If you touch just one phase.. - Page 2 - Electronic Circuits Projects Diagrams Free

tcmtech · 4th July 2009, 10:14 PM

A buddy of mine has had several cats do the live wire dance on his pole transformer for his farm over the years.

They come down just like that dummy on the train did! Crispy and flaming!

BrownOut · 4th July 2009, 10:17 PM

Quote:

Originally Posted by tcmtech

A buddy of mine has had several cats do the live wire dance on his pole transformer for his farm over the years.

They come down just like that dummy on the train did! Crispy and flaming!

Welcome back!

smanches · 4th July 2009, 10:19 PM

I agree with crutschow. My uncle worked as an electrician at the mines where they run 100KV. When I was a kid I asked him why the birds didn't get electrocuted, he went on to explain they weren't grounded. I do remember asking him if I could hang from the wires, and he explained that because we're so much larger than the birds, the capacitance of our bodies could still be enough to kill us, even not being grounded.

And then a college kid proved it to us a number of years later. Stupid fraternity dare. And that was only on the normal street wires, which I think are only 4KV.

tcmtech · 4th July 2009, 10:37 PM

One of my college professors had a video of a guy in a bucket truck in some foreign country that took a hit off a 69 Kv main line while trying to hook up an illegal substation for a small village.
An uninsulated truck and and apparently a fairly conductive hot stick (broom handle) was used!

He basically exploded, the fiberglass bucket bursts into flames, the truck tires explode, the boom operator gets severe burns from the hydraulic system when it blows up and shoots flaming oil all over the truck. The operator did manage to jump free and run away while the whole truck burned up in a matter of a few minutes. By the time the emergency crews get there the whole truck had burned up.

They said the bucket guy was half his regular weight when they buried him.

Hero999 · 4th July 2009, 11:59 PM

I doubt you can be electrocuted by touching a single phase of an HT line, if you're not grounded or connected to a huge metallic object.

Assuming 100pF in series with 1k (the standard human body model) and the US power line frequency of 60Hz. We can ignore the 1k for now because it'll be insignifcant compared to the capacitance at 60Hz.

$Z = \frac{1}{2\pi FC}= \frac{1}{2\pi \times 60 \times 100\times 10^{-12}}= 26.53 \times 10^6 \Omega$

26.5M is one hell of a high impedance!

For a 100kV line:

$I = {100 \times 10^3 }\times {26.53 \times 10^6} = 3.77 \times 10^{-3}A$

3.8mA might give you a small shock but it certainly won't kill you, more likely than not you'll just swear.

What about the power dissipation? Will 3.77mA at 100kV burn you? No, it won't.

Why?

Because you only need to take the current and resistance into account, the rest is just reactive impedance.

$P = I^2 R = (3.77 \times 10^{-3})^2 \times 1000 = 14.21 \times 10^{-3}W$

14.21mW isn't going to burn you.

In the instances you're talking about the electricity was finding a path to earth, one way or another. The fibre glass bucket wouldn't provide good enough insulation, a spark could easily track down the side. The helicopter is a huge metalic object with a much higher capacitance than a human so a lethal current could flow.

Andy1845c · 5th July 2009, 04:40 AM

TCMs story reminds me of this video. Maybe some of you have seen it. Its a testament to the danger of powerlines.

YouTube - Crane hits power line

Mr RB · 5th July 2009, 02:36 PM

I think some of the difference is due to the difference between 110v ac and 240v ac. I've had numerous shocks from both (and even once from 415v ac which HURTS) and 110v barely rates a mention in pain terms. I forget most of you guys only get the chance to be zapped with 110v, you miss all the fun.

240v will give a nasty tingle even when you are insulated, especially if you have extra capacitance elsewhere on your body like a sweaty work shirt etc.

Pommie · 5th July 2009, 03:24 PM

My experience was in the UK and 230V phase to neutral - 440 phase to phase. I have had many shocks at 240V as I am sure most (older) UK posters here have. I have never experiences 440V as that requires contacting two phases. I did, unfortunately, have a Friend that did experience contact with two phases and I attended his funeral with his wife and daughter. He was in a lift motor room when an apprentice turned the power back on - I'm guessing that apprentice will never make that mistake again. For anyone curious, this was 11 years ago.

