modified: Sunday 31 July 2016
Inside HRC fuses: cheap vs brand-name
Fuses we are tearing down today:
- SIBA branded 5×20 0.5A from RS-online
- Unbranded generic "5×20 0.5A ceramic" off eBay
My Extech MN16 multimeter takes a 0.5A 5×20mm fuse. Last time this blew (read: a friend borrowed it) I ordered some cheapies to replace it off eBay. When a fuse in another multimeter died, I decided to order some 'branded' replacements from RS components for the MN16 too.
Sidenote: although this multimeter calls for 660V rated fuses, I have had no luck finding them in the 5×20 form factor. Instead I have been installing ones rated to only ~230V. Not perfect, but the best I can do.
I can't remember which way around they were supposed to be in this diagram. Both have slightly ill-fitting endcaps and come in deluxe white.
When we look at the fuses end-on however things become a bit clearer. On the left is the unbranded, on the right is the German:
Whole fuses? Nothing a pair of sidecutters can't fix.
Notice the sand? You could play with Tonka trucks in the SIBA whilst the unbranded was bare-bones empty. Apart from that they look very similar and have identical-looking fuse wires:
Why is there a beach in my fuse?
It looks like the sand is there to quench arcs better than air does. I have no experience with this or testing it, so I can't back this up.
More fuse porn
The fuses I needed to order in the first place:
Some others I now have lying around:
Shame I can't fit these in my DMM. Perhaps I should make a DMM inside them.