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I was watching this YouTube video. The content maker simply declared that 200/300 volts DC is safe to touch.

I think the capacitor used in that circuit is limiting the current. That's why nothing is happening to him.

I have seen my friend to get injured by touching the supply line of 400 volts DC generator in lab.

My question is - Is it really to safe to touch any DC supply (200- 300 volts) without considering line impedance or the maximum current that can be provided by the source?

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    \$\begingroup\$ Please note that ElectroBOOM is very good at showing what not to do. Also note that despite his clumsy act, he knows very well what he's doing and how not to die from his stunts. Enjoy his content, but please don't recreate any of his experiments that use voltages in excess of, say, 25V. \$\endgroup\$
    – marcelm
    Commented May 21, 2020 at 14:11
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    \$\begingroup\$ ElectroBOOM is a talented entertainer. After seeing a sword swallower at the circus you should not go home and stick a knife down your throat. \$\endgroup\$
    – JonathanZ
    Commented May 21, 2020 at 15:04
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    \$\begingroup\$ "The content maker simply declared that 200/300 volts DC is safe to touch." - At what time in the video does he state that? I've rewatched the video, but I've never heard him make that statement. The video is about the pain sensation of AC vs DC (he makes that clear in the first 10 seconds), not about their relative safety. \$\endgroup\$
    – marcelm
    Commented May 21, 2020 at 15:27
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    \$\begingroup\$ Questions on stack exchange sites must stand on their own. It's impossible to tell what this is actually about without watching a video on an external site, hence it does not belong here. As for the question, if you have to ask, don't do it. \$\endgroup\$
    – Chris Stratton
    Commented May 21, 2020 at 15:52
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    \$\begingroup\$ I've watched that video several times now. It never gets old. \$\endgroup\$
    – Robert Harvey
    Commented May 22, 2020 at 21:24

5 Answers 5

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The content maker simply declared that 200/300 volts DC is safe to touch.

He didn't say this anywhere in the video, and he didn't imply it either. In the first few seconds he says:

I want to kick it up a notch and show you at what voltage it hurts over skin

He is just showing "when does it start hurting". That's all.

He has another video of a live demonstration, hooking up multiple car batteries to produce 120V DC and touches them: https://youtu.be/ZxBF7WC0TQk?t=654

He feels it and it hurts, but not nearly as much as 120V AC.

He's not saying DC is always safe. He explains the dangers in a different video where he talks about the relationship between voltage and current in hurting you: https://youtu.be/XDf2nhfxVzg

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    \$\begingroup\$ At 3:23, when he touched the 334V DC, it still hurt him to the point that he couldn't hold his fingers on it. The message there is: 334V DC will hurt you. \$\endgroup\$
    – Gabriel Luci
    Commented May 21, 2020 at 16:12
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    \$\begingroup\$ @SadatRafi I think it's a dangerous over-interpretation. I cannot read it from his stunt video \$\endgroup\$
    – Sebi
    Commented May 21, 2020 at 17:31
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    \$\begingroup\$ Try not to sweat when doing it \$\endgroup\$
    – Dirk Bruere
    Commented May 21, 2020 at 22:32
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    \$\begingroup\$ It's safe only if your skin's resistance holds out. Like what @DirkBruere said, if you start sweating, your hands are wet, or there's something else that allows free lowing current into your body, it'll kill you just the same. In the same sense, electric outlets don't kill you if you walk past them because it couldn't overcome the resistance of air. Lightning, on the other hand, can definitely kill you through air. \$\endgroup\$
    – Nelson
    Commented May 22, 2020 at 6:05
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    \$\begingroup\$ @Sebi To you and me it may be obvious that it is not intended that you should touch 200VDC but you'd be surprised how many people (especially around my neck of the woods) who have the attitude of "he did it and is still alive so I can do it as well" \$\endgroup\$
    – slebetman
    Commented May 22, 2020 at 12:22
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No, most electrical regs class low voltage “safe” as below 50V DC

It is not the max current but where it travels through the body and, also, when in the heart cycle it hits...

So, don’t play.

