If you're only touching one conductor there's no route back to the other side of the supply. Disclaimer - this is theory, I haven't tried it. Mike Popham and Lee on Solent. By Keef - Sat Jun 09, Just got in, boss. Been in Norfolk, now back in Ethics. Your body's inherent resistance doesn't know what the voltage is.
So if you stick your hand across v, X milliamps will flow. It's very risky, unless you're like me, with unusually dry skin and hence very high skin resistance. Then you swear very loudly.
I've probably done it four or five times in my lifetime and have now given up the idea. Personally, if I were in a situation where I might grab hold of the electric supply, I'd rather it were something like 24 volts. Even can be a nasty surprise if you grab one pole with each hand. I've had hold of something that was at something like , volts - but there was no power available, and virtually zero milliamps.
It was amusing to see the inch-long spark leap to my finger, and it tickled a bit. Do that with the overhead national grid at the same voltage, and you'll be smoke. By bibendum - Sat Jun 09, To make the maths easy, assume that the resistance of the 'human' is ohms. At V this gives a current of 2. Does that help? By BlueRobin - Sat Jun 09, BlueRobin wrote: My shed is full of v power tools, apparently it is to do with site safety.
My shed is full of volt power tools. It's to do with living in England rather than the USA. You get far better performance at the end of a long line with volts rather than volts, because you need less than half the current to provide the same power.
Topic Tools. View similar topics Print this topic. Some time ago I was working on building site with some German engineers who were using V double insulated tools with RCD protection. The UK engineers were using V hand tools. The practice of using V hand tools with RCDs is common in continental Europe and to ensure that those workers were not disadvantaged by having to buy or rent V hand tools when they work in the UK, this directive was brought in.
But I can't find any paper work on this. Does anyone else know about this or is it in my imagination? Top : Bottom. GeoffBlackwell Posts: Joined: 18 January Well I don't think that is the subject of a specific EU Directive but it is effectively true. BTW I do not know of any 'rule' which says that only class II equipment can be used - it would be very difficult to prevent the use of class 1 equipment.
People I have spoken to in the HSE do not favour this approach but they cannot prevent it. If we compare the fault protection indirect contact provided by this system with that provided by the Reduced Low Voltage System RLVS v - commonly used in the UK - we could highlight two problems: 1 Assuming some equipment is class 1 - what happens if the RCD fails - Note that failure of the RCD for class II equipment does not present a fault protection indirect contact hazard.
Damage to cables could occur these may not be armoured and this may create a hazard. Note that in the UK a construction site may have a TN-S supply high fault levels , whereas in continental Europe it would probably have a TT supply low fault levels. Regards Geoff Blackwell. Hi all BS Thanks Geoff and theroc for your input.
I remember at the time the Germans had long arguments with the site foreman before they were allowed to start work. It seems to vary from site to site. I do work for MOD N and I have all the relevant specifications and operating guides but if I do not go and talk to the electrical superintendent for the particular project I am working on, I am asking for trouble!
The superintendent will want the work done "his way" whatever the regulations state! I worked on a new Hospital where there were arguements because some guys had been caught with a v lead out of the canteen window into the work area, as the arguement went on the screeders were laughing, when I enquired why they said they had a v three phase screed pan mixer on the way to the site and they guessed that would really!
Andy Betteridge. I have the HSE Electrical safety on Construction Site Book in front of me, some quotes: page paragraph Due to the delicate nature of a RCD, it is not ideal for use in the rough enviroment of a construction site etc page paragraph An RCD does not gaurantee safety. They will only protect against earth faults, and will not operate when there is no connection to earth, ie if current is passing from live to neutral. So it is possible to suffer electric shock and injury even though the RCD is operating correctly.
Paragraph It is therefore not possible to place total or near total reliance for personal safety on RCDs. In contrast the use of passive systems, such as reduced low voltage, can give reliable protection against fatal electric shock. Paragraph The installation of a RCD wiull not make a system safe if it has been poorly designed or installed etc.
Edited: 17 June at pm by sparkingchip. If you were doing the risk assesment for v tools versus v, you would have to remove any of the potential dangers that you possibly could. Full stop. Risk of electric shock from v, hardly never, likely outcome - nothing. No brainer really. Big stuff is on , but again not on a lead. The outcome is easily solved on most sites: Canary wharf, white city, wembley, anywhere really.
You get a red card and you leave site never to come back P Lack of planning on your part doesn't make it an emergency on mine What is V? Do you Need V? Like this story? Please Share! Like our site?
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