Useing a higher rated fuse?

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Lonecat

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My fuse broke and I'm looking for a knew one the old one was rated at 20 amps 32v but I'm having troubles finding that rating in the size I need. So I go to the store and find 20amp 125v fuses. The guy I get to talking with said to just go for it and use the 125v and that it wont matter. That seemed very odd to me?
 
dingbat

dingbat

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He is correct.

You can use a fuse rated for a higher voltage, but not vice versa

Curious, what is using 32 V power
 
MTboatguy

MTboatguy

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Often times you will see 32 volt fuses in auto applications, which really don't mean much, you need to be concerned with amp rating and the clerk was correct. Back in the old days of the 60's and 70's that was the normal volt rating you saw on automotive fuses.

Nothing used 32 volts, that was just the high limit of the fuse.
 
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Lonecat

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Well got out to the water and took a look at the fuses and it says AC on it........... Does it matter?
 
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mike_i

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it's been too many years since my basic electronics class but If I remember correctly there is a difference between an AC and DC rated fuse. It has something to do with the fuse element burning open and the arc it causes. I'd read about it and confirm before using an ac rated fuse on a DC circuit. The higher voltage rating is ok as long as you use the same current rating.
 
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mike_i

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how did you determine that from the link? I just did a quick search and found conflicting opinions. This link mentions what I remember from my past electronics classes as I mentioned above. http://solarhomestead.com/difference...-and-dc-fuses/



When an AC fuse blows, it will only open the circuit a few millimeters as that is all that is necessary. If you use an AC fuse with DC current and the circuit is opened (fuse blows), one of three things will happen:
  1. The gap made by the open fuse will be too small and the DC current will jump across, get hot and melt (fuse) the metals back together. This is very dangerous as the condition that caused the fuse to blow or breaker to trip is still there. Now the wiring will heat up and eventually catch fire.
  2. The gap made by the open fuse will be too small and the DC current will arc continuously until it has melted everything around it and/or caught your home on fire.
  3. The gap will arc and melt until the gap opens far enough to extinguish the arc (spark). Although this is physically possible, I have never seen it."
DC CIRCUITS MUST BE OPENED FAST AND FAR ENOUGH TO EXTINGUISH (GET RID OF) THE ARC!

THIS IS EXACTLY WHAT A DC FUSE DOES! IT OPENS THE CIRCUIT FAST AND FURIOUS TO PROTECT YOUR VALUABLES!



Lonecat said:
Well looks like this data sheet says I can use it for DC? https://www.ficcorp.com/content/AGA-Datasheet.pdf
Click to expand...
 
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M

mike_i

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That's a lot better, that fuse will work. you should be able to by them at any auto parts store, walmart or home depot. should be easier and cheaper to get than going thru amazon. Also, remember if a fuse blows it blows due to an over current situation and the problem is still there unless you found the issue and fixed it. Depending on your situation you may want to upgrade the fuse and holder to the newer blade type. I have had those glass fuses go bad, the end caps come loose from the glass tube. Good luck whatever you do.

Lonecat said:
That's the wrong link I tried uploading, and now I cant find the right one :facepalm:


But from what I gather is this type of fuse https://www.amazon.com/Bussmann-AGA-...RM1T91NXZT7SP5 will work for DC just at a slightly lower voltage
Click to expand...
 
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