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  • #31
    Current is proportional to voltage AND resistance. It's all about voltage plus resistance when it comes to electrocution, especially skin resistance.
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    • #32
      All this talk of electrical shocks, by far the highest number of electrical accidents each year are due to flash-over burns.
      http://www.electricalreview.co.uk/features/5010-11509
      Max.

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      • #33
        Around here for quite a while it was due to idiots trying to steal live electrical wiring in substations and wiring vaults. A number of them turned to charcoal. They are supposedly cracking down on the scrap dealers lately so there haven't been as many.
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        • #34
          I was just about to bring up the difference,

          The thing with massive amps and low volts is this - it's easy to let down your guard because you think your "safe"

          and really you are, until you bring a highly conductive tool into the 12 volt battery bank and ground it out,,, then boom. even though you could touch the "ran in parallel" final leads with your hands and get no shock what-so-ever,,,

          in low voltage high amps your not the critical factor - the highly conductive tool is, and it along with the lead or copper terminals will turn into a molten blast of liquified metal...

          BUT, in high voltage and even far lower amps the tools not the only thing that's conductive - you are,,,
          you watch everything as everything is critical, Evan just said it - it's all about skin resistance - and once it decides to breach that barrier it's home free for conductivity, and the higher the volts the easier that barrier is breached...

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          • #35
            The Canadian volts aren't as big as US volts. That is why they need more of them to get the job done. 120 vs. 600 Those Canadian volts must be real small.


            I got zapped a year ago last January with 380 volts. It is only just now that I am getting back to normal. It caused quite a bit of scarring internally according to my doctor. A lot of heart problems because of the shock. For over one year I had nearly zero energy. Only my cantankerous hard nature let me function at all.
            How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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            • #36
              The factor that is probably most related to the damage done by an electric shock is the amount of energy delivered to the various organs of the body. Power may be a better word here as time is a factor because if a certain amount of energy is delivered over days or weeks it may have no noticable effect while if it is delivered in a short time, like one second or less, then the effects will be much worse.

              The argument over Voltage vs. current is really useless unless all the factors that are involved in the delivery of the energy to the various organs is discussed in detail.

              That being said, I have been bit by 115 VAC and by 40,000 VDC and obviously survived both. The 40 KV went through and through; I had the burn marks on hand and foot to prove it. I can tell you that the 40 KV left me in a shaken state for four or six hours afterward while the 115 V can