Safe voltages and transformer secondary

[large_ghostman]

well if you watched the video and the bit i put about the title being a little misleading, you would realize it was debunking the myth of its the amps not the volts. personally 30V DC is about my limit before i get careful, i can feel 30V easily but i have YOUNG FRESH skin.

1000V us perfectly safe if you treat it with respect and know what your doing. Look at Derstrom that nutter plays with Tesla coils!

 

[MikeMl]

..."To avoid personal injury, please do not attempt to input voltage higher than 30V rms."...

That is a lawyer talking...

 

[large_ghostman]

That is a lawyer talking...

cant be... i understood every word

 

[Bud_J]

I read many times, form many sources, that 60 VDC or 30 VAC are potentionally dangerous. I know that it is current what matters, but higher voltages lead to greater currents (assuming same resistance, of course).
I also know that primary and secondary windings of a transformer are dangerous.

I do remember this was a study question for the ham radio operator's test way back when. The study text said that as little as 30 volts could kill you, or as little as 1A could kill you.

I'm not saying this is right or wrong, only that I remember it being a study question for the ham radio operator's license test.

I've always kept it in mind in any case.

Peace,
Bud

 

[large_ghostman]

Like heart attack victims etc and the paddles they use on you, they use a measurement of Joules. joules is what matters and that can vary with skin resistance blah blah blah, or simply watch the video for a great explanation

 

[hyedenny]

[QUOTE="Colin, post: 1300305, member: 7894 "[This current] is causing more damage because it is splitting the water surrounding the button battery and forming hydroxide, which is an ingredient in lye," .[/QUOTE]

Either you COMPLETLY misunderstood the "report" or the report is severely flawed. If there was any "hydroxide formed" it wasn't from the electrolysis of water. Also, hydroxide is not an "ingredient" in lye. Furthermore, any small amount of hydroxide formed from anything in the stomach would be immediately neutralized by stomach acid.
Sheesh! Don't argue something you don't understand!

 

[hyedenny]

"This passes into whatever tissue is nearby, including the aorta or the trachea.

That would also be an interesting trick. Add physiology to chemistry on your list of subjects to brush up on!

 

[Superdat]

well if you watched the video and the bit i put about the title being a little misleading, you would realize it was debunking the myth of its the amps not the volts. personally 30V DC is about my limit before i get careful, i can feel 30V easily but i have YOUNG FRESH skin.

1000V us perfectly safe if you treat it with respect and know what your doing. Look at Derstrom that nutter plays with Tesla coils!

One of the few advantages of being old, high resistance skin!
For something as serious as electrical safety, I don't think it does any harm to repeat the warning. The video is good but a tiny bit complicated as it covers several topics.
Ohm's law is simple(ish) and easy to apply. I offered an alternative explanation, it doesn't mean I thought yours wasn't any good.
Joules is just a unit used to express electrical power, Power = Amps x Volts. A joule is a flow of 1 watt per second.

Oh one more, to answer the OPs question the output of a 24v transformer won't kill and under most circumstances won't give even a tiny shock.

 

[large_ghostman]

I wasnt arguing with you superdat, i was talking to several people at once.......i just leave it to them to decide whom i am referring too .

Lye is Sodium Hydroxide, sometimes potassium hydroxide gets called Lye but thats wrong, No idea how a sodium salt would get into a coin cell though let alone make sodium Hydroxide. I would have thought if the battery case had been eaten through by stomach acid, then metal poisoning would have been high on the list of poisons.
Aorta near the stomach yes, but then most people point way too low to the stomach, its just under the diaphragm, the bits where most think the stomach is are actually the intestines.

I am surprised a baby died though, i would have thought it would have been picked up pretty quickly.

Not particularly talking to you superdat, more kind of mulling it all over, sad whatever way you look at it.

 

[Superdat]

np
Alkalae cells contain potasium hydroxide as an electrolyte, it is similar to sodium hydroxide. Maybe that's where to mix up occurred.

