Is it safe to touch a live AC wire?

cmartinez

Joined Jan 17, 2007
6,991
Is it safe to touch a live AC wire without getting electrical shock, if not, why is the person below not shocked?
View attachment 129281
Taken from the following source: https://www.allaboutcircuits.com/textbook/direct-current/chpt-3/shock-current-path/
It is NEVER safe to touch a live AC wire, period. Your being shocked or not depends on factors already described in the link that you posted. But it's always best not to touch any AC wire for safety reasons, be it live or neutral.
 

djsfantasi

Joined Apr 11, 2010
6,497
I agree with cmartinez

But you might wonder why the post you shared. You have to read the qualifications in the preceding paragraph. The voltage source cannot be grounded! This is important because most AC sources in the environment ARE grounded.
 

wayneh

Joined Sep 9, 2010
16,398
"Safe" means absent of risk, so no. It's not safe until all of the risks are identified and eliminated. As asked, your question does not address all the specific factors that affect risk, so no one can say all the risks have been eliminated.

The article you linked does address some of the issues. The image shows a hypothetical scenario of an isolated (and I mean fully isolated) circuit floating in space, if you will. You can touch such a hypothetical circuit safely because there it no driving force to drive current through your body to ground. There is no path to complete a circuit. But that's a hypothetical scenario. Real scenarios always have some path for current, perhaps just the air around you.
 
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ian field

Joined Oct 27, 2012
6,539

ScottWang

Joined Aug 23, 2012
6,909
When you used the picture from other forums then you can't modify the contents, and leading our members to the wrong direction.

Your picture:


The original picture:


The Ground of High voltage between the Ground of human body has the resistance, but it still has the current flows through between them, so the current flows through from the High voltage to the human body to Ground, and back to the Ground of High voltage and then the human will be shocked.

Edit : sorry for made a mistake.
 

cmartinez

Joined Jan 17, 2007
6,991
When you used the picture from other forums then you can't modify the contents, and leading our members to the wrong direction.

Your picture:


The original picture:


The Ground of High voltage between the Ground of human body has the resistance, but it still has the current flows through between them, so the current flows through from the High voltage to the human body to Ground, and back to the Ground of High voltage and then the human will be shocked.
Scott, the picture posted by the op is there in the link, it has not been altered:

Image00001.jpg
On the other hand, the picture shows a DC source, not an AC one as the op asked. Maybe that's where the confusion comes from. Although this scenario does not consider the human body's inherent capacitance.

EDIT: Adjusted image size for comfort reasons.
 
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ScottWang

Joined Aug 23, 2012
6,909
Scott, the picture posted by the op is there in the link, it has not been altered:

On the other hand, the picture shows a DC source, not an AC one as the op asked. Maybe that's where the confusion comes from. Although this scenario does not consider the human body's inherent capacitance.
cmartinez, thank you.
Before I post it, I checked twice, how come I missed it?
Maybe I'm too tired and haven't recover yet.
 

Thread Starter

Bow Meiler

Joined Jun 19, 2017
5
Not Shock.JPG Shock.JPG
In summary: correct me If I'm wrong, a person touching a live wire regardless whether is AC or DC will not get electrical shock as long there is no return path back to the source.
 

cmartinez

Joined Jan 17, 2007
6,991
Having NO return path protects in a DC circuit. A human has some intrinsic capacitance and that means an AC current will flow if the voltage is high enough.
Yes. And even a DC circuit will cause some current to flow into the body for the same reason. Though only just once.

Again, it's not advisable to touch anything above 24V. Most sources agree that anything above 40V will shock you.
 

takao21203

Joined Apr 28, 2012
3,695
I have recently been touching 240V mains with both hands and it was quite nasty. Survived.

About touching high voltage line, its not safe. The human body has both surface area with corona effects and capacitance and static charge carrying potential.

So if you touch 110kV even suspended in air sparks will zap and probably some continuos current will flow.

The bird will not become electrocuted because its total surface area is quite small. However Im in doubt a large bird probably would see some effect.

You should remember never go near line voltage with your left or both hands (if you have to). And if you have no clearance/permission, stay away from hilgh voltage entirely.
 

MaxHeadRoom

Joined Jul 18, 2013
20,860
The bird will not become electrocuted because its total surface area is quite small. However Im in doubt a large bird probably would see some effect.
.
See a flock of birds on transmission lines, the ones that get electrocuted are usually the ones on or near the tower stand-off insulators.:eek:
Max.
 

ian field

Joined Oct 27, 2012
6,539
Having NO return path protects in a DC circuit. A human has some intrinsic capacitance and that means an AC current will flow if the voltage is high enough.
I don't have enough capacitance to notice much at 230V 50Hz - but several kV at TV horizontal frequency is a different matter.
 

tcmtech

Joined Nov 4, 2013
2,867
Yes you can touch a live line without harm if the conditions are right.

Personally I rarely shut off 120 vAC lines when working on them unless there is a fair chance to have a short circuit if I slip up, but that me.

Sure, there's' a chance it could kill me but then so is there with tripping over the cat in the middle of the night too but I don't avoid the cat or getting up at night just because of a very low probability what-if something did happen.
 
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