Amps carried through air

[Simon G]

Hi everyone,
Watched a programme recently on TV, a young man was on top of a train (not advised) and the power lines above him carried 10,000 volts. He got too close and it jumped through the air and got him. Thankfully he lived and made a decent recovery.
My question being, is it even possible to take an educated guess at how many amps went through him? Say he was 2-3” away from the wire, with air being a poor conductor, I would of thought 1A would of still been enough to take his life no problem.
From what I’ve read about online this is no easy question, say weather circumstances where not raining.
Looking forward to responses!

 

[Strima]

Anyones guess. Without knowing how conductive he was, how good the path to earth, humidity, his water content, what shoes he was wearing, this list goes on.

 

[Silly Sausage]

Good question!
I would've thought that the actual arc would have very little resistance due to it being plasma, so the current would be limited by the person/train combo to Earth.

 

[freddo]

An arc being plasma is very low resistance, bypass the series resistance on an arc light and the supply fuse will blow.

 

[Rpa07]

His flip flops had probably fallen off giving him a clean contact of sweaty foot to aluminium carriage roof - IDIOT!

 

[jackhammerJIM]

In dry conditions the human body alone can have a resistance of 100 000 ohms . However , during a sustained shock this resistance will drop rapidly .

Ignoring the air
10 000/100000 = 0.1 amperes

 

[Squid]

My ex BIL worked/works at a energy production plant in Gdansk and years ago a maintenance guy entered a generator for maintenance, to be honest I can't remember the full story but the power surge cooked his body from the inside and he died in pain a few days later.

 

[Rpa07]

Well thats that bowl of Weetabix ruined, Cheers SWD!

My ex BIL worked/works at a energy production plant in Gdansk and years ago a maintenance guy entered a generator for maintenance, to be honest I can't remember the full story but the power surge cooked his body from the inside and he died in pain a few days later.

 

[Simon G]

In dry conditions the human body alone can have a resistance of 100 000 ohms . However , during a sustained shock this resistance will drop rapidly .

Ignoring the air
10 000/100000 = 0.1 amperes

And I suppose with it jumping through the air it could well have not been sustained for long at all, so with the air space included it could likely be less than 0.1amps? That makes sense how he may have miraculously survived it

 

[SparkyChick]

The human body is actually quite a good conductor once you get below the skin, we are made up largely of water and a chemical soup that includes salts of various forms.

Under the right conditions you could be looking at 500 ohms. So for 10kV that would be 20A, and 20A is more than capable of heating things up rather quickly.

So factoring in the plasma, he was probably the current limiter.

 

[static zap]

Going to have burns like putting your hand/foot
quickly in a pan of boiling water .
Burnt bones and bad nerve damage ?
Photos of contact burns may be interesting !
(if not eating burnt toast) ,
Twigletts have been getting evermore
carbon coated of late !
--Wondering if ejected steam keeps plasma a little less close , Expansion of water->-steam is amazing .

 

[dmxtothemax]

The most likely reason he survived was because of the path that the current took, in this case I sur mise that the bulk of the current traveled thru his extremity (skin), this makes sense when you think about it, cause it is where the most water is. very little if any traveled thru vital area's such as the heart or brain, couple this with the fact that it was only brief means he should buy a casket ticket, cause good luck was his this day.

 

[johnduffell]

Wondering if ejected steam keeps plasma a little less close , Expansion of water->-steam is amazing .

Yes it is Leidenfrost effect - Wikipedia - https://en.m.wikipedia.org/wiki/Leidenfrost_effect

 

[oracle]

Once fitted wireless switches and the lady of the house asked me to fit wireless sockets.
That would really be amps carried through the air, and she wanted a detailed explanation why she couldn't have them.
I said that the electrical mifragulator would become condified making the whole room driviled. She just said "Oh" and left it .

 

[Squid]

Once fitted wireless switches and the lady of the house asked me to fit wireless sockets.
That would really be amps carried through the air, and she wanted a detailed explanation why she couldn't have them.
I said that the electrical mifragulator would become condified making the whole room driviled. She just said "Oh" and left it .

You should have billed her for the shoe box of "free amps" that you left behind.

 

[plugsandsparks]

Surely, you could have said , "No one makes them" - you could have double checked with your wholesaler and handed the phone to her, so she could ask them direct....... would have been a cracker..

