Clamp meter safety - Page 1
Forum section: electronics / beginners

author: Haggai
author_rank: Contributor
timestamp: March 20, 2011, 11:34:26 am
content: If I use a crap clamp meter only for its clamp (even though it has leads inputs available) - is there any danger if measuring large currents?I have this one:http://cgi.ebay.com/VOLT-METER-MULTIMETER-AMPS-AC-DC-DIGITAL-VOLTMETER-OHM-/190487354836, opened it up today just to reveal it has no fuses whatsoever, and I'm not even sure of any other input protection.I'm not looking for accuracy, 10% error is accurate enough for my needs.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: March 20, 2011, 11:44:55 am
content: Dear friend , this is an 10$ toy.The people who invest money at buying toys , they do not deserve to ask ,an such question, like you did.Read the specs , divide the specs at half, so to get an estimate of what it can do.

author: Zero999
author_rank: Super Contributor
timestamp: March 20, 2011, 11:48:29 am
content: I agree, it's a toy.The clamp function only works for AC but I wouldn't recommend it for measuring current through mains conductors unless they're insulated.

author: Haggai
author_rank: Contributor
timestamp: March 20, 2011, 11:55:05 am
content: As I said, I don't care much for accuracy, only for safety.For measuring currents of up to about 20A, only for insulated wires - is it safe?Can something happen if there's a spike of current to 200A? Does it affect the meter in any way other than displaying OL or just wrong measurement?Oh, and just for fun - this meter is sold locally in stores for the equivalent of 30$-40$.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: March 20, 2011, 12:21:43 pm
content: Quote from: Haggai on March 20, 2011, 11:55:05 amOk I bet my life that the plastic cover of this device , in one environment with lots of humidity, its capable to offer you a nice shock.Plus the plastic cover it can become 100 pieces from an simple crash in to a hard surface , and all the inner parts in it,they can easily become exposed.Every device can offer safety, at the hands of the expert user.And the comparison between local price ,and international , its not an indication of quality.

author: Haggai
author_rank: Contributor
timestamp: March 20, 2011, 12:45:07 pm
content: Quote from: Kiriakos-GROk, thanks.So for regular conditions and safe practice, I guess I can live with that.Quote from: Kiriakos-GRYeah, I know.Did you know they sell the UNI-T UT10A for almost 40 USD here?And the cheapest auto ranging from ebay (XB-866) [10USD delivered] for 45 USD. And that's from "respectable" stores...My 3$ crappy meter (DT830B) is sold in stores for 10$-20$, and I saw its puny leads (1.66$@DX) advertised in more than one store as "quality leads" sold for about 10$.Talk about rip-off.

author: tecman
author_rank: Frequent Contributor
timestamp: March 20, 2011, 12:46:36 pm
content: Other than the mentioned issue of safety and insulation around high voltages, there is no danger in reading high currents.Paul

author: Zero999
author_rank: Super Contributor
timestamp: March 20, 2011, 12:52:31 pm
content: Yes, if the wires are insulated, the meter is isolated from the circuit so there's no shock risk.

author: Unknown
author_rank: Unknown
timestamp: March 20, 2011, 01:31:02 pm
content: Except for induced current, if the current through the inductor is high.

author: Zero999
author_rank: Super Contributor
timestamp: March 20, 2011, 01:36:02 pm
content: Quote from: alm on March 20, 2011, 01:31:02 pmI think the current would have to be very high (thousands of Amps) to induce a dangerous voltage inside the meter.

author: Unknown
author_rank: Unknown
timestamp: March 20, 2011, 02:06:27 pm
content: Quote from: Hero999 on March 20, 2011, 01:36:02 pmThat depends on how well the meter is designed. The inductive kick from opening the jaws while a current is flowing can be quite high, although I'd be more worried about damage to the meter than electrocution of a human. Of course something going bang in a meter can be dangerous. Not saying this is likely at 20A, but the fact that the wire is insulated doesn't make it safe.

author: PetrosA
author_rank: Frequent Contributor
timestamp: March 20, 2011, 03:26:41 pm
content: Yeah, it looks like a shit meter, but if you only use it for current measurements on small insulated wires and use leather gloves for protection you should be fine. I would recommend inspecting the plastic on the jaw on a regular basis since for this price it's probably a very brittle type and could crack, exposing the metal inside which would be a shock hazard. If the wires you're checking are fuse or breaker protected at 50A or less, that will protect you from getting current as high as 200A in the jaw for more than a fraction of a second (magnetic breakers will trip quite fast with an overload lasting more than a second or so).

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: March 20, 2011, 10:05:09 pm
content: Quote from: Haggai on March 20, 2011, 12:45:07 pmI love to ... Talk about rip-offThe 360$ Fluke DMM, in Greece and Europe it cost as 600$ .But again this anomaly its not the rule for all brands.Still, I bet that with the UNI-T product you get an true year of warranty,something that proves that the company does have faith on the product,something that the No-name ones does not offer.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: March 20, 2011, 10:24:28 pm
content: Quote from: PetrosA on March 20, 2011, 03:26:41 pmWell If I had not listen your suggestion about the " chauvin arnoux " clamps ,today I would be unable to know of how an high quality clamp, should look and feel like.Ok the one that I got its the top of the cream, AC/DC Amperes , sensitivity 100mA - 600A .And it does not come for free ( 300$ range) .But even with out looking in the book for specs , your hand and eye feels ,that you are holding an item of true high quality of manufacturing.https://www.eevblog.com/forum/index.php?topic=660.0