I understand it's the 'Electricity at Work regulations' in the context of preventing access to live conductors by unskilled personnel which is usually alleged to be the reason for the so called ban, so it's a part of Health and Safety associated legislation.
...
Regulation 7 of the
The Electricity at Work Regulations 1989 states...
Insulation, protection and placing of conductors
7. All conductors in a system which may give rise to danger shall either
(a)be suitably covered with insulating material and as necessary protected so as to prevent, so far as is reasonably practicable, danger; or
(b)have such precautions taken in respect of them (including, where appropriate, their being suitably placed) as will prevent, so far as is reasonably practicable, danger.
In the railway context, the DC 3rd rail and AC 25kV OHLE contact wire are live conductors but are not covered with insulating material. The key phrase here is "suitably placed". In the generic case, danger is prevented by putting the conductor out of reach, which in practice means high up and/or protected by barriers (secure fencing?).
As has been stated elsewhere, there is no specific legislation as far as I am aware to prevent 3rd rail systems.
As well as the Health and Safety at Work Act 1974 and various H&S regulations (mentioned elsewhere in the context of electrical safety) there is also the IEEE Wiring Regulations (BS7671) which relate to design. If (heaven forbid) there was to be a fatal accident then the Corporate Manslaughter and Corporate Homicide Act 2007 may also be relevant.
I was under the impression that urine as a constant flow replicates rainfall by being in droplet form and does not conduct electricity.
Well put it this way, I wouldn't want to pee on the 3rd rail given that urine will conduct electricity better than water/rainwater.
You could walk barefoot on a juice rail (have seen it done) as long as you don't earth it.
You could; for the same reason as birds can perch on power lines (even ones which carry 400kV) and don't get fried. In effect what you have is an equipotential zone or Faraday cage. No potential difference; no current = safe.
urine forms droplets like rain .... DC needs a continuous circuit in order to flow .... it can't jump like AC does .... so urination onto DC 3rd rail won't cause electric shock ....
I beg to differ. Electricity can jump/arc (whether it is DC or AC). How far depends on the potential difference, and how big the gap is. Your petrol driven car requires a spark which comes from a DC battery for example.
No they wont, the human body has enough resistance to prevent enough current flowing (and it needs to be several 1000 amps worth) to trip the circuit breakers and the current will continue to flow.
Fact is it doesn't take much current to kill - as little as 50 - 80mA (milliamps) (0.05 - 0.08A) can have fatal consequences. Death is likely to occur as a result of ventricular fibrillation and severe internal and external burns. All new domestic electrical installations (230V) incorporate some form of RCD protection. The RCD will shut off the power and is normally triggered with a fault current of 30mA.
Normal steel toe capped safety shoes and the voltage on the underground is a nominal 660v DC made up of (on the underground sections) +440v in the 3rd rail and -220v in the 4th rail), Network rail is a nominal 750v DC.
but the underground carries a much lower current than NR, remember its the volts that jolts, the current that kills.
Higher voltage (potential) means a lower current is required for the same power output [Power = Volts x Amps]. Electricity can be distributed much more efficiently using AC. The voltage can be changed much more easily too using transformers. Higher transmission voltages (up to 400kV) means the current is less and transmission losses (voltage drop) is reduced / efficiency increased.
If anywhere new is to be electrified then it will be 25kv overhead because DC 3rd rail is very inefficient and so expensive to run compared to overhead AC, 3rd rail normally has to have a feeder station every 3 miles or so where-as 25kv its a lot lot further (sorry I cant remember off hand) and DC loses a lot of energy. So while the installation of the bits on the track are cheaper for 3rd rail by the time you factor in the substations and running cost etc then 25kv (as long as its designed and built to a decent standard) is much much cheaper in the long run.
I personally doubt if we will see any further 3rd rail installations, certainly not large scale. Depending on the outcome of Basingstoke-Southampton Port conversion to OHLE we may well see other conversions in the not too distant future. Channel Tunnel-Ashford-Tonbridge-Redhill-Guildford-Reading anyone?