lighting may have a much lower power factor though especially if its old or imported from outside the EU and not CE marked.

 

[dunny]

Thanks. Out of interest I am going to look at what I typically have on the ring. I dont have any problems with tripping or anything but just interested. Feels like all laymen (i.e. the likes of me) should have basic understanding of this stuff.

An example of why occured just today at my brothers house. He has an outside light and pond pump and he asked me to replace the fuse in the plug. I opened the plug and it had a 13amp fuse in it. This didnt seem right so I asked whether he knew what fuse it should be, of course he never and no longer had the handbook. He said its been working for years with a 13amp so it must be OK. I didnt know how to work out what its should be fused at so I looked on the net, found his model and found it should have been fused at 3amp!!

 

[Agile]

At this rate he will be getting an NVQ 1 shortly.

Tony