Products > Test Equipment

Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter )

<< < (8/43) > >>

Fungus:

--- Quote from: robert.rozee on April 15, 2023, 09:50:52 am ---my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.

--- End quote ---

With the dial and leads in the correct position? I'd put my money on "not much apart from displaying the voltage on screen".

Even with the meter in this thread I'd go with "not much".

I haven't traced the circuit out but it appears to be made by a company that takes things seriously. I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it.

Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!

Not everybody goes near mains electricity though and it's perfectly OK to buy one of those meters if you don't.

If you work on mains AC all day long? Get a suitable meter.

PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?

robert.rozee:

--- Quote from: Fungus on April 15, 2023, 11:14:31 am ---
--- Quote from: robert.rozee on April 15, 2023, 09:50:52 am ---my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.

--- End quote ---
I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it. Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!
--- End quote ---

not quite sure what you've written is entirely clear, but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating. with this, i would broadly agree. there are many standards from around the world, but i would agree that being able to withstand a 2.5kv surge is a reasonable compromise for measuring domestic AC.

but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then, well, why do we even bother having these safety standards?!

i think we all agree that DT-830 style multimeters are not suitable for measuring domestic AC mains voltages. i am just going one step further to suggest that manufacturers and retailers of such multimeters should be held accountable for selling a product that does not comply with the relevant safety standards. ie, farnell should not sell such products, repco and bunnings (or walmart or ASDA) should not sell such products, ebay should not allow such products to be listed on their site.

as an alternative, it should be fine for anyone to sell products that either comply with the relevant safety standards (the Fluke 101 provides a good example), or that are constrained to be usable only within safe limits - that is <50v RMS or thereabouts. either step would not seriously impact the manufacturing cost: remove the 500/1000/2kv ranges, limit the display of 200v ranges so that the multimeter displays an 'over-range' for anything over 72v AC/DC, move current ranges to a separate uA/mA input socket, redesign PCB layout and component choices to meet minimum creepage and clearance distances.

after all, if i were to set up shop selling pairs of rubber kitchen gloves marked in big letters across each glove as "250v safe", how long would i be allowed to stay in business?



--- Quote from: Fungus on April 15, 2023, 11:14:31 am ---PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?
--- End quote ---

i take reasonable precautions around mains AC voltages. if i have any doubts about what i am doing, i STOP. that is simple common sense, coincidentally one of the least common commodities in this universe.


cheers,
rob   :-)

Fungus:

--- Quote from: robert.rozee on April 15, 2023, 01:17:40 pm ---but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating.

--- End quote ---

It's not an "assertion".

It's the requirement for a meter to be labelled "CAT II 300V", as defined by industry experts.


--- Quote from: robert.rozee on April 15, 2023, 01:17:40 pm ---but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then...

--- End quote ---

I'm not saying that at all.

What I'm saying is that I would carefully use this meter to measure 230V mains in a pinch, if there was nothing better around.

Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it. I don't recommend it though and I always wear mine.

Careful driving isn't a substitute so that's why I added "If you work on mains AC all day long? Get a suitable meter.".


PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains".

robert.rozee:

--- Quote from: Fungus on April 15, 2023, 06:55:35 pm ---PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains"
--- End quote ---

the DO3047 has 500v written SIX times on the front of it, including the two ranges (AC and DC) labelled 500. an average reasonable person (as defined in law) would be hard pushed to not assume it was safe for making measurements up to 500 volts. the "cat I" text occurs just once. i see that "CAT I describes secondary circuits not intended to be connected to the mains electricity supply" (https://www.flir.com/discover/professional-tools/what-do-cat-ratings-mean/). off the top of my head, i can not think where the average person might today encounter such a defined source. in times gone by, perhaps a battery-powered fluorescent lamp? but today, no.



--- Quote from: Fungus on April 15, 2023, 06:55:35 pm ---Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it
--- End quote ---

it is a poor analogy, "About 90 people are killed every year on New Zealand roads because they weren't wearing a seatbelt" (https://www.nzta.govt.nz/about-us/about-waka-kotahi-nz-transport-agency/annual-report-2018-19/safety/). our front-line police officers have the unpleasant task of attending to those 90 dead, mangled bodies. extrapolating worldwide, that is around 144,000 dead, mangled bodies.

Bud:

--- Quote from: EEVblog on April 14, 2023, 10:40:42 am ---
--- Quote from: David Aurora on April 13, 2023, 12:01:17 pm ---Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.

--- End quote ---

Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.

--- End quote ---
Yeah, I am not sure if the guy has ever used an oscilloscope. Or even knows what it is.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod