Hoping to get some help understanding fuse naming codes for the small cylinder glass and ceramic type fuses seen in appliances, etc. I would think that this information would be fairly easy to come by but I've been having trouble finding anything that is clear and thorough.

For example, I have a fuse stamped F15AH250V. I would assume 15A 250V but what do the F and H refer to? Is this the overall format: _ # Amp _ # V. If so, what are all the possible codes for the letter designations and what do they mean? Are the codes different between fuse manufacturer or is it standard? If all specifications match but one fuse is glass and one is ceramic are they still a match? Just trying to get a better understanding of this since it's come up a few times for me. Looking for as complete a source as possible. Thanks

Start here, then on to your type of fuse:
1/4" x 1-1/4" Ferrule

Thanks, the data sheets for each fuse are very informative, but none of the numbers match my fuse. These fuses look they all start with a 3-letter code (ABC, AGC, GBB, etc.) Mine simply says F15AH250V. I'm sure there is a suitable match in the website you posted, but not knowing how to decipher my code I'm at a loss. I was hoping that all of this naming was a bit more standardized. I see that these are called Ferrule fuses so I at least know how to properly refer to them (if that is a universal name for the type of fuse and not just specific to Cooper-Bussman).

Fuses use manufacturer numbers, the only standard is the Class #.

The number you have is a generic catalog number, probably OEM for appliances.

Best you can do is to match the fuse to something similar.

Need to stay with the ceramic 15 amp 250 volt rating of the same physical size.

Need to check with the manufacturer of the applaince to determine if the fuse needs to be fast acting or time delay (Slow Blow).

Thanks. Which one is the 'Class #' you mention?

What I'm gathering is that if the old one is ceramic, the new one needs to be ceramic and if the old one is glass the new one should be glass? Am I correct to assume that the only criteria are:

1) voltage rating
2) current rating
3) housing material (ceramic or glass)
4) physical size
5) action time (fast-acting or slow-blow)

If I assume that this covers all bases will I be okay? Or are there other properties I should know? I've certainly used this general criteria in the past to replace fuses without problems, but I figured I might as well try to get a better understanding if I could.

If I need to guess at a replacement, I assume it's better to start with a fast acting type rather than the slow blow? I also see there are 'very-slow acting' etc. varieties. It's a shame this is not more standardized.

This site is saying that the 'H' means 'high breaking capacity' but not sure if that refers to the fuse element or the ceramic casing.

http://www.screwfix.com/community/message/1178340

Quote:

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Originally Posted by lee12

Thanks. Which one is the 'Class #' you mention?

What I'm gathering is that if the old one is ceramic, the new one needs to be ceramic and if the old one is glass the new one should be glass? Am I correct to assume that the only criteria are:

1) voltage rating
2) current rating
3) housing material (ceramic or glass)
4) physical size
5) action time (fast-acting or slow-blow)

If I assume that this covers all bases will I be okay? Or are there other properties I should know? I've certainly used this general criteria in the past to replace fuses without problems, but I figured I might as well try to get a better understanding if I could.

If I need to guess at a replacement, I assume it's better to start with a fast acting type rather than the slow blow? I also see there are 'very-slow acting' etc. varieties. It's a shame this is not more standardized.

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Your list is exactly what I outlined:

Need to stay with the ceramic 15 amp 250 volt rating of the same physical size.

Need to check with the manufacturer of the applaince to determine if the fuse needs to be fast acting or time delay (Slow Blow).

To be safe, sure using a fast acting is suggested, however, if the load needs a slow blow, fasting acting may result in nusiance failures.

That is why I made the statement:

Need to check with the manufacturer of the applaince to determine if the fuse needs to be fast acting or time delay (Slow Blow).

What exactly are you trying to accomplish?

Trying to accomplish finding an answer to the question - 'Is there a standard system for naming fuses?' Looks like the answer is 'no'.

Really was just wondering for my own curiosity. Not really concerned about the fuse I gave as an example, I just picked that one because it was one that I was not able to find anywhere on the internet. That's when I started looking for an explanation for fuse codes and could not find anything. That's when I thought to post it here.

To learn all about fuses, you can get this free handbook by a simple registration:

Selecting Protective Devices Handbook

You will see that there is no simple answer for your question.

Thanks - looks like quite a good resource, nice of them to offer it free. Thanks again for the help.

I need a data sheet explaining the 3 and 4 letters in the fuse code.

I assume you mean the UL Class code letters:

UL Fuse Classification Chart - Electrical References - Elliott Electric Supply

Each manufacturer will have a chart in their catalog listing these Class codes.