Is 5 milliamps at 240 volts dangerous?

[kma]

Quick question, is 5 milliamps at household voltage like 240 dangerous? See many conflicting views on this, official accounts state that on an electric shock chart, 5ma is nowhere near the level needed to cause any damage but some electricians on reddit say with low body resistance even low currents like that are dangerous... And how does a taser stun when its such little current, when 3 milliamps isn't supposed to have that effect...

 

[Baluncore]

Yes, it is dangerous.
People are different.
The path of the current can be different.

 

[berkeman]

Quick question, is 5 milliamps at household voltage like 240 dangerous?

According to the link below, 5mA is marginal. But the practical issue is how are you going to limit that shock current to 5mA? If you have a 240Vrms source like AC Mains and it comes in contact with your body, you will not have any current limiting control over the current that flows. That just depends on the conductivity of the path through the body, which depends on all kinds of things.

It is best to avoid electrical shocks altogether. Even a 9V battery can be felt, if placed across an appropriately low-resistance path through the body, and in fact it can knock you out of your chair if it is applied "incorrectly" (don't ask me how I know this).

Have a look through this reference: https://pressbooks.online.ucf.edu/phy2053bc/chapter/electric-hazards-and-the-human-body/

 

[Drakkith]

It is best to avoid electrical shocks altogether. Even a 9V battery can be felt, if placed across an appropriately low-resistance path through the body, and in fact it can knock you out of your chair if it is applied "incorrectly" (don't ask me how I know this).

Did you lick the terminals again, Berk?

 

[phinds]

And how does a taser stun when its such little current, when 3 milliamps isn't supposed to have that effect...

Uh, you obviously have no idea how many volts it has.

 

[Averagesupernova]

Even a 9V battery can be felt, if placed across an appropriately low-resistance path through the body, and in fact it can knock you out of your chair if it is applied "incorrectly" (don't ask me how I know this).

Some day I would like to hear every story behind all of your "don't ask me how I know..." statements.
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I recall as a youngster I tried something that was rather stupid. Seemingly harmless at the time. I had a 200 in 1 radio shack kit. I was fiddling around with one of the audio oscillator circuits. There was a resistor that could be changed to change the pitch. I was grabbing leads with my fingers to substitute for the resistor, stuff like that. So I stuck one lead between my lips and held the other with my hand. Nothing too surprising there, not much change in pitch compared to hand to hand. Realize this circuit was powered with about 4.5 volts. Knowing a 9 volt battery wouldn't do much to a person's tongue except an unpleasant tingle, I tried that. Same thing, no big surprise. Well, exactly what happened after that I'm not sure but I suspect one lead contacted the wire part of my braces. I was a gangly brace face kid at this point. Quite a jolt. For the brief moment before my hand pulled the leads out everything got dark. I have to assume the muscles in my face contracted and my eyelids went shut.
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My dad has described the feeling of a jolt from an electric fence on top of the head as if someone smacked him over the head with a baseball bat. Years later I happened to get hit with an electric fence jolt on the top of my head and what I noticed was the same sensation of darkness for a split second.

 

[Averagesupernova]

As to the original question about 5 mA, in the US a GFCI outlet is protected at 5mA. So an imbalance of current between hot and neutral at 5mA or greater will trip the device. I'd like to think that it is perfectly safe but as other posters have said, depends on where the current is flowing. A big open wound on my chest while standing with wet bare feet, I would not want current flowing from that wound to my feet. Way too close to the heart.

 

[Tom.G]

I test 9V batteries by touching them on my tongue. If new, I sorta wish I hadn't! After some practice, you get an idea of how much charge is left. Chemical taste when they are leaking.

 

[DaveE]

It could be dangerous, so you should assume it is. This is a case where 'if you have to ask us, you shouldn't mess with it.'

If you really want to know, look into some product safety standards: what the limits are and how they are tested. "EN 60950-1 Information technology equipment – Safety" comes to mind, probably the most cited of the plethora of electrical safety standards. You can search the web for it, it might also start with "IEC", "UL", "CSA" etc. It's the 60950-1 part that matters, they are all the same. It has a limit for accessible parts of equipment of 0.25mA. Although it gets a bit complicated, this is essentially your question. Medical devices for patient contact have much more stringent limits; look for 60601-1 for those.

As an aside, when I had to look into electrical safety for US military products in the 1980s (which, BTW were scarily primitive), their requirement for electrical shock hazards made the point that it isn't just electrocution they cared about. If your shock made someone fall off of a ladder and hit their head, it was a significant hazard.

 

[Rive]

As to the original question about 5 mA, in the US a GFCI outlet is protected at 5mA. ... I'd like to think that it is perfectly safe but as other posters have said, depends on where the current is flowing.

It's considered reasonably safe only since the current supposedly got terminated fast in case a GFCI is involved.

In reality a continuous 5mA current (from some insulation failure) would be a weird thing - either it's not at line voltage (the resistance what sets the current will drop voltage) or it'll not remain 5mA for too long.

 

[Baluncore]

Quick question, is 5 milliamps at household voltage like 240 dangerous?

Quick question, is walking between the two painted solid lines in the middle of a highway dangerous?

 

[Fra]

I think there are two issues with electrical currents in the body.

1) At once extreme is tissue damage ~ internal or external burns, but this takes quite some energy.

2) But long before that at much lower energies the main risk of cardiac arrythmia which is the main issue to start with.

Electrical stimulators for pain shocks in psychology research, can easily output 200V and even up to hundreds of mA - but only for a brief time, usually the order of 0.1-20ms or so. So the total energy is limited. Using surface electrodes the typical skin impedance is 1-20 kOhm. This will not cause any burns, and is "safe", but only if applies on the same side of the body. Electrical stimulator usually have limts on single pulse energy of around 300mJ or so, as per some saftey regulations.

But if applied accross the body, even at low energy, it might increase risks of heart arrythmia, so it's not safe to carelessly apply these voltages across arbitrary body positions.

I know some "tough" electricians with thickened dry skin that check the 230VAC power voltage lines between their fingers (but on the same hand). But with wet hands, it would be worse.

/Fredrik

 

[Tom.G]

This research report seems to indicate that 8mA is enough to effectively have you curl your hand into a grip pose.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582372/

See also these posts:
https://www.physicsforums.com/posts/6259704/
and the one immediately following it:
https://www.physicsforums.com/posts/6259752/

And of course the inevitable Google search:
https://www.google.com/search?hl=en&q=current+required+to+stop+a+heart

Cheers,
Tom

p.s. Unless you have a Doctor standing by with a defibrillator, I recommend you NOT try the experiment!

 

[berkeman]

Thread closed for Moderation...

 

[berkeman]

The OP has not been back since posting their question, but I think that the replies and references supplied should do a good job of answering their question. So I'll close this thread for now. Thanks for all of the good replies.

@kma -- If you still have questions after reading through the thread, send me a Personal Message (PM) so we can discuss whether to re-open this thread.