Mike.

Hero999 · 5th July 2009, 03:30 PM

Did the apprentice get manslaughter?

whiz115 · 5th July 2009, 03:32 PM

if you need to close circuit with the earth so you can get electrocuted then why when you accidentaly touch the live in the mains you get a nasty shock?!

KMoffett · 5th July 2009, 04:11 PM

You won't...unless some other part of your body/clothes(sweaty) is providing a resistive or large capacitive path to ground.

Ken

**Nigel Goodwin** · 5th July 2009, 04:12 PM

Quote:

Originally Posted by Pommie

My experience was in the UK and 230V phase to neutral - 440 phase to phase. I have had many shocks at 240V as I am sure most (older) UK posters here have.

The UK mains is still 240V - it's only nominally 230V - it was 'standardised' a number of years back to 230V for all the EU. However, nothing changed - except the design of appliances, the UK is still 240V, the rest of Europe 220V, but both are nominally 230V, and appliances are designed to work on 230V +/- a certain percentage, which covers both 240V and 220V.

whiz115 · 5th July 2009, 04:25 PM

Quote:

Originally Posted by KMoffett

You won't...unless some other part of your body/clothes(sweaty) is providing a resistive or large capacitive path to ground.

Ken

i've seen people electrocuted just putting their finger somewhere they shouldn't... in fact they were standing up and touching nothing else also whearing athletic shoes...which have rubber.

btw how stun guns work?

KMoffett · 5th July 2009, 04:44 PM

Quote:

Originally Posted by whiz115

i've seen people electrocuted just putting their finger somewhere they shouldn't... in fact they were standing up and touching nothing else also whearing athletic shoes...which have rubber.

btw how stun guns work?

Can you describe the details of "putting their finger somewhere they shouldn't"? If their finger touches a active conductor and another part of their finger/hand touches a neutral conductor/grounded surface they can get a shock. This is describing low frequency power (i.e. 50/60Hz). If it were a high frequency power source like inside a CRT HV circuit, the conductive path to ground/common can be capacitive...and does not to make a direct contact to the other conductor.

Stun guns/tazers have two conductors in/on you. Well I think the high frequency arc in a stun gun can actually arc to you, through an ionized air path, without actually making contact.

ken

Hero999 · 5th July 2009, 04:55 PM

I doubt they were just holding the live wire, probably live and neutral or live and an earth or an earthed object.

When you mean electrocuted do you mean killed or just a bad shock?

I've seen people being shocked but never electrocuted.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar
Title	Starter	Forum	Replies	Latest
Phase shift - Phase Angle	windozeuser	General Electronics Chat	20	20th March 2009 10:39 AM
Phase Sequence or Phase Present	neelam29	General Electronics Chat	7	23rd May 2007 11:25 AM
Three Phase Versus Single Phase For EV	fzn10	General Electronics Chat	4	31st July 2006 09:39 AM
3 phase to single phase	eyeofthefly	Electronic Projects Design/Ideas/Reviews	34	14th November 2003 04:17 PM
converting 3 phase motor to single phase	norberto fines	Electronic Projects Design/Ideas/Reviews	6	2nd September 2003 11:21 PM

4th July 2009, 10:14 PM	#16
tcmtech	A buddy of mine has had several cats do the live wire dance on his pole transformer for his farm over the years. They come down just like that dummy on the train did! Crispy and flaming! __________________ "The squeaky wheel often squeaks because its the one carrying the heaviest load." -- tcmtech "Make me laugh, think and argue and I will call you my friend" -- tcmtech "If you have to ask for help on an IQ test, you're really not getting the point." -- tcmtech Last edited by tcmtech; 4th July 2009 at 10:16 PM.

4th July 2009, 10:19 PM	#18
smanches	I agree with crutschow. My uncle worked as an electrician at the mines where they run 100KV. When I was a kid I asked him why the birds didn't get electrocuted, he went on to explain they weren't grounded. I do remember asking him if I could hang from the wires, and he explained that because we're so much larger than the birds, the capacitance of our bodies could still be enough to kill us, even not being grounded. And then a college kid proved it to us a number of years later. Stupid fraternity dare. And that was only on the normal street wires, which I think are only 4KV.

