Why wasn't I electrocuted?

cyclonebri1

Rockingit wrote: »

Nope! The fish are effectively completely insulated. Even if there was 10,000V dropped into the tank, so long as the water stays within the glass (which is a superb insulator) there is no circuit to be made. It's what is known as the Faraday Cage principle. Have a look around on you tube for video's of people servicing ultra high tension power lines and radio masts whilst still live and you'll get the idea.

I didn't believe this until I put the probes of a multimeter set to resistance in water. There is no circuit.

vaio

Rockingit wrote: »

Nope! The fish are effectively completely insulated. Even if there was 10,000V dropped into the tank, so long as the water stays within the glass (which is a superb insulator) there is no circuit to be made. It's what is known as the Faraday Cage principle. Have a look around on you tube for video's of people servicing ultra high tension power lines and radio masts whilst still live and you'll get the idea.

Nah, Faraday cages only work on radiated fields not direct contact.

The reason the fish (and power line workers) survive is because there is no current flow/voltage gradient across the fish/worker.

Air is a good insulator so a power worker with one hand on a 10 kV line is safe as long as no part of him is in contact with anything at a different potential. No potential difference = no current flow.

Dirty water is a good(ish) conductor so a every part of a fish in a 10 kV tank is in contact with water at the same potential so again, no potential difference = no current flow

Myser

vaio wrote: »

Nah, Faraday cages only work on radiated fields not direct contact.

The reason the fish (and power line workers) survive is because there is no current flow/voltage gradient across the fish/worker.

Air is a good insulator so a power worker with one hand on a 10 kV line is safe as long as no part of him is in contact with anything at a different potential. No potential difference = no current flow.

Dirty water is a good(ish) conductor so a every part of a fish in a 10 kV tank is in contact with water at the same potential so again, no potential difference = no current flow

The same also goes for birds perched on live High Voltage lines - since both of their feet are at the same potential.

Note, there is a difference between receiving an electric shock and being electrocuted. Electrocuted is short for Electro Executed i.e. you die as a result of contact with electricity. If you receive an electric shock, you may be injured or feel some pain.

vaio

Myser wrote: »

........Note, there is a difference between receiving an electric shock and being electrocuted. Electrocuted is short for Electro Executed i.e. you die as a result of contact with electricity. If you receive an electric shock, you may be injured or feel some pain.

Interesting, I'd have thought that "Electro Executed" implied a deliberate act so the US legal system could electrocute you but I could accidentally die from an electric shock.

I guess common usage has removed the difference

Myser

vaio wrote: »

Interesting, I'd have thought that "Electro Executed" implied a deliberate act so the US legal system could electrocute you but I could accidentally die from an electric shock.

I guess common usage has removed the difference

If you die as a result of contact with electricity, that would be electrocution.

There are two contexts for electrocution: One as in the US death penalty where you die by electric chair. The other, where you are killed as a result of malicious/self-inflicted or accidental contact with electricity. Malicious could be someone purposely leaving some equipment live or unsafe so that the intended victim is killed as a result. Self-inflicted to commit suicide by placing an electric appliance into a bath full of water whilst inside.

Here is a page on First Aid advice from the ESC on how to assist someone experiencing an electric shock:

http://www.esc.org.uk/public/guides-and-advice/first-aid/

Note that it doesn't mention dying anywhere.

sillygoose

vaio wrote: »

Nah, Faraday cages only work on radiated fields not direct contact.

The reason the fish (and power line workers) survive is because there is no current flow/voltage gradient across the fish/worker.

Air is a good insulator so a power worker with one hand on a 10 kV line is safe as long as no part of him is in contact with anything at a different potential. No potential difference = no current flow.

Dirty water is a good(ish) conductor so a every part of a fish in a 10 kV tank is in contact with water at the same potential so again, no potential difference = no current flow

:cool: the first accurate post on the thread. :T:T:T

vaio

Myser wrote: »

If you die as a result of contact with electricity, that would be electrocution.

There are two contexts for electrocution: One as in the US death penalty where you die by electric chair. The other, where you are killed as a result of malicious/self-inflicted or accidental contact with electricity. Malicious could be someone purposely leaving some equipment live or unsafe so that the intended victim is killed as a result. Self-inflicted to commit suicide by placing an electric appliance into a bath full of water whilst inside.

Here is a page on First Aid advice from the ESC on how to assist someone experiencing an electric shock:

http://www.esc.org.uk/public/guides-and-advice/first-aid/

Note that it doesn't mention dying anywhere.

Yep, common usage has removed the need for the deliberate act of execution.

That ESC page is a bit crap & bland particularly ".......After removing the person from the source of electricity, if the person is unconscious call for an ambulance immediately. Only those with the necessary knowledge and skill should carry out first aid......."

The notices we use say something along the lines of " if the person is unconscious call for an ambulance and then check for pulse & breathing and and do mouth to mouth or CPR as appropriate"

It then goes on to give instruction on how to do mouth to mouth & CPR.

Obviously in an ideal world with me unconscious and with no pulse I'd rather the person doing CPR was fully skilled & trained but given I'll be brain dead in the 10 mins it's going to take the ambulance & defib unit to turn up, I'll settle for someone whose training consists of having seen the vinny jones advert having a go.

vaio

cyclonebri1 wrote: »

I didn't believe this until I put the probes of a multimeter set to resistance in water. There is no circuit.

Pure water is a good insulator, dirty water (inc tap water) is a better conductor than the human body which is why a shock is worse if the person involved is wet.

I once went to a land drainage pumping station....(underground room with incoming mains supply & a pump control panel used to regulate the water table level.)

When we opened the access trap door the room was flooded and the water around the submerged incoming meter head was actually boiling & producing steam.

cyclonebri1

Myser wrote: »

The same also goes for birds perched on live High Voltage lines - since both of their feet are at the same potential.

Note, there is a difference between receiving an electric shock and being electrocuted. Electrocuted is short for Electro Executed i.e. you die as a result of contact with electricity. If you receive an electric shock, you may be injured or feel some pain.

It was strange in India to see roasted fruit bats on the overhead lines.
They root by hanging from 1, unfortunately they are just longer than the space between the lines, and if a breeze gets up it's :eek::eek::eek::eek:

One day the darwin effect will kick in and they will hang from the bottom line only;);)

As an angler great measures are taken to prevent eelctrocution, , from overhead power lines. All lines crossing or near rivers and lakes are signed to the effect of instant death.
Rods and poles are now almost all carbon fibre and that's a great conductor of electricity. Given that some lines are down to 8mtr or less in places, and that a pole can be 15mtr long it is a real issue, there have been deaths.:(:(

System

At one point 1st Aid instructions were to call help and not attempt CPR for heart stopped incidents. ISTR that lasted about 2 years before they changed it