OHLE Question

[ABB125]

If someone hung off the 25kv contact wire, would they be a bit like a pigeon on a power line (not electrocuted), or would they get fried? If they were also touching the ground, would that make any difference?

Note: I'm not trying to commit suicide

 

[Tio Terry]

If someone hung off the 25kv contact wire, would they be a bit like a pigeon on a power line (not electrocuted), or would they get fried? If they were also touching the ground, would that make any difference?

Note: I'm not trying to commit suicide

To get electrocuted you would need a path from the contact wire through you to a return path, such as earth. I'm not quite sure how you think you can get in contact with the 25KV live parts of a railway system without being in contact with a return path in the first place, it's not as if you have wings, like a bird, so can have an air gap in the first place.

 

[GRALISTAIR]

If someone hung off the 25kv contact wire, would they be a bit like a pigeon on a power line (not electrocuted), or would they get fried? If they were also touching the ground, would that make any difference?
Note: I'm not trying to commit suicide

Absolutely it would make a difference - you have now completed a return current path to earth which is theoretically zero potential.

To get electrocuted you would need a path from the contact wire through you to a return path, such as earth. I'm not quite sure how you think you can get in contact with the 25KV live parts of a railway system without being in contact with a return path in the first place, it's not as if you have wings, like a bird, so can have an air gap in the first place.

Yes you would have to jump off a bridge or similar -grab a contact wire and hold on to have no return. I think the system could take to sudden impact of your mass adding to the tension on the wire.

 

[furnessvale]

Absolutely it would make a difference - you have now completed a return current path to earth which is theoretically zero potential.



Yes you would have to jump off a bridge or similar -grab a contact wire and hold on to have no return. I think the system could take to sudden impact of your mass adding to the tension on the wire.

But don't touch the bridge with your head.....as many a pigeon could testify!

 

[GRALISTAIR]

But don't touch the bridge with your head.....as many a pigeon could testify!

exactly -easy return current path

 

[edwin_m]

You wouldn't have to be touching the ground, just get close enough and the voltage will arc across. The actual arcing distance is a lot less than the safety distances quoted in various rules and standards but it's significantly greater than zero.

 

[apk55]

If you climbed up an insulated ladder onto the overhead you would be OK
On the grid system there is live working on 400KV lines, people wear Chain mail suits because of the high electric field.

 

[dgl]

The thing to remember is that in order for you to get an electric shock there either needs to be a connection to ground or a potential difference between a live conductor and another live conductor.

i.e. if you were touching 2 live conductors which were at exactly the same voltage and the phases were locked together then you would not get a shock, however, if the voltage is different (either from a lower voltage conductor or from a conductor at the same voltage but at a different phase) and you will get a shock (well only if the potential difference is great enough).

When people are working on high voltage cabling as well as the protective clothing everything they use that is a conductor (i.e.the basket they are standing in) will be connected to the line they are working on and so will be at the same potential, thus meaning that the potential between the workers and the HV line is essentially 0V.

 

[AndyNLondon]

But don't touch the bridge with your head.....as many a pigeon could testify!

I'd imagine that the pigeons in question are a bit too fried to testify about anything! (Not to mention, a bit too avian...)