4th July 2009, 10:37 PM	#19
tcmtech	One of my college professors had a video of a guy in a bucket truck in some foreign country that took a hit off a 69 Kv main line while trying to hook up an illegal substation for a small village. An uninsulated truck and and apparently a fairly conductive hot stick (broom handle) was used! He basically exploded, the fiberglass bucket bursts into flames, the truck tires explode, the boom operator gets severe burns from the hydraulic system when it blows up and shoots flaming oil all over the truck. The operator did manage to jump free and run away while the whole truck burned up in a matter of a few minutes. By the time the emergency crews get there the whole truck had burned up. They said the bucket guy was half his regular weight when they buried him. __________________ "The squeaky wheel often squeaks because its the one carrying the heaviest load." -- tcmtech "Make me laugh, think and argue and I will call you my friend" -- tcmtech "If you have to ask for help on an IQ test, you're really not getting the point." -- tcmtech

4th July 2009, 11:59 PM	#20
Hero999	I doubt you can be electrocuted by touching a single phase of an HT line, if you're not grounded or connected to a huge metallic object. Assuming 100pF in series with 1k (the standard human body model) and the US power line frequency of 60Hz. We can ignore the 1k for now because it'll be insignifcant compared to the capacitance at 60Hz. $Z = \frac{1}{2\pi FC}= \frac{1}{2\pi \times 60 \times 100\times 10^{-12}}= 26.53 \times 10^6 \Omega$ 26.5M is one hell of a high impedance! For a 100kV line: $I = {100 \times 10^3 }\times {26.53 \times 10^6} = 3.77 \times 10^{-3}A$ 3.8mA might give you a small shock but it certainly won't kill you, more likely than not you'll just swear. What about the power dissipation? Will 3.77mA at 100kV burn you? No, it won't. Why? Because you only need to take the current and resistance into account, the rest is just reactive impedance. $P = I^2 R = (3.77 \times 10^{-3})^2 \times 1000 = 14.21 \times 10^{-3}W$ 14.21mW isn't going to burn you. In the instances you're talking about the electricity was finding a path to earth, one way or another. The fibre glass bucket wouldn't provide good enough insulation, a spark could easily track down the side. The helicopter is a huge metalic object with a much higher capacitance than a human so a lethal current could flow. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

5th July 2009, 04:40 AM	#21
Andy1845c	TCMs story reminds me of this video. Maybe some of you have seen it. Its a testament to the danger of powerlines. YouTube - Crane hits power line __________________ This message transmitted on 100% recycled electrons

5th July 2009, 02:36 PM	#22
Mr RB	I think some of the difference is due to the difference between 110v ac and 240v ac. I've had numerous shocks from both (and even once from 415v ac which HURTS) and 110v barely rates a mention in pain terms. I forget most of you guys only get the chance to be zapped with 110v, you miss all the fun. 240v will give a nasty tingle even when you are insulated, especially if you have extra capacitance elsewhere on your body like a sweaty work shirt etc.

5th July 2009, 03:24 PM	#23
Pommie	My experience was in the UK and 230V phase to neutral - 440 phase to phase. I have had many shocks at 240V as I am sure most (older) UK posters here have. I have never experiences 440V as that requires contacting two phases. I did, unfortunately, have a Friend that did experience contact with two phases and I attended his funeral with his wife and daughter. He was in a lift motor room when an apprentice turned the power back on - I'm guessing that apprentice will never make that mistake again. For anyone curious, this was 11 years ago. Mike.

5th July 2009, 03:30 PM	#24
Hero999	Did the apprentice get manslaughter? __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

5th July 2009, 03:32 PM	#25
whiz115	if you need to close circuit with the earth so you can get electrocuted then why when you accidentaly touch the live in the mains you get a nasty shock?!

5th July 2009, 04:11 PM	#26
KMoffett	You won't...unless some other part of your body/clothes(sweaty) is providing a resistive or large capacitive path to ground. Ken __________________ "To invent, you need a good imagination and a pile of junk." Thomas A. Edison (1847 - 1931)

5th July 2009, 04:55 PM	#30
Hero999	I doubt they were just holding the live wire, probably live and neutral or live and an earth or an earthed object. When you mean electrocuted do you mean killed or just a bad shock? I've seen people being shocked but never electrocuted. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.