General > General Technical Chat
Can a neon sign transformer with an output of 12000V and 30mA kill you?
BrianHG:
Styropyro has thoroughly described the situation here:
Someone:
--- Quote from: BrianHG on May 27, 2023, 12:36:20 am ---Styropyro has thoroughly described the situation here:
--- End quote ---
Except its not thorough or complete:
https://www.eevblog.com/forum/chat/is-it-the-volts-or-amps-that-kill-(video-from-styropyro)/
and that "information" is in the most infuriating format of an advertisement supported video so people cant easily skim/quote/refer to specifics. There is much more to electrical safety or human responses to electrical current. We already had a comment covering most of that in this thread:
https://www.eevblog.com/forum/chat/can-a-neon-sign-transformer-with-an-output-of-12000v-and-30ma-kill-you/msg857194/#msg857194
--- Quote from: ejeffrey on May 26, 2023, 11:12:45 pm ---
--- Quote from: Florin on February 01, 2016, 08:41:01 pm ---But, for example, if a transformer will be limited to, let's say, 1 - 10 mA or even lower it will be safe regardless of the output voltage?
--- End quote ---
1 milliamp AC should be relatively safe even if the open circuit voltage is high. 10 mA is still enough to cause a painful shock but unlikely to kill a person unless they have a underlying heart condition. I still would treat it as dangerous, and who wants to find out that they have an underlying heart condition when an HV transformer shocks them?
With HVDC supplies you also have to worry that it might have a large output capacitor that can store significant energy.
--- End quote ---
Again, in this thread there are several examples of outcomes that will kill you well below the currents that can cause a heart to stop so its not the best measure of potential lethality. As you expand upon with capacitances, that does not seem to reach people on this forum who just carry on regardless:
https://www.eevblog.com/forum/reviews/completely-non-sketchy-mini-high-voltage-transistor-tester-(emeco)/
Small, handheld, "limited" output current, already dangerous, but then turned up to 11.
CatalinaWOW:
So to directly answer the OPs question. YES! It can. It may not. In fact you may survive several exposures.
Perhaps an analogy would make things clearer. Can you define a speed at which a motorcar is absolutely safe? Not really. Imagine something trapped between a wall and a motorcar going 0.1 miles/hour towards the wall. Even at this speed a fatality in this case is not unlikely. As the speed increases the special conditions required to cause a fatality become less and less special. But people have survived operating motorcars at speeds over 400 mph. And even survived wrecks. But the percentage of people who have been killed while driving at speeds over 400 mph becomes pretty substantial.
It is well worthwhile exercising extreme caution when operating the transformer identified by the OP. There are a number of minor mistakes which can be made which would result in a very painful session and possibly even death.
Psi:
It definitely could kill yes.
Due to the much higher voltage it's a lot more likely to pump the full 30mA through your body than sticking your finger in a 230V power point where your body may or may not have a good path to ground.
On the other hand, 30mA is much less than the 20A available to flow from sticking your finger in a power point if your body has a good connection to ground.
David Hess:
The output of a neon sign transformer can definitely kill you, but maybe I got lucky.
When I was in high school, I accidentally picked up my 15 kilovolt 30 milliamp neon sign transformer by the terminals and insulators while it was plugged in. I got as far as lifting it before I consciously set it down and released it rather than dropping or throwing it. The total time was a couple seconds. After that I sat against the wall for a couple minutes sweating.
I have experienced 120 volt AC line voltage a couple of times and I would say that it was worse, but of course then the impedance is lower and the current is higher.
Another time I was working with a 1000 volt DC power supply that I had built for a strobe and managed to short the output out from my finger tip to my elbow while standing on an aluminum ladder. That knocked me off the ladder and across the concrete floor. I had a pair of burn marks on the tip of my finger and my elbow, and my whole arm hurt for days. In this case the power supply had 10s of microfarads of capacitance which was way too much, lesson learned.
--- Quote from: dexters_lab on February 01, 2016, 09:12:51 pm ---safe? i would not call it safe by any means, even a few mA at 12kv will burn you at least
--- End quote ---
I was not burned but there was no sustained arc.
--- Quote from: uncle_bob on February 02, 2016, 12:41:22 am ---30 ma at a couple of KV (DC or low freq AC) will knock you across the room from the muscle contraction.(no it does not knock you, your muscles knock you, the result is the same and it hurts). Yes I have empirical data ...
--- End quote ---
No, I have experienced both and the current limited AC will not. Even 1000 volts of DC can knock you across the room, and off of a ladder in my case, if it has a moderate amount of capacitance or low enough impedance.
--- Quote from: f4eru on February 02, 2016, 05:39:10 am ---By the way, if a transformer is marked "30mA", this is a continuous rating. In the case of a short circuit, (for example through the "low" resistance of an human), it will happily supply 10-50x more -> 300mA to 1,5A.
To these lethal effects of electric current, at that high voltages and high current, the heat of the arc will burn flesh.
--- End quote ---
The output current of a neon sign transformers is deliberately limited by the transformer's impedance. They could certainly burn flesh if an arc is present, however inadvertent contact will likely result in either immediate recoil or intimate contact. In either case an arc is not present for long enough to burn.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version