Can a 250v kettle cable power a 230v power supply?

redped

You won't be able to work out which fuse is right until you know what current the PSU draws - that is usually marked on it somewhere. If it's a desktop, then there may be a label on the PSU inside the computer that says this. Is there a wattage figure mentioned? The number of watts used is equal to the voltage multiplied by the current (good old Ohm's Law, P = V * I), so if you know the wattage then you can work out the current, and hence the correct fuse rating.

m5rcc

I think it is 10A from what it says on here, however the cable it used to work before (and for many years) was 5A.

esuhl

redped wrote: »

The number of watts used is equal to the voltage multiplied by the current (good old Ohm's Law, P = V * I), so if you know the wattage then you can work out the current, and hence the correct fuse rating.

So, to do the maths for you, with a nominal 230V AC mains supply...

A plug with a 3A fuse wouldn't blow until it draws ~690W of power.
A plug with a 5A fuse wouldn't blow until it draws ~1150W of power.
A plug with a 10A fuse wouldn't blow until it draws ~2300W of power.

In reality mains voltages can fluctuate a fair bit, so it makes sense to leave a bit of "headroom" - e.g. if an appliance is rated at 670W, it would probably be appropriate to use a 5A fuse to allow for such fluctuations.

victor2

redped wrote: »

At a guess, I'd say the fuses in the three cables are blown (probably by trying them all on the PC with the dodgy PSU), and you'll need to replace them. After replacing them, try them all on something other than your dodgy PSU, as that'll just blow them again.

Bear in mind that fuses only blow when there's a problem with the equipment it's protecting, so you'll also need to replace your PSU.

I'd agree with that.
Ignore your dodgy computer for now and sort out replacing the fuses in the power cables which you have blown. If you get all cables operational and have a spare fuse left, try just one on the faulty computer if you want to verify that it is blowing the fuse.

You'll probably need someone comfortable with working on mains powered devices to look at the computer. If the PSU has failed, then replacing one usually isn't too difficult, but does involve disconnecting the power leads from the PSU to the motherboard and all other powered devices in the computer. Could be a job for your local PC repair shop.

m5rcc

Just bought some 13A fuses and replaced the old 10A cable with it. Works fine with the new PC.

Gonna try the others in a sec.....

m5rcc

Works with my monitor but doesn't work with my old PC - so I think I was aright to assume the PSU has gone on that one.

redped

Sounds like you're making good progress, all you need now is a new PSU for the old PC. As victor2 says, if you're not comfortable working with mains electricity (never forget that it can kill, especially if you're not sure what you're doing) then get a couple of quotes from PC repair shops and get them to fit a new PSU.

macman

Replacing a PSU does not involve working with a mains supply, it is a straightforward disconnection and reconnection of an identically or higher rated component while entirely isolated from the mains supply. If you can use a screwdriver and take the side panel off a PC, then you can change the PSU.

redped

I meant that the consequences of incorrectly wiring up a PSU could be lethal, rather than frying yourself while actually changing it. While you and I may be happy to change a PSU, not everybody is as confident when working with electrical devices.

macman

I don't see how it could be lethal, since a PSU is only outputting 12V. No wiring or connection is required on the 240V side.