 

[large_ghostman]

yeah i mentioned potassium hydroxide getting mixed up. I work with both alot and prefer potassium to sodium hydroxide, Sodium hydroxide pearls are pretty nasty to work with. I get 25KG bags of it, pouring them into plastic lined seal able drums is not fun. I used to wear wellies but a few pellets down the sides soon changes that!! Now i wear the non nylon thick chest waders with built in wellies lol.

Down side to potassium hydroxide is it deteriorates alot quicker, and the purity is all over the place, as well as water content. Tip of the day.......

If you got dishwasher tablets that etch glass until it goes opaque, get a plastic tub without a lid and bury the dish or whatever in sodium hydroxide, leave a few weeks until you have a carbonate crust and wash off. your glass is good as new and crystal clear.
Cant imagine the pain that baby must have been in from that.

 

[large_ghostman]

Faraday cells use sulphuric acid on paper as electrolyte, they fizz and crackle , awesome sound .

 

[Elerion]

Possibly it's just the manufacturer 'covering themselves' - rather like toys for babies having labels saying 'unsuitable for children under 5'.

Still, strange. Just for frequency measurement? The warning ( input voltage < 30V ) is not on any other section of the manual, just frequency. Good meters from main brands don't have such warnings.
Could it be something regarding particular flaws of some meters?

the question arises because I need a new meter, and I want it to be safe for high voltages. The one I'm talking about is around 100€/$. Not cheap. I don't mind spending a little bit more if necessary.

 

[large_ghostman]

What voltage you going to be working on? Alot of probes will be rated well under the meter rating. I had a fluke and the probes were good for 1000V. my Tenma the probes are good for 600V. My £50 maplin special the probes have no rating but I wouldnt go past 240V household mains with them.

If your mainly working on non industrial voltages then most meters in that price range should be ok, if your stepping up to three phase etc why take a chance? get a fluke meter and probes that wont wear easily.

NONE of the meters I ever seen have a go back button, so dead is dead. Also get nice sharp points if you doing pcb work, really frustrating getting through solder mask with crap tips

 

[Nigel Goodwin]

Still, strange. Just for frequency measurement? The warning ( input voltage < 30V ) is not on any other section of the manual, just frequency.

Possibly the frequency input is only designed to accept such a level?, and exceeding it could damage the meter - so not a 'safety' issue at all (apart from the safety of the meter ).

 

[Elerion]

What voltage you going to be working on?

Oh, I meant 220 VAC and maybe 300 VDC. Not industrial. But not safe voltages either. Tenma seem great meters for the money. I was also looking for RS232 for programatically data logging, and Fluke and most first-class brands are quite expensive.

Possibly the frequency input is only designed to accept such a level?, and exceeding it could damage the meter

Doesn't seem so. The manual says "To avoid personal injury,..."

 

[large_ghostman]

I am ecstatic with my Tenma, rubberized case has taken abuse and has never been calibrated but is checked now and then against a 7 digit meter and is bang on. Really my favorite meter. I got the 72-7730 just checked the probes and they are cat 3 1KV at 10Amps on them. You also get crock clips that screw onto the main probes etc, the hertz function also seems spot on. They are a 20,000 count meter and true RMS. I got a few meters but this was second hand cheap on ebay, really never regretted buying it.

 

[Elerion]

That exactly is the model I was looking at. What a coincidence.

 

[ChrisP58]

Possibly the frequency input is only designed to accept such a level?, and exceeding it could damage the meter - so not a 'safety' issue at all (apart from the safety of the meter ).

And maybe the meter responds by going into its rapid self disassembly mode.

.......................... (BANG)

 

[large_ghostman]

And maybe the meter responds by going into its rapid self disassembly mode.

.......................... (BANG)

A good example of bad marketing, how many companies actually big up this feature on equipment?? Most I have seen tend to play it down if anything, some even actively go against it with Auto self shutdown. Auto shutdown stops self disassembly. Why would you include something that disables something as useful as rapid self disassembly??? Bad sales and marketing if you ask me .

I am still searching for a market for 'magic smoke', I have collected a fair bit lately!! But no one seems to want it , I would try selling it on ebay but the fees lately are getting silly for selling.