32v. vs 250v.

[BoatBuoy]

Due to deteriorating insulation, I spent the afternoon replacing a good portion of the wiring on my motor. In the process, I had to replace the in-line fuse holder. Since I already had one, I used it. The original used a short glass fuse which was 20amp, 32 volt. The one I used takes the 1.25" glass fuses. Since I have a bunch of 20 amp, 250 volt fuses which fit, does the voltage matter or should I seek a 32 volt fuse?

 

[18rabbit]

Re: 32v. vs 250v.

The 250volts doesn’t matter. The 20amps does…that’s the weak link in a fuse and the reason why it fries. Also be aware that using an AC-only rated fuse in an DC circuit could result in the fuse exploding. That would be a no-can-do that also matters. Many of the little glass fuses are rated for AC/DC, so not a problem. If the fuses you have are labled for DC or AC/DC you are good to go.<br /> <br /><br />Edit: something else came to mind… You may also want to match the speed of the old fuse, i.e. if the old fuse was a fast-blow, replace it with a fast-blow, and of course replace a slo-blow fuse with another slo-blow.

 

[BoatBuoy]

Re: 32v. vs 250v.

Thanks, rabbit.

 

[TwoBallScrewBall]

Re: 32v. vs 250v.

Rabbit, I'm not sure you're right. <br /><br />250 Volts at 20 Amps makes 5000 watts.<br /><br />32 Volts at 20 Amps makes 640 watts. <br /><br />That's a big difference in power, the 250 volt fuse will need to see over a 5000 watt drain to blow where the 32 volt fuse needs only 640. Say you had a short that created a 2000 watt draw on your wiring. The 32 volt fuse will pop, but the 250 volt fuse will be perfectly happy letting your wiring melt down. <br /><br />I think...

 

[Ralph 123]

Re: 32v. vs 250v.

A fuse is designed to blow at a given current not a given power. In theory, a fuse drops 0 volts (it's a short) and therefore consumes no power. In reality that have a resistance associated with them (R) and do consume power as I^2 x R<br /><br />

Fuses may be used in any application where the open circuit voltage does not exceed the fuse voltage rating AND the prospective short circuit current is below the fuse interrupting rating. Fuses can be used at any voltage below the fuse voltage rating: a 250V can be used in 125V circuits

http://www.belfuse.com/Data/DBObject/fuseterm.pdf <br /><br />And just to confirm<br /><br />

What is Voltage Rating?<br /><br />The voltage rating specifies the maximum voltage for the circuit in which the fuse is used.<br />

http://www.bluesea.com/Article_Detail.asp?ID=121&Page=1&section_Id=140

 

[amirm]

Re: 32v. vs 250v.

Ralph is very much correct. The voltage rating just needs to be higher than you need. It has no bearing otherwise. Ralph provides the math but essentially, the fuse does not consume any power. Otherwise, it would be a highly ineffecient device!<br /><br />Also, slo-blo fuses are rather rare these days. You can tell them apart from normal ones since it looks like a spring inside than a straight wire.<br /><br />Amir

 

[Tatorbug]

Re: 32v. vs 250v.

The voltage rating of a fuse is the maximum voltage the element can withstand after the fuse blows without arcing. The higher voltage fuses can always be used in lower voltage circuits. If you use a 32v fuse in a 250v circuit, the fuse could continue to arc inside after it blows.

 

[TwoBallScrewBall]

Re: 32v. vs 250v.

Aah I see,