Amprobe caught using fake HRC fuses. - Page 1
Forum section: electronics / testgear

author: ivan747
author_rank: Super Contributor
timestamp: April 01, 2013, 09:12:53 pm
content: This fuse used to be in my AM-220. I blew this 440mA fuse a while ago so I kept it in my parts bin as reference. I broke it in half yesterday for a tutorial. Guess what I found? It's fake!It's supposed to be filled with sand or other insulating material.

author: ve7xen
author_rank: Super Contributor
timestamp: April 01, 2013, 09:34:49 pm
content: I don't think Amprobe has specified HRC fuses for this meter. The specsheet lists '250V 0.5A' and '250V 10A' fuses; HRC devices would be rated for kV (and kA rupture capacity). This appears to be a standard ceramic body fuse.

author: Unknown
author_rank: Unknown
timestamp: April 01, 2013, 10:10:08 pm
content: I'm pretty sure this does not conform to IEC 61010. The 500 mA input is shared with the volt/Ohm jack, and is labeled CAT III 600 V. I doubt that this fuse is going to survive the transient dictated by IEC 61010 for a CAT III 600 V input. I believe IEC 61010 also states that the equipment should be safe, regardless of switch settings. So 600 V with a 4 kV (?) transient should be perfectly safe with the switch set to mA, but I wouldn't trust this fuse to interrupt 600 V, let alone 4 kV.Of course the input is also labeled CAT I 250 V / 600 V, so you get free choice of which of the three standards you want to apply. Treating it as CAT I 250 V would probably be the only safe solution, although they somehow want you to believe that it can measure CAT III 600 V circuits.So you can measure CAT III 600 V circuits, as long as it's not set to measure current. What's the most common reason of blown fuses again? Something about people accidentally measuring voltage while the meter is set to measure current?Edit: never mind. According the data sheet, protection on resistance, diode/continuity, capacitance and frequency mode is also limited to 250 V. Treat this just like a CAT I 250 V meter, and ignore any other markings (I would take a sharpie and cross them out). It's just another meter with false safety claims. As if the Chinese brands like Uni-T weren't putting out enough of these already.

author: ivan747
author_rank: Super Contributor
timestamp: April 02, 2013, 03:07:30 am
content: To the unsafe list of multimeters it goes!

author: nanofrog
author_rank: Super Contributor
timestamp: April 02, 2013, 04:59:14 am
content: Meters claiming CAT ratings they can't fully pass is just insane IMHO.Unfortunately, so long as there's nothing to even make them think twice about such an act (financial penalties, time in prison if someone dies, ...), I don't see an end to this from unscrupulous manufacturers.

author: em132
author_rank: Contributor
timestamp: April 03, 2013, 10:32:53 am
content: Quote from: alm on April 01, 2013, 10:10:08 pmFWIW, the Bussmann fuses used in UNI-T's 61 series DO have sand in them.

author: Monkeh
author_rank: Super Contributor
timestamp: April 03, 2013, 11:17:12 am
content: Quote from: em132 on April 03, 2013, 10:32:53 amAnd are rated at minimum 6kA breaking capacity.

author: ivan747
author_rank: Super Contributor
timestamp: April 03, 2013, 01:30:09 pm
content: The Amprobe AM-530/520 seem to be manufactured or at least designed by UNI-T.They use Bussman fuses too and the 10A is supposedly rated for 20kA breaking capacity. For $10-$20 more they seem a much better deal. The 530 is TRMS.