How to calculate the Amps if I only know the volts & watts?

[mart]

I was initially thinking that Ohm's law would help me Is there another formula ?

 

[hotponyshoes]

Watts divided by volts

 

[daedalusminos]

V=IR
P=IV

 

[daleyd]

Amps = Power/Volts

 

[wyn]

W = V x I

 

[premmington]

Watts divided by volts

+1 for the above.

 

[mart]

Watts divided by volts

10W ÷ 240V = 0.0416666667 Amp
So a 5amp rated flex will be plenty.

 

[hotponyshoes]

10W ÷ 240V = 0.0416666667 Amp
So a 5amp rated flex will be plenty.

Yea,
Or 41 miliamps (as its probably easier to find a 50ma fuse than a 0.05 amp one..)

 

[Barking Mat]

What are you doing ? / Installing ?

 

[hotponyshoes]

Doesn't apply in this case as you have loads of headroom but for calculations nearer to the limit of the cable bear in mind that mains voltage (at least in my house) can regularly drop to 220v or so

 

[mart]

Yea,
Or 41 miliamps (as its probably easier to find a 50ma fuse than a 0.05 amp one..)

The smallest fuse I have for my plug is a 3amp

 

[hotponyshoes]

The smallest fuse I have for my plug is a 3amp

Thats fine.
Basically the 3a fuse should blow before the 5a cable catches fire

The fuse probably won't protect the 10w device on the end though..

 

[mart]

What are you doing ? / Installing ?

I have a 3 core flex with a bulb holder on the end with a 10w LED GU10 fitting. Nice and bright above my head for reading?

 

[hotponyshoes]

The cobwebs on the roof are probably more of a combustion hazard.
Has that chair got a fire label on it?

 

[hotponyshoes]

I have a 3 core flex with a bulb holder on the end with a 10w LED GU10 fitting. Nice and bright above my head for reading?
View attachment 422734View attachment 422735View attachment 422735

That should be ok,
I had a normal 6-bulb unit in my kitchen and I replaced the bulbs in that with gu10 led.
Although the bulbs blow fairly regularly tripping out the rcd. They go off with quite a loud pop and occasionally blow the glass bit across the room.
They most often seem to go when first switched on so I think if I had one above my head I might put the switch somewhere that I couldn't turn it in when I was sat underneath it..

 

[Screwdriver]

I have a 3 core flex with a bulb holder on the end with a 10w LED GU10 fitting. Nice and bright above my head for reading?
View attachment 422734View attachment 422735View attachment 422735

Jesus! That looks like the set from a horror movie!

 

[daedalusminos]

Jesus! That looks like the set from a horror movie!

 

[mart]

That should be ok,
I had a normal 6-bulb unit in my kitchen and I replaced the bulbs in that with gu10 led.
Although the bulbs blow fairly regularly tripping out the rcd. They go off with quite a loud pop and occasionally blow the glass bit across the room.
They most often seem to go when first switched on so I think if I had one above my head I might put the switch somewhere that I couldn't turn it in when I was sat underneath it..

What was the wattage of the LED bulbs?