Operating Fuses using AC or DC Voltages

I was reading one of the usenet groups the other day, and came across a posting I replied to. The poster was asking about available voltage ranges for fuses {AC voltages}, as he could not find the [absolute] correct voltage rating for a fuse. My reply was basically a quote right off the page for Manufacturers of Fuses.

"The voltage rating of the fuse does not indicate the operational voltage of the fuse. The voltage rating determines the maximum voltage that will not jump the gap between the elements after the fuse has already blown. So the fuse will operate at the rated voltage and any voltage below the rating. "

Someone replied back indicating that in fact I was not correct and that;

".. DC is a more severe condition. ... You should not use an AC rated fuse in a DC circuit. ..."

Followed by another poster who had this to say;

"The AC/DC differential tends to be glossed over a lot .... . One way this shows up as physical difference in AGC style fuses is that DC rated fuses are often ceramic rather than glass, presumably to contain the arc."

I took note of that reply and turned to the internet to research the issue. I came across a site that seem to indicate the same thing I was saying. In the mean time others replied as well. I posted the quote I found on the internet and also a quote from a US Military Standard.

"... once the fuse has opened, any voltage less than the voltage rating of the fuse will not be able to "jump" the gap of the fuse. Because of the way the voltage rating is used, it is a maximum rms voltage value. ..."

MIL-PRF-23419: Fuse selection: The following steps should apply in the selection of a fuse for any application: Step 1: Select a fuse with a voltage rating equal to or in excess of the circuit voltage.

Ya know, if it's good for the government. In fact the third section of MIL-PRF-23419 indicates this:

1.2.1.3 Voltage rating. The voltage rating is the maximum dc or ac root mean square (rms) voltage for which a fuse is designed (see 3.1). The voltage rating is identified by a numerical value followed by the letter "V".

In fact if one of the "/" documents are referenced you'll find that the maximum voltage rating provided does not indicate AC or DC values, just 125 V [MIL-PRF-23419/H].

It appears that the newsgroup thread has ended [at least until the week end], but I kept looking into the voltage issue. I came across data that I intend to add to a new page covering the Difference between AC & DC Fuses. Because of this blog entry, generating that new page, up-dating the sitemap, and adding a new page to the What's new Blog; the new page is just a copy of a per existing page with a new page address. I should get some data out there within 12 to 24 hours.

Caution; always check the IEC, NEC or any other standards body that regulates Fuses. Never rely on the web for information when it comes to personal safety.