What amp fuse to i need for my PC?

Associate
Joined
7 Sep 2005
Posts
37
Location
London
Hey all,

Up til now, i've been using a 5amp fuse in my power cable, but some are now telling me that i should not be using more than a 3amp fuse for a PC. Then there is a professional electrical company who came into my place of work the other day to test a whole load of power cables, and said that a 5amp fuse would be the best versetile choice to fit into a power cable to use on both screens and PCs. So im getting mixed messages and just wanted some confirmation. :confused:

I personally have a good PSU, and i would like to think that if 5amps where a little too much, that my PSU would regulate it. In any case, this was more a general question that i was curious about.

Please help. :)
 
Associate
Joined
15 Jan 2003
Posts
662
Id stick with a 3 Amp, simple reason being its a lot easier and cheaper to replace a fuse than pc parts, if its constantly blowing then and only then consider 5Amp, although im actually using a 13Amp fuse in One of my monitor cables :/
Gonna go change that tonight
 
Soldato
Joined
3 Nov 2004
Posts
9,857
Location
UK
What's the power supplies peak wattage rating and efficiency?

Ignoring PFC. Say its 70% efficient and rated to 480w. So if it needs 480w it will consume 480/0.7= 685w at 230vac. Or 2.98A. I'd think most PC's would need a 3A, an overclocked a 5A.
 
Permabanned
Joined
10 Apr 2004
Posts
13,122
Location
Darlington, County Durham
I think a 3 amp fuse will suffice.

Don't forget, if you have a 13 amp fuse in a device which only needs 3a, then if anything shorts out it'll take longer for the 13a fuse to burnout. Meaning more time for the shorts to do their damage.
 
Associate
OP
Joined
7 Sep 2005
Posts
37
Location
London
fornowagain said:
What's the power supplies peak wattage rating and efficiency?

Ignoring PFC. Say its 70% efficient and rated to 480w. So if it needs 480w it will consume 480/0.7= 685w at 230vac. Or 2.98A. I'd think most PC's would need a 3A, an overclocked a 5A.

Whats that got to do with a 'general' question. My PSU shouldnt come into it, as everyone else in the world would have a variety.

My own PSU is a Seasonic S12 430W BTW.
 
Soldato
Joined
3 Nov 2004
Posts
9,857
Location
UK
Fuzzi Bear said:
Whats that got to do with a 'general' question. My PSU shouldnt come into it, as everyone else in the world would have a variety.

My own PSU is a Seasonic S12 430W BTW.
Of course it does, what do you think is drawing power from the mains? All the mains fuse does is isolate the PSU. As far as the mains is concerned the PSU is your PC. The fuse of any equipment is rated to its peak power consumption and that includes start up surge current and operating efficiency. It should also account for reactive power. Of course there's a variety, you think every PC should have the same size fuse just because its called a PC.
 
Last edited:
Soldato
Joined
3 Nov 2004
Posts
9,857
Location
UK
Fuzzi Bear said:
I personally have a good PSU, and i would like to think that if 5amps where a little too much, that my PSU would regulate it.

Just to clarify in case your confused. All a fuse does is stop a device pulling to much peak current. Some fuses blow fast if they see to much current, some blow slowly and allow over-current surges for a small time they're called thermals. The fuse can't regulate anything, they isolate circuits that pull to much current, maybe a dead short or failing insulation. leakage.

Single phase domestic mains outlet fuses only come in the three sizes, 3, 5 & 13. The electrical (like the one's inside your PSU) Cartridge or pigtail fuses come in all kinds of sizes and rates. The lack of domestic mains fuse sizes has always annoyed me tbh. The best way to stop electrical fires is to rate the fuse correctly. What uses 13A/3kW anyway? 5A should be the standard, but they always put in 13A.
 
Last edited:
Associate
Joined
30 Nov 2002
Posts
1,851
Location
Birmingham
fornowagain said:
What uses 13A/3kW anyway? 5A should be the standard, but they always put in 13A.
Sadly true.. goodness knows what I'm using but I'd bet nearly every one is a 13A and the only ones needing more than 5 would I'd summise be the Kettle and Iron.
 
Associate
OP
Joined
7 Sep 2005
Posts
37
Location
London
fornowagain said:
Of course it does, what do you think is drawing power from the mains? All the mains fuse does is isolate the PSU. As far as the mains is concerned the PSU is your PC. The fuse of any equipment is rated to its peak power consumption and that includes start up surge current and operating efficiency. It should also account for reactive power. Of course there's a variety, you think every PC should have the same size fuse just because its called a PC.

My point was what does 'MY' particular power supply got to do with the general question i asked? - i am asking a general question which applies to everyone. So asking what my own personal PSU is, is no help.

I've been told that printers, PCs, and monitors are all best on a 5A fuse. This was a cable testing company that told me this, and they specialise in PCs etc. so i was just wondering if others agreed with that?

