View Full Version : are fuses voltage rated?
Can you use a 13A household 240V fuse on your bike as still 13 A 12V?
Cheers
why would you want to? DD says probably not.
cause the fuse holder I want to use for my heated gloves takes fuses that are bigger like a 5A one I have that would fit in a plug.
Actually the box of fuses I bought for my bike says 250V so I guess it's only rated for Amps 12V & 240V would both work
(wouldn't put 10,000 V through the same ones though I guess)
Fuses are made very carefully so that the fuse element heats up sufficient to melt the element & break the circuit.
I'm pretty sure that's due to the power flowing through the fuse element. Power is a function of both voltage and current.
So I suspect (but I've never had a reason to test it), that a 230V 13A fuse running at 12V would require more than 13A to generate enough heat to melt the element. How much more, I don't know.
EDIT: Thinking about it, it'd be energy dissipation, which is current & resistance.
So, I wouldn't try it, but I can't remember what effect it would have. Surely there's somewhere open near you that sells the right fuses?
are you needing heated gloves tonight? halfords open til 630 but you will get cold hands getting there.
I reckon it will be fine :D
I reckon it will be fine :D
Your heated grips will keep your hands warm, and if the bike sets alight, at least your bum will be warm too. :D
dirtydog
31-01-09, 07:05 PM
Just go to Halfords and buy the right ones you tight lazy git
tigersaw
31-01-09, 07:23 PM
No. Fuses are pretty precision items, designed for different applications, some allow a certain inrush current, some will not, some will reset. All will be designed for the safe protection of the application in mind without causing risk of fire.
That aside, any fuse is better than none, and so long as it still remains the weakest link in the wiring will offer some protection.
Just go to Halfords and buy the right ones you tight lazy git
So when I went to Maplins and bought fuses specifically for the bike did they come in a box saying 250V? :smt019
:lol:
dirtydog
31-01-09, 08:08 PM
So when I went to Maplins and bought fuses specifically for the bike did they come in a box saying 250V? :smt019
:lol:
I don't know, I wasn't there was I ya div!
;););)
21QUEST
31-01-09, 08:18 PM
Stu, It'd be okay.
Ben
punyXpress
01-02-09, 09:59 PM
At least 2 generations of bikers used silver foil from fag packets, or milk bottle tops with no worse result than the tits getting at the cream!
northwind
01-02-09, 10:32 PM
I never had a fuse in those wires when I was using em, and I am not yet dead.
Can you use a 13A household 240V fuse on your bike as still 13 A 12V?
Cheers
These calulations are prolly way off, but...
13A x 240V = 3120W
13A x 12V = 156W
So if the first fuse can take 3120W at 240V, lets see what it takes at 12V.
3120W / 12V = 260A
The last sum im deffo not sure about but whichever way i would not think a 13A/240V would pop on a bike any time soon.
These calulations are prolly way off, but...
13A x 240V = 3120W
13A x 12V = 156W
So if the first fuse can take 3120W at 240V, lets see what it takes at 12V.
3120W / 12V = 260A
The last sum im deffo not sure about but whichever way i would not think a 13A/240V would pop on a bike any time soon.
I was thinking this too, however wasn't sure so I didnt comment.
Your calculations are correct for Amps into Watts and Watts into Amps. :)
Dan
These calulations are prolly way off, but...
13A x 240V = 3120W
13A x 12V = 156W
So if the first fuse can take 3120W at 240V, lets see what it takes at 12V.
3120W / 12V = 260A
The last sum im deffo not sure about but whichever way i would not think a 13A/240V would pop on a bike any time soon.
Yes, but is it not the Amps that blow a fuse?, not the Watts?
I've blown a 3A 250V fuse with the bike quite easily without damaging any wires. You're calculations suggest it would have taken over 60 amp to break the fuse
Yes, but is it not the Amps that blow a fuse?, not the Watts?
I've blown a 3A 250V fuse with the bike quite easily without damaging any wires. You're calculations suggest it would have taken over 60 amp to break the fuse
The first two calculations are correct, the last one is in question.
As has been said fuses are carefully calculated for inrush current and constant current. As you have found out clearly a 3A fuse does not work for your application.
yorkie_chris
02-02-09, 02:30 PM
It's the amps that matter, you could put 10kV down a 1A fuse and not pop it if the current was under 1A.
Difference is an AC fuse is rates in amps RMS (average over the AC cycle) AFAIK, whereas DC is a constant rating. Whether this makes any practical difference or not I have no idea. (perhaps some cooling occurs at less than peak voltage?)
Be right. Question is, why did the original fuse pop?
No it did work. I assume there was a short, so it safely protected the circuit.
3*250=750
750/12=60
but i reckon it just depends on the amps (within reason)
so 3A 250V will still work on a bike as a 3A fuse
Heating effect is caused by the current. The power is irrelevant as most of it is dissipated elsewhere.
Eg as the fuse has very low resistance, the voltage dropped across it is probably only 0.1V or less - the rest of the voltage is all dropped across whatever is actually doing the work.
I'd be happy using a household fuse in a bike. They all blow at particular currents, even if some do take slightly longer.
Difference is an AC fuse is rates in amps RMS (average over the AC cycle) AFAIK, whereas DC is a constant rating. Whether this makes any practical difference or not I have no idea. (perhaps some cooling occurs at less than peak voltage?)
Volts AC RMS is the same heating effect as Volts DC. So no difference in most cases.
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