Apologies, it wasn't intended to be sarcastic, though reading back now, I can see it appears so..
No worries
I realise now that putting 'much more dangerous' was a mistake, I know that both will kill you, but from where I am getting a direct shock from 3rd rail appears much more dangerous partially because of being on the ground and therefore more easily accessible..
What you are referring to here is the increased likelihood from exposure
to, rather than the inherent risk
from the live equipment. This is a pretty common fallacy amongst most people. The point is that a missing earth bond at an OHL Structure can result in a suffficient build up of electricity as to cause a serious electric shock. Similarly a broken yellow rail to rail bond although not normally carrying sufficient current to be dangerous to life can again give rise to a very serious shock or indeed if the right (or wrong) circumstances come together can lead to a fatal electric shock. Red rail to OHL RC conductor wires are treated as live and dangerous to life at all times as they carry high voltages from the running rail. All of these examples are present at ground level and indeed less obvious than the live Conductor rail.
From what I've been taught about DC and AC, I would've said that if you were to survive a major shock from either, the chances would be better for OHL, though still slim..
Whoever taught you that was at best very foolish to let you leave with that perception and at worst an incompetent trainer. If you know him/her please feel free to pass that comment on.
Again people, including Railway trainers who really should know better perpetuate myths that are quite wrong, and Network Rail is particularly bad in this respect because they do not recognise the need to give their safety trainers even a basic understanding of the OHL Equipment, and so the myths continue.
During contact with the OHL, the short circuit generated is sufficently powerful enough to vapourise the water droplets in the air, and the superheated dry air then becomes a superconductor. This is the "flash" one would see. The "bang" one would hear is the rapid explosive expansion of the water droplets, and explains why people are "thrown away" from the OHL Equipment. Quite simply in many cases it is this expansive air force that pushes them away as in any explosion. The myth is that the elctricity "throws" you away because it is alternating. This is quite wrong, and in any case the sine wave cycles are far too frequent to have any effect.
The flash causes sever burns to the skin and causes clothing to go on fire. During the time that a person is in contact with, or is within arcing distance of, the OHL Equipment, the current will be building steadily and rapidly. HV current acts differently on the body in that it will enter the body by the creation of an entry hole, and will then follow the bone structure until it finds a suitable earth at which point it will exit the body. Because the body has a resistance, the current is still building up during this process causing the blood to boil and sometimes vapourise. This of itself causes the internal organs to be cooked. Muscle forms a perfect route for the electricity to follow and thus will be destroyed.
Generally by this time the person is normally dead. In the event that they manage to survive until the breakers trip out, their flesh, nervous system and body are pretty much shot to pieces. They will also be subject to pneumonia as a result of the rapid heating and cooling of the body, as well as the flesh being unable to recover and dying off, with the consequent result of gangrene.
A DC electric shock is very different in that the flash will be much less unless a metallic or other conductive material is involved. A person can fall over the Conductor rail and survive for some time whilst the current continues to flow through their body. It is suggested that the breathing function shuts down so one slowly dies from asphyxiation, whilst the flesh and internal organs are burning and cooking. Some people have been known to burn through without the breakers ever tripping out.
Contact with the Conductor rail is not guarnteed to be always fatal as it depends upon each person's natural resistance (size, weight, build, fat, etc) as well as environmental factors such as what the person is standing on, the type of clothing shoes, etc. It was quite common in BR days for people to get an electric shock through their rain mac as it trailed across the Conductor rail and many SR men have experienced "the hard smack to the back of the neck" which was a certain sign that their coat had touched the third rail..
......Not exactly no, but I know that it is lower than it will be in 3rd rail.
Again you have been misinformed. Fault currents in the OHL Equipment can reach 6000 amps. Fault currents in the Conductor rail system are generally tripped at about 900 amps
