How dangerous is 150V - 170V DC?

[Thomas Kummer]

I’m very reckless when it comes to my Nixie projects. I’ve shocked myself with 150 - 170V DC more times than I care to admit, and every time I’ve done it, the shock isn’t that bad. However, every time I’ve done it, my hands have been dry, and there’s been a series resistor somewhere in the circuit. I’ve been tazed before, and the Nixie 150-170V is no where near as bad. Is it the resistors that have saved me, and I should thank my lucky stars that they were there? Or, is it the fact that 150-170V DC isn’t as dangerous as everyone makes it out to be? I mean either way I know I should be more careful. I guess what I’m getting at is what are the chances of me accidentally doing any significant harm to myself from a Nixie project?

[Paul Andrews]

The following is not in any way advice;

This is what I have heard; The heart can be stopped by a few mA at 9V. Applying that to the skin will not get it to the heart because the skin is a good insulator. You need enough voltage to break down that resistance, or there needs to be a physical break in the skin. In addition current needs to flow across the heart, in other words it needs to enter on one side and leave on the other. You need to make a circuit with your body, this is could be done by holding on to the HV with one hand, and a grounded connection with the other. One reason HV can be dangerous is that it can break down materials that would normally act as an insulator, making it more likely that the circuit can be completed.

You will notice that birds don’t drop dead when the perch on HV cables. That’s because theirs nowhere for the current to flow.

[Paul Andrews]

Ugh. Autocomplete massacred that last paragraph.

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[Tidak Ada]

It's not the voltage that causes death the, but the current!
Remember an electric fence for cattle has a voltage of several kV, whereas the current is limited to a few milliamps. In general a current above 10 mA is considered as deadly. Lower currents are painful, unpleasant or symptomless.
The strength of the current is depends highly of the resistance of the path it follows. Here in Netherlands the mains voltage is 230V, what results in peaks of 400V at the top of the sine. If you stand in leather shoes on a wooden floor it gives a very unpleasant feeling, that gives a muscle contraction that lets you mostly to 'untouch' the contact the wire. But in case you have sweaty fingers and naked feet, it may be deadly.
In my working life I was involved in bio-physical research on smooth muscle. There was a strip of muscle placed in a bath with a physiological solution (Ringer's) between two electrodes for stimulation. The current pulses we needed to activate the sample where in the range of several amperes! The main of the current was lead trough the Ringer's solution that functioned as a 'shunt'!!

Once, I made an unintended contact between my upper lip and a scope CRT under 800V, but a current limited by the EY50 diode to a few mA's, I survived, but was ferry impressed!

Anyhow, it is important to AVOID contact with voltages over 30 Volts, the voltage was used in 'farm radio's' in the US.

eric

-----Oorspronkelijk bericht-----
Van: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] Namens Paul Andrews
Verzonden: vrijdag 1 februari 2019 12:16
Aan: neoni...@googlegroups.com
Onderwerp: Re: [neonixie-l] How dangerous is 150V - 170V DC?

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[J Forbes]

I haven't been shocked by high voltage for a few decades, as far as I can recall. I got zapped by a car ignition system when I was young, a few times, and have since learned how to avoid that--even though I regularly work on older cars. When we were young and playing with TV sets, I recall my brother getting zapped by the residual charge in the envelope of the CRT in a decent sized black and white TV set. The operating voltage was in the range of 10-20 kV, but there's no way of knowing how much was left, or how much current was available. He got a jolt, but didn't get hurt. It was a good lesson for me, I have been really careful around that stuff since, and yes, I have been inside older monitors and TVs many times in the past decades. We had an electric fence here to keep the horses in for the past 20+ years, finally the horses all went away last year, so the fence is gone now. I managed to never get shocked by it, perhaps I just have developed a very strong aversion to shocks, and am extra careful.

High voltage supplies on nixie equipment is designed to provide very little current, and this is probably why you've been fine so far, with your educational shocks. I suggest you slow down and be more careful and deliberate around high voltage--it can kill you, you know.

[gregebert]

Here is a link I found : https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html

The fatal current range is 100-200mA . How they determined this is probably an ethical question.

As you said, having series resistance is what can save you, unless you touch the other side, such as across a capacitor, then you are unprotected.

Skin-resistance varies wildly; I measured my dry skin resistance between 3 and 8 megs

Wet skin resistance was 300-600K

I would NOT rely on those numbers, because as I measured it the value wasnt stable, even if I tried gripping the leads tightly.

If your design is isolated, just be sure never to touch more than 1 circuit point. Remember that any test equipment (such as a scope) connected to your circuit will usually adda path to ground, which means your circuit is NOT isolated anymore.