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    \$\begingroup\$ I think the hazard from DC voltages in the 60V-100V range is not from electrocution, but rather fire. At lower voltages, if e.g. a tiny strand of wire momentarily shorts out a supply, arcing produced thereby would likely be self-extinguishing, but as the voltage increases, so does the potential for a sustained arc. \$\endgroup\$
    – supercat
    Commented May 21, 2020 at 21:00
  • \$\begingroup\$ @supercat the OP was talking a out 200 to 300V not less than 100V... \$\endgroup\$
    – Solar Mike
    Commented May 21, 2020 at 21:05
  • \$\begingroup\$ Does anyone mind explaining the second paragraph/sentence? I'm not a native speaker and can't parse it \$\endgroup\$
    – Sebi
    Commented May 23, 2020 at 15:37
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The linked video at 3:48 reveals something very essential of "teacher's" capabilities. He can output nonsense with quite assuring voice. I do not think he believes himself that human body has capacitance which makes easier for AC voltages than for DC voltages to generate harmful current.

Do not believe him. Even much lower DC voltage can be dangerous. I have seen how a car battery made in about 1 second a screwdriver so hot that it burned its way to user's flesh. 100V or more DC can stop ones heart when a person gets it from hand to hand or from hand to feet. There's no exact voltage limit for this. Someone can stand more than another. The moisture and how tight the contact happens to be effects, too.

Regulation codes for electric works vary. Check which is the limit of extra low voltage (=ELV) where you live. Staying below the limit does not make the voltage safe, but it's used in a court of law when the judge must decide if someone has caused a danger intentionally. Any electric works with higher than ELV voltages can be considered intentional searching for troubles, no matter did a person know that such limit exists or not.

AC causes pain continuously because the current turns forth and back and every pulse disturbs the nerve system. DC hurts that way only when the current starts or stops. But high enough starting pulse can stop one's heart.

"Teacher's" circuit was galvanically connected to mains AC. His touching the DC output could have given a different result if he had accidentally a connection to the ground for example through leather shoes and a concrete floor. Having a rectifier would in that case make no difference.

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    \$\begingroup\$ DC hurts continuously too \$\endgroup\$
    – Ocanath
    Commented May 21, 2020 at 1:26
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    \$\begingroup\$ Dry skin is a pretty good insulator. Even low voltage can produce dangerous amounts of heat when flowing through low resistance, but dry skin resistance is on the order of 100,000 ohms, which would limit heat production to a level far below what the body would be doing on its own. The problem with AC is that nerves and muscles respond to even small changes in current. \$\endgroup\$
    – supercat
    Commented May 21, 2020 at 15:00
  • \$\begingroup\$ "Teacher's circuit was galvanically connected to mains AC." - I suspect his final circuit was connected through an isolation transformer at the very least, allowing him some degree of safety touching the hot lead (assuming the stunt isn't faked more thoroughly). \$\endgroup\$
    – marcelm
    Commented May 21, 2020 at 15:23
  • \$\begingroup\$ There's no need to have anything like shown when one makes entertainment videos like this. It's elementary to generate apparent voltage readings and to keep stuff out of the picture. I wrote: Do not believe! \$\endgroup\$
    – user136077
    Commented May 21, 2020 at 15:29
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    \$\begingroup\$ "I have seen how a car battery made in about 1 second a screwdriver so hot that it burned its way to user's flesh." - That's confusing the issue. The question is talking about electricity hurting you, not heat hurting you. Sure, you shouldn't short your car battery, but you really shouldn't short any battery. \$\endgroup\$
    – Gabriel Luci
    Commented May 21, 2020 at 15:56
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Strictly speaking, voltage won't tell you whether something is safe or unsafe to touch. A Van De Graaff generator can create extremely high voltages, and many are designed specifically to be touched. These won't hurt you because the output current is extremely low. It's actually the current that hurts you, not the voltage. People have died from voltages as small as 42V. I've touched a Van De Graaff generator rated at around 1,500,000V and had no negative effects.

In your specific case, power supplies are generally designed to output a significant amount of electrical current, so I wouldn't recommend touching a power supply rail at any voltage.

Regarding your comment, the capacitor isn't limiting the current. Capacitors limit how fast the voltage can change. When it comes to current, one of the big use cases for capacitors is how they can provide extremely high output currents when they discharge. If anything is limiting the current, it would be a resistor of some sort.

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No, in general it's dangerous to touch 200V-300V DC.

Look at https://en.wikipedia.org/wiki/Extra-low_voltage for details on voltages considered safe to touch by different regulating bodies.

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