:)
 
Soldato
Joined
3 Nov 2004
Posts
9,857
Location
UK
Fuzzi Bear said:
My point was what does 'MY' particular power supply got to do with the general question i asked? - i am asking a general question which applies to everyone. So asking what my own personal PSU is, is no help.

I've been told that printers, PCs, and monitors are all best on a 5A fuse. This was a cable testing company that told me this, and they specialise in PCs etc. so i was just wondering if others agreed with that?

:)
I said "What's the power supplies peak wattage rating and efficiency?" I didn't say "what's yours". And that is the only correct answer you will receive from an electrician. Answer that and you can then ask for the fuse rating.

If you wish to be pedantic, there can be no general answer. However as I said there are only three choices. In practicality, consider the average maximum draw of any particular generic groups PSU's and match it to nearest fuse above rated just above said average. And remaining pedantic, it's the PSU the fuse protects not the PC. The PSU has it's own fuses for the PC.

Or normal PC's 3A and power hungry PC's 5A.
 
Last edited:
Associate
OP
Joined
7 Sep 2005
Posts
37
Location
London
fornowagain said:
If you wish to be pedantic, there can be no general answer. However as I said there are only three choices. In practicality, consider the average maximum draw of any particular generic groups PSU's and match it to nearest fuse above rated just above said average. And remaining pedantic, it's the PSU the fuse protects not the PC. The PSU has it's own fuses for the PC.

Or normal PC's 3A and power hungry PC's 5A.

Finally a semi-sensible anwer. thank you for that.

Pedantic or not, the answer you gave WAS in reply to the exact question i asked. Its as if i wanted to start selling fuses on the open market... which would i need to stock up on for the majority of people's needs? - it was that type of question. Which, you've answered well for me. thanks again.
 
Associate
Joined
17 Feb 2006
Posts
898
Location
Fleet
why not work out the current draw on everything on your pc/printer etc and choose the fuse accordingly. there is no right answer on what fuse everyone should use. just use the equation P=VI and use the next fuse up from the answer you get for the current.
 
Soldato
Joined
3 Nov 2004
Posts
9,857
Location
UK
Ladforce said:
why not work out the current draw on everything on your pc/printer etc and choose the fuse accordingly. there is no right answer on what fuse everyone should use. just use the equation P=VI and use the next fuse up from the answer you get for the current.
That's what it says two posts up.
 
Associate
OP
Joined
7 Sep 2005
Posts
37
Location
London
Ladforce said:
why not work out the current draw on everything on your pc/printer etc and choose the fuse accordingly. there is no right answer on what fuse everyone should use. just use the equation P=VI and use the next fuse up from the answer you get for the current.

I dont want to know what fuse to use FOR MY PC!...

Stop it now please. :mad:

I was asking a general question, which has now been answered as best as it can be.

I bet if i had asked:
"if i tree fell in the woods and there was nobody around to hear it, would it make a sound"...

I'd get some kind of replies such as "what kind of tree"..

Jes....

Oh well. im done banging my head on the wall now. :p
 
Associate
Joined
3 Dec 2015
Posts
3
Hello guys
Any idea why computer power cord lead plug could melted in smoke ???
I add it never happened before - once when comp was taking too much power for this what power supply could do, power supply just burnt out, But now just plug melted.
That was during extensive use I mean playing game.
I recently changed GPU to Gigabyte GTX 980 Ti G1 and I got AMD FX 8350
Here http://www.bit-tech.net/…/gigabyte-geforce-gtx-980-ti-g1…/10
they say loaded using about 451 (not OC)
and here http://www.bit-tech.net/hardwa…/…/11/06/amd-fx-8350-review/7
my processor using around 213 when on load
together is 664W
My Power supply is 750 Corsair, and Gigabyte recommendations is 600W up
but any way - even if comp taking to much power then power supply should go first not a cable
I add we got fuse in plugs in each cable and it melted exactly there

11255402_10206615003208208_2312958523365437599_n.jpg


12347938_10206615003768222_5142481874833312906_n.jpg
 
Associate
Joined
30 Dec 2012
Posts
83
What uses 13A/3kW anyway? 5A should be the standard, but they always put in 13A.

Heaters, kettles, large toasters, hot plates, griddles, a lot actually, the question is, why do manufacturers use 13A as standard (for the most part).

You do realise though, the fuse is meant to protect the cable only. The items short and fault protection comes from your rcd/mcb/rccb/rcbo. The fuse in the plug should be sufficient to protect the cable in the event of overload, so the cable doesn't melt or worst case, cause a fire before the fuse blows. In the event of a fault, the circuit protection should jump in and save the day, think of all the times you've plugged in something faulty, your breaker tripped but the fuse in the plug didn't blow... there's why.
 
Back
Top Bottom