Rcd tripping

[Kev2632]

Should the rcd trip everytime if somebody had softly touched the live core of a cable? Or does it depend on wha current is flowing?

 

[tony mc]

Hi KEV

The RCD may not have tripped for many reasons and it is impossible to guess writing on the forum.

If you have any concerns you should have the RCD checked out by someone with the necessary test equipment and competance to do so to put your mind at ease.

I would also mention that touching any live conductor is frought with danger even if it is RCD protected as they are mechanical and can fail !

 

[Kev2632]

Hi KEV

The RCD may not have tripped for many reasons and it is impossible to guess writing on the forum.

If you have any concerns you should have the RCD checked out by someone with the necessary test equipment and competance to do so to put your mind at ease.

I would also mention that touching any live conductor is frought with danger even if it is RCD protected as they are mechanical and can fail !

Yea I understand what your saying, but in reality it should have tripped because the person was earthed standing on e concrete floor yea?

 

[Paul.M]

No Kev, your mate was isolated from a return path to earth because he was standing on a none conductive material (and hopefully wearing shoes).

If he touched something that was earthed i.e. a backbox he would be part of circuit, live to earth. Therefore receiving a shock up to the value of the protective device (30mA in this case) until it tripped.

If no contact to earth is made you are just a part of the line conductor and electricity will flow through you, that's why crows etc can sit/stand on HV overhead lines without being killed but don't try any home experiments, could be fatal.

This is what I believe happened to your friend, he became part of the conductor and did not complete a circuit by touching earth or neutral.

 

[Kev2632]

That's it lad thanks very much

 

[telectrix]

that's why crows etc can sit/stand on HV overhead lines without being killed

can still shoot the buggers though.

 

[Kev2632]

that's why crows etc can sit/stand on HV overhead lines without being killed

can still shoot the buggers though.

doesnt the birdies feel a shock like us humans then?

 

[wolvesmad1]

need help

 

[GaryM]

need help

You need help? In what way?

 

[brooky25]

doesnt the birdies feel a shock like us humans then?

Birds are not in contact with terra firma so no path to earth. You can sit there with them if you fancy it

 

[Kev2632]

Birds are not in contact with terra firma so no path to earth. You can sit there with them if you fancy it

haha yea nooo bother well why was it then that when the person touched the live conductor whilst standing on a concrete floor he received a shock? as the concrete isnt a conductor...is this not the same as the sitting on a live wire then?

 

[brooky25]

If your feet are not touching terra firma (ground) there is no path to earth.

You still create the shortest path to earth if you are stood on the ground, be it concrete or whatever.

Have you never seen anyone checking overhead lines ? Dropped out of a helicopter ie not touching ground so no earth path

 

[Kev2632]

If your feet are not touching terra firma (ground) there is no path to earth.

You still create the shortest path to earth if you are stood on the ground, be it concrete or whatever.

So even if the current cant get to earth it will still flow through the person is at correct, even thought your standing on concrete is at correct??? but stop at the concrete because its not a conductor and cant get too earth ?

 

[wolvesmad1]

how do i start a new thread?

 

[GaryM]

how do i start a new thread?

Come out of this thread, into the forum, choose a sub forum then click 'post new thread'

http://www.electriciansforums.net/

 

[brooky25]

Watch this
Lineman at work - YouTube

or this
Helicopter Transfering Lineman to Wire - YouTube

or this

http://www.youtube.com/watch?v=6MXMJ_7mGxQ&feature=related