Are all fuses created equal?

If they're correct rating and UL listed, they should be.

Hi Nick,

I suspect that the original fuse was a Cooper Bussmann MDL-2-R, for which the manufacturer's datasheet is shown here. Does that appear to be correct?

And what is the manufacturer's part number of the replacement you ordered? That number should be indicated on the catalog page of the distributor you ordered it from. It should then be possible to find the manufacturer's datasheet for that part number, and compare the technical specifications of the two fuses.

Without comparing the specific technical data, I don't know what the differences are between the MDL and ADL series. Based on a quick search, I couldn't find any relevant information about ADL types.

To address the more general questions, the major manufacturers of standard fuses, such as Cooper Bussmann and Littlefuse, provide detailed technical info in the datasheets that are available at their websites. I haven't had occasion to make any comparisons between their specs for similar fuse types, but I would expect that for similar fuse types made by the major manufacturers some spec differences would exist, but they would be minor.

I would not expect the same to necessarily be true in other cases. I have seen a number of posts here in the past indicating that users have found some Radio Shack slow blows to act more like fast blows. And concerning audiophile-oriented fuses, I second Elizabeth's earlier comments.

Concerning substituting slow blows for fast blows and vice versa, obviously substitution of a slow blow for a fast blow will compromise protection to some degree, while substitution of a fast blow for a slow blow may result in frequent blows that are unnecessary.

Best regards,
-- Al

Al thanks for the input. After some quick research I found the data sheet for the ADL fuse, it is from Conquer here is the data sheet.

So the question now is, what aspect of the data must be compared?

Thanks again

Hi Nick,

While there are a number of differences between the specs for the two fuses, I don't see anything all that dramatic. Although the Conquer ADL datasheet is not nearly as comprehensive as the Buss MDL datasheet.

The Conquer ADL has a nominal melting spec of 48 amps squared-seconds. The corresponding figure for the Buss MDL fuse is 62.3, which would suggest that the ADL will blow a little bit more readily. However, those are nominal (typical) figures, and each fuse can be expected to have a fairly wide tolerance (range of variation) about those numbers. Also, the specific test conditions are not indicated in the case of the Conquer fuse.

Both datasheets provide figures for min and max blow times at 200% of rated current (which would be 4 amps in this case). Those numbers are 5 seconds min and 120 seconds max, for both fuses.

"Interrupting ratings" are 100 amps at 250 VAC in both cases. Cold state resistance is spec'd a little higher in the case of the Conquer ADL fuse, but the ADL datasheet doesn't indicate what current level that is measured at, so direct comparison is iffy. And that number doesn't have much if any relevance to protection anyway.

That covers essentially all of the relevant specs that are provided in the ADL datasheet. The Buss MDL datasheet is more comprehensive, as I said, so a fully conclusive comparison can't be drawn. And who knows how accurate the specs are? But based on the info that IS provided on the ADL fuse I don't see any worrisome differences.

Best regards,
-- Al