CAT II vs. CAT III??? - Page 1
Forum section: electronics / testgear

author: gooseEL34
author_rank: Regular Contributor
timestamp: September 24, 2014, 12:56:51 pm
content: Ok. So I bought a set of $7 ebay test leads. I know on the front end, that I am probably not getting legit CAT III items as advertised. When they arrive, I look at them and the barrel of the leads clearly is embossed with CAT II and it has 1000v MAX and 10A also embossed on the barrel.So my question is this:What markings should be on a CAT II lead?ThanksTim

author: Fungus
author_rank: Super Contributor
timestamp: September 24, 2014, 02:17:00 pm
content: "Cat III" isn't just about volts/amps, it's also about the shape of the probes (how far away are your fingers from metal when you hold them?), materials used, etc.ie. They can be rated for 1000V/10A but still not meet CAT III requirements.OTOH if it says "CAT II" right there on the leads then you can safely assume theyaren'tCAT III.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 24, 2014, 04:57:58 pm
content: The leads that came with the CAT II 600V Gossen 30M are marked as CAT II 1000V 16A on the barrel, with the double square isolation symbol.The yellow removable tip cover is marked CAT III 1000V 1A and CAT IV 600V 1A.So, it looks like your leads are marked correctly for a CAT II set of test leads.

author: Neilm
author_rank: Super Contributor
timestamp: September 24, 2014, 06:40:10 pm
content: When using test leads and CAT rated equipment, the rating of the assembly is the lowest one you can see.So, if your leads come with small covers that then mean they are CAT III, the cover should obscure the lower rating. However, it is not quite as simple as that sounds as some of the CAT ratings have the same clearance requirements for instance 1kV CAT II might be the same as 600V CATIII. ( I don't know if they are or not). Where this happens, either rating can be displayed as long as it is clear that (in the above example) the lead is good for 600V CATIII installations OR 1kV CAT II installations.

author: gooseEL34
author_rank: Regular Contributor
timestamp: September 24, 2014, 11:00:54 pm
content: Ok... So CAT rating has to do with how close the lead lets you get to voltages when being held AND ALSO how much current they can safely pass AND the maximum safe voltages they can test??Ok...I use a few meters. I have a FLUKE 29 series II, a 189 and a 89 (all pawn shop finds).I mainly use a meter for troubleshooting guitar amps. Sometimes my voltages exceed 475 v DC but rarely. Rarely do I measure more than 350v AC (only after the AC transformer, but before diode rectification).Most of the time, the current I am measuring is in the mA range (current draw of a power tube at idle, etc.).I am assuming that a lead marked CAT II should be sufficient for this application, yes?

author: HKJ
author_rank: Super Contributor
timestamp: September 25, 2014, 06:25:37 am
content: Quote from: gooseEL34 on September 24, 2014, 11:00:54 pmCAT rating is based on what type of transients that can occur.The short and simplified explanation is:CAT2: Is for use in you living room, i.e. after normal mains outlets.CAT3: Is for industrial and local power distributionCAT4: Is for outdoor