If your circuit is hot, use an isolation transformer. But beware that connecting any grounded test equipment will undo the benefit of isolation.

[alb.001 alb.001]

I was taught that anything over about 40 volts  either AC or DC  should be avoided.   Saying that I have been zapped by the 340 volts of a camera flash capacitor strong enough to make me jump  but watched in fascination as I drew a spark from cold cathode power supply to my finger tip  which was probably over 1000 volts but high frequency and low current.   As others have said,  your skin resistance varies all over depending on your age, emotions, relative humidity age etc etc  , so the chance of drawing a significant voltage and current is not predictable.  I always avoid contact with anything over 12 volts just in case.  there is always a possibility of electrocution and we all need to be careful.

Phil B.

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[David Forbes]

I designed my Nixie watches with very small capacitors in the voltage tripler, to minimize the danger. Nixie tubes don't mind having many volts of ripple in the power. 

On Fri, Feb 1, 2019, 1:19 AM Thomas Kummer <tmkumm...@gmail.com wrote:

I’m very reckless when it comes to my Nixie projects. I’ve shocked myself with 150 - 170V DC more times than I care to admit, and every time I’ve done it, the shock isn’t that bad. However, every time I’ve done it, my hands have been dry, and there’s been a series resistor somewhere in the circuit. I’ve been tazed before, and the Nixie 150-170V is no where near as bad. Is it the resistors that have saved me, and I should thank my lucky stars that they were there? Or, is it the fact that 150-170V DC isn’t as dangerous as everyone makes it out to be? I mean either way I know I should be more careful. I guess what I’m getting at is what are the chances of me accidentally doing any significant  harm to myself from a Nixie project?

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[Bill van Dijk]

I once worked with an old fellow who was in charge of the company’s small equipment. We never went near him when he had a small engine running. His favorite prank was to grab the top of the sparkplug (which did not appear to faze him at all) and then grab any unsuspecting victim in reach. Myself, I never remove the 115V while doing minor repairs (such as replacing an outlet or switch etc.). Touching the 115V does not bother me enough to justify the effort. The zap I got from a (disconnected) 27” color TV did get my immediate attention though. One facility I remember that was designated as a sensitive (very damp) area had only 42V AC outlets for small appliances. Anything with higher demand had to be moved out (that was prior to the invention of battery tools).

 

It seems different people have different tolerances, possibly something to do with skin types and conditions. Safety rules are therefore based on the lowest common denominator.

 

Bill

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[Thomas Kummer]

Thanks for the insight. It is good to know that I probably won’t die from my own stupidity. That being said I will definitely be more careful. I haven’t shocked myself yet today, so that’s an okay start.

[Bill van Dijk]

To put it in some perspective, yes, high voltage is not a safe thing. How unsafe is it? How many people work with these items that "can kill" you? How often do you hear of someone getting killed by their amp, TV, or whatever? If nothing else, we should know of a few on this group?

Be safe, but not paranoid.

Bill

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Thomas Kummer
Sent: Friday, February 01, 2019 6:55 PM
To: neonixie-l <neoni...@googlegroups.com>
Subject: [neonixie-l] How dangerous is 150V - 170V DC?

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[Thomas Kummer]

That’s definitely a good way of putting it.

Sent from my iPhone

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[Richard Arndt]

I will convey a story my engineering manager once told me back in the 70's.  He had a friend who wanted to measure his internal body resistance.  He did so by sticking a pin through the skin on both the right and left hand, then used a VOM (vacuum tube volt-ohm meter) to measure the resistance.  He killed himself.  I understand that once past the skin your body resistance, depending on placement, is 150-300 ohms.  A 9 volt battery across the tongue is quite adventurous and harmless, but I would not try it across the heart (just do ohms law)!  My father was ocean fishing with some buddies when a storm came.  They held onto the boat center console rails and were receiving a challenging tingle from the 12v battery somehow.  Salt water is highly conductive!  Having played in the field of radio transceivers since my youth... I recognize how carelessness can kill.  Fortunately I am still here.  My experience is to stay below 30 volts peak AC/DC peak, when handling with your dry hands.  And I don't temp HV fate just by putting one hand behind my back :-) ... instead turn it off and discharge it first.

[Bill Notfaded]

I think Eric aka Tidak hit the nail on the head... it's not so much the voltage as the amperage that kills you.  I=V/R  You can plug the variables into ohm's law and figure it out pretty easily.  With high resistance even 170V doesn't equal many amps.  I think it's all about potentially how many electrons can flow (voltage) and how easily they are flowing (resistance).

[johnk]

I was involved in the testing of Residual Current Detector designs in the ‘90s. I know that you are discussing the DC at present but you guys also play with AC.

