My PC has now blown 3 13A fuses in total (each in the power strip the PC was plugged into) and I've been told that a voltage stabiliser would help. I'm just wondering if they always solve the problem and I want to check that the information I've been given on how to choose the correct voltage stabiliser spec. is correct. Also, is it ok to just keep blowing fuses every so often and not even bother with surge protection?

I've been told that the way to calculate the voltage stabiliser I'd need is to divide the PC's power by 0.6, which would be 500/0.6= 833.33... VA.

I've also been told that by one person tha there is no way that a fuse should've blown, as 500w / 230v = 2.2A and I've been using 13A fuses. As such., he suggested I have the PC checked out. The PC stopped working after I accidentally disconnected a wire/some wires inside, so I took it in to a PC repair shop. The guy in the shop fixed it and old me tha the hard drive had become corrupted. He did ask me if I'd considered surge protection and said that power surges can be a problem, without my even mentioning that a fuse had blown (only 1 had blown at that stage).

  • 1
    Related: Is surge protection actually needed?
    – gronostaj
    Aug 4, 2014 at 10:30
  • At any point have you replaced the power supply?
    – Ramhound
    Aug 4, 2014 at 10:48
  • What else is plugged into the power strip? Is the power strip also a surge protector? Aug 4, 2014 at 10:53
  • 2
    If you're blowing 13A fuses in a power strip I'd suspect that there's something wrong with your computer. Aug 4, 2014 at 11:49
  • 1
    Let’s not forget about the inrush current.
    – Daniel B
    Aug 4, 2014 at 11:55

3 Answers 3


Are you in the mainland UK? If you are I would not expect you to experience power surges that could have this effect. I think its unlikely that a surge protector would help this problem.

Its more likely to be a fault in the Power Lead, the power strip or the computer power supply. If the fuse is blowing during use its more likely to be the power lead or the adaptor, if the fuse is blowing when you turn on or plug in the computer its most likely the power supply.

Any decent surge protector would be expensive and probably fail to fix the problem.

First inspect the power lead (if its not a moulded plug check inside that the wiring is secure and tidy. Inspect the power strip, its lead and plug to ensure that there's no apparent damage.

If there is no obvious sign of a fault I would be inclined to replace the power supply unit in the PC and use a new power lead.

Continuing to use the PC with the power dropping out will most likely damage the data on the hard disk. Windows and NTFS are not robust at dealing with unexpected power outages.

  • I'm am in the mainland UK, yes. Thanks for the info. (+1). Aug 4, 2014 at 13:27

If you're in the UK, have you put the computer through PAT? It's recommended for machines more than a year old. That should find many obvious problems. I'd count it as an obvious problem if a device that should use no more than a couple of amps, unexpectedly uses more than 13 amps. That's not normal.

There may be problems in the socket bank (I had one that had a spring that should have supported internal conductors, but the spring corroded, broke and the bits jingled around inside, sometimes shorting - and blew two fuses before I tracked down the cause). Sometimes the flying lead between the socket bank and the computer has problems - usually in the plug at the either end, but sometimes because pets or pests have chewed the leads. Sometimes, the power supply unit in the PC is the problem - I've found paperclips, used staples, stray pieces of wirewool, and pen parts inside power supplies. When these are near the high voltage side, even small motions or vibrations can create a short circuit triggering a blown fuse or circuit breaker. Those problems wouldn't be found when using normal testing - because the cause is something loose and you'd need to move the equipment or have vibration cause movement, that triggers the shorting.

However, if I had a computer that blew fuses, I'd stop using it, ASAP, and start looking for a cause in the path between the input to the socket bank and the transformer in the power supply unit. This is not safe. Seriously. Find the problem. Surge protection is not the solution. Something is shorting, that shouldn't be.

  • Ok, thanks. I am in the UK and no, I haven't put it through PAT. I should say that when the fuses have blown, I think I'm right in saying I've been using the PC for quite long periods over dyas or even weeks (I have switched itt off when I've finished using it each day). It's not like the fuse blows within seconds of switching the PC on and I have been playing a game which results in the CPU temp rising to around 48C. (+1). Aug 4, 2014 at 13:25
  • You shouldn't be using more than 3 kilowatts (240VAC at 13 Amps - that's close to a kitchen kettle for heat production). The power supply is probably rated for a max of 500W (unless you have something a bit more unusual and power hungry, and even then is probably under 700W). That's about 3 amps. Not 13. To quadruple the current, or more, something is misbehaving. If it is heat, then your PSU may be overheating, or the fans are inadequate - I'd be looking at those, and still looking for issues in the chain of connection from socket bank to transformer.
    – JezC
    Aug 4, 2014 at 13:47
  • 1
    -1, Portable Appliance Testing (PAT) is not an annual requirement in UK law. According to the UK HSE, equipment must be maintained. In low-risk environments (homes, offices) you don't need an electrician to test equipment, a visual inspection is enough. For computers, HSE suggest a visual inspection every 2-4 years. If not double insulated, HSE suggest combined inspection and testing every five years. Note these are suggestions, not legal requirements. Aug 4, 2014 at 14:24
  • THX. Changed "requirement" to "recommendation".
    – JezC
    Aug 4, 2014 at 14:40

There are two ways to let your fuses blow (I presume you use fuses and not the circuit breaker):

  1. Overloading in this case your computer was consuming more than lets say 15A x 200V = 3kW. This unlikely a computer will consume a 100W or something like that.
  2. Shortcut will also blow the fuses by a very high current caused by a isolator failure.

In case of a circuit breaker, this thing can also be activated by earth leakage.

A voltage stabilizer makes things worse due bad energy efficiency. And the electronic power supply can energize your computer in a width range of voltage fluctuations. (Sometimes is a 110/220V switch not necessary because the PS works on all voltage levels.)

Keep it save !


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