 

[Deleted member 105166]

Watched a programme recently on TV, a young man was on top of a train (not advised) and the power lines above him carried 10,000 volts.

For info - if in the UK, the OLE is 25kV, not 10kV

 

[45140]

The majority of the European railway network operates on 25kV. There are some notable exceptions but going into that will only muddy the water.

I have summarised to the main principles greatly so please do not pick faults as it is a complicated subject and I KNOW that some things are omitted but I have done this to make it easily readable.

Under the EU technical standards for interoperability (TSI) trains draw about 200 amps when accelerating, and the protection settings are set at 600 amps full maintained feeding within each principal section of the route.

The OHL operates at between 23.5kV and 29.5kV in normal service and the trains are designed to operate normally within that envelope.

The system is designed to withstand fault currents of up 12kA, and BR short circuit testing work some years ago identified voltage running up to 60kV before the breakers tripped.

Currently the system is based upon a nominal maximum of 60v running from the train into the track. This is the maximum voltage permitted in these circumstances on an electrified railway.

The protection settings are set for the breakers to trip at a maximum of 12kA , with a disconnect time of 3m/s (0.03 second). Traction return and equipotential earth bonding ensures that in most circumstances the railway infrastructure becomes a large Faraday cage, however the SCADA system is design for the protection of the trains and Equipment. Whilst in normal operational condition s a member of the public would not become exposed to the risk of electrical shock, that is only the case for someone acting in an appropriately responsible way. The system is NOT designed for intentional touching (or urination onto the Equipment - which does happen) and in such cases (IF you are lucky) you will die, if you are unlucky you will suffer very severe burns to the body surface, your clothes will be on fire, and the only treatment is to be anaesthetized and placed into a bath of oil whilst you die slowly and painfully or possibly recover to horrendous injuries.

It is interesting to note that I calculated a short circuit in a domestic premises could easily generate over 900 amps and I believe the rated Ampage protecting the DNO equipment is is something like 16kA.

Hope this helps ?

 

[45140]

With regards to the arcing distance to an earthed object from railway OHL Equipment, various academic studies have suggested that the dielectric in air as 21 degrees C and normal humidity is between about 3mm per 1kV.

Tests I have undertaken have demonstrated that 1mm/1kV is to be expected in air with water vapour, and obviously the tendency to arc will also be related to the shape of the component carrying the current.

 

[w0z]

The majority of the European railway network operates on 25kV. There are some notable exceptions but going into that will only muddy the water.

I have summarised to the main principles greatly so please do not pick faults as it is a complicated subject and I KNOW that some things are omitted but I have done this to make it easily readable.

Under the EU technical standards for interoperability (TSI) trains draw about 200 amps when accelerating, and the protection settings are set at 600 amps full maintained feeding within each principal section of the route.

The OHL operates at between 23.5kV and 29.5kV in normal service and the trains are designed to operate normally within that envelope.

The system is designed to withstand fault currents of up 12kA, and BR short circuit testing work some years ago identified voltage running up to 60kV before the breakers tripped.

Currently the system is based upon a nominal maximum of 60v running from the train into the track. This is the maximum voltage permitted in these circumstances on an electrified railway.

The protection settings are set for the breakers to trip at a maximum of 12kA , with a disconnect time of 3m/s (0.03 second). Traction return and equipotential earth bonding ensures that in most circumstances the railway infrastructure becomes a large Faraday cage, however the SCADA system is design for the protection of the trains and Equipment. Whilst in normal operational condition s a member of the public would not become exposed to the risk of electrical shock, that is only the case for someone acting in an appropriately responsible way. The system is NOT designed for intentional touching (or urination onto the Equipment - which does happen) and in such cases (IF you are lucky) you will die, if you are unlucky you will suffer very severe burns to the body surface, your clothes will be on fire, and the only treatment is to be anaesthetized and placed into a bath of oil whilst you die slowly and painfully or possibly recover to horrendous injuries.

It is interesting to note that I calculated a short circuit in a domestic premises could easily generate over 900 amps and I believe the rated Ampage protecting the DNO equipment is is something like 16kA.

Hope this helps ?

I have an essentially unrelated question, save for the fact that it's train related. Intercity trains have 13A sockets for use of passengers. How is the voltage and waveform regulated for these? I ask because someone I know recently had a laptop supply and it got VERY hot compared to how it usually runs at home. If I had a portable scope I'd be tempted to take it with me next time I'm on a train...