When it comes to a shock the path of the current is very important.

Research the topic a bit. AC and DC.  It is surprisingly complex.

 

While you are at it look up what this guy did…

https://ethw.org/Oral-History:Gottfried_Biegelmeier

 

From the RCD era I have his papers somewhere AND a video of him him a bathtub electrocuting himself –well, shocking anyway for you purists.

I wonder if it is on youtube or the web somewhere?

 

HMM, start with this one.

https://www.youtube.com/watch?v=08r27LnLHCM

 

 

And because we are discussing shocks… I must take this chance [as always] to say that Edison was a lout and should have been electrocuted.

For the elephant, let alone the rest of his atrocities.

 

 

John K

Australia

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[Richard Arndt]

Thank you John for that very interesting read.  

I have explored technical papers to gain some understanding of what is dangerous, since I was doing contract work developing a Galvanic Vestibular Stimulator.  Of course, I was the first guinea pig to test my own device, but it was nothing like this guy Gottfried involuntarily jumping off his seat while voluntarily subjecting himself to significant shocks !!!  No thank you :-)

Rich

[Grahame]

Try this one ... about 45 seconds in...

https://www.youtube.com/watch?v=iDJp2tHmEQo

On 10/03/2019 15:16, Richard Arndt wrote:
> ... guy Gottfried involuntarily jumping off his seat while voluntarily

[gregebert]

I just did a quick project because I needed a bigger isolation transformer, and perhaps an excuse to do another project.

The transformer is big and heavy, at least 50 pounds, so I put the electronic stuff in a metal ammo box.

The multicolor display I used has line voltage, amps, power, and kilowatt hours (with a small reset button) was only 15 USD.

In the photo, the 8.08 amp load is my shop vac, not a nixie clock !! I measured leakage current around 100uA, which is safe enough for lab work.

If your projects use live voltage from the mains, play it safe and use an isolation transformer.

If anyone is near Portland, Oregon and wants my extra 20 amp isolation transformer, its yours for free if you pick it up and haul away.

[Robert G. Schaffrath]

I am 57 now and during my younger years I have been shocked by approximately 600 VDC from a charged filter capacitor in an old tube amplifier. I had just powered off the unit and had my hand on the metal chassis. My needle nose pliers hit the positive on the capacitor and the jolt was so strong my chest muscles contracted and I wound up throwing the pliers across the basement with quite a bit of force. Still have the 750 VAC transformer from that beast. On the AC side, I have been shocked by 10,000 VAC from an oil burner transformer and 15,000 VAC from a large neon sign transformer. All basically lucky situations where I was thrown clear from the source.

As for isolation transformers, when I need quick 120 VAC isolation source I take two old 12.6 VAC 2 A transformers that I have and run them back-to-back. First transformers steps down to 12.6 VAC and the second one run backwards takes the 12.6 VAC and outputs 120 VAC. Obviously for more power I would have to go with a true isolation transformer but this works in a jiffy for the low power draw circuits I play with.

On Friday, February 1, 2019 at 3:19:42 AM UTC-5, Thomas Kummer wrote:

[gregebert]

Given my age (I'm approaching 60), I'm not taking any chances getting shocked; one wrong zap and my heart is toasted. I usually take more precautions than reasonable, and that's probably why I dont recall ever being shocked working on a project. It's the everyday things (lawnmower, fish tank)  that got me  zapped a few times over the years.

[John Smout]

I am 67 and I regularly get shocks from various nixie supplies I forget to care about. I think it keeps me young, but what do I know? My wife takes a dimmer view of getting shocks from my work bench. A good belt from her is far worse though - have you seen her right-hander?

John S

On 28/10/2019 17:10, gregebert wrote:

Given my age (I'm approaching 60), I'm not taking any chances getting shocked; one wrong zap and my heart is toasted. I usually take more precautions than reasonable, and that's probably why I dont recall ever being shocked working on a project. It's the everyday things (lawnmower, fish tank)  that got me  zapped a few times over the years.

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[Mac Doktor]

On Oct 28, 2019, at 11:49 AM, Robert G. Schaffrath <robert.s...@gmail.com> wrote:

On the AC side, I have been shocked by 10,000 VAC from an oil burner transformer and 15,000 VAC from a large neon sign transformer. All basically lucky situations where I was thrown clear from the source.

In High School a friend of mine accidentally grabbed both wires of a furnace transformer. I wasn't there at the time but the witness told me it was pretty scary.

I had both terminals of a photoflash cap touch the palm of my hand once. Ouch.

The only other HV sources I've been zapped by several times are Helium-Neon laser power supplies. They have a really nice snap.

Terry Bowman, KA4HJH
"The Mac Doctor"

Male voice: "That accident over in Red Sector L destroyed another 63 personnel, giving them a total of 242 lost to our 195. Keep up the good work and prevent accidents. This shift is concluded."—THX 1138

[Charles MacDonald]

On 2019-02-01 3:19 a.m., Thomas Kummer wrote:
> Or, is it the fact that 150-170V DC isn’t as dangerous as everyone makes it out to be? I mean either way I know I should be more careful. I guess what I’m getting at is what are the chances of me accidentally doing any significant harm to myself from a Nixie project?
>

it is not the Voltage that gets you but the current. !!!

dry hands and series resistance can keep the current down to levels that
you can survive...

--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

[Bill Notfaded]

I think it's the current that can really kill you not so much the volts.  Static electricity can be hundreds of thousands of volts... But there isn't much current there.  Take 4 or 5 amps at almost any voltage and it can pretty easily kill you.

Bill

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[HuggerMugger]

I think the main problem with electrickery is that AC may get your heart into fibrillation, whereas DC causes severe burning. A heart that is running wild may be easier to get back to normal operation than a heart that is barbequed.

 

/Magnus

 

From: Bill Notfaded

Sent: Tuesday, October 29, 2019 10:25 PM

To: neonixie-l

Subject: Re: [neonixie-l] How dangerous is 150V - 170V DC?

 

I think it's the current that can really kill you not so much the volts.  Static electricity can be hundreds of thousands of volts... But there isn't much current there.  Take 4 or 5 amps at almost any voltage and it can pretty easily kill you.

 

Bill

 

On Mon, Oct 28, 2019, 7:21 PM Charles MacDonald <cm...@zeusprune.ca> wrote:

On 2019-02-01 3:19 a.m., Thomas Kummer wrote:
>  Or, is it the fact that 150-170V DC isn’t as dangerous as everyone makes it out to be? I mean either way I know I should be more careful. I guess what I’m getting at is what are the chances of me accidentally doing any significant  harm to myself from a Nixie project?
>

it is not the Voltage that gets you but the current. !!!

dry hands and series resistance can keep the current down to levels that
you can survive...

--
Charles MacDonald                 Stittsville Ontario
cm...@zeusprune.ca              Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

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Virusfritt. www.avast.com

[Mac Doktor]

On Oct 29, 2019, at 5:42 PM, HuggerMugger <hugger...@pastisch.se> wrote:

I think the main problem with electrickery is that AC may get your heart into fibrillation, whereas DC causes severe burning. A heart that is running wild may be easier to get back to normal operation than a heart that is barbequed.

RF burns are the worst. Tesla put thimbles on his fingers.

On Oct 28, 2019, at 10:21 PM, Charles MacDonald <cm...@zeusprune.ca> wrote:

dry hands and series resistance can keep the current down to levels that you can survive...

Keep your left hand in your back pocket.

Terry Bowman, KA4HJH
"The Mac Doctor"

"I don't even gargle Listerine. I heard it kills germs on contact and I don't like the idea of somethin' dyin' in my mouth."—Jim Stafford

[Robert G. Schaffrath]

Indeed. In the earlier days of me being licensed, my HF rig zapped me a few times due to problematic grounding issues. Seemed to have the most problems on 75m and 10m.

[Gary Gaspar]

it is the connection & how good AC DC it does not matter A good ground A good connection you can be toast. Saw the smoke come from my finger 1 leg 480 ac my other hand was on a long pipe not grounded to well. 480 ac on wet concrete many times was a maintenance supervisor / electrician. One nick & some copper showing when I was pulling out a long wire which was LIVE many wires could not turn everything off almost cost me. Clock on my wrist showed me time was ticking lost connection on pipe when my legs buckled.  

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[Mac Doktor]

On Oct 30, 2019, at 5:55 PM, Gary Gaspar <majr...@gmail.com> wrote:

One nick & some copper showing when I was pulling out a long wire which was LIVE many wires could not turn everything off almost cost me. Clock on my wrist showed me time was ticking lost connection on pipe when my legs buckled.  

I'd quote the Monty Python "Four Yorkshiremen" sketch here but this is too scary. I was drilling out a hole to run the wires for a satellite dish (the old 10'/3m kind) and suddenly realized I was right next to where the mains came into the basement. It was nothing but a piece of heavy gauge romex with the flexible metal sheath run through a small hole.

I don't think it would meet code today.

[the quote is "luxury"]

Terry Bowman, KA4HJH
"The Mac Doctor"

Nately: "...it's better to die on your feet, than to live on your knees."
Old Man: "You have it backwards: it is better to live on your feet, than to die on your knees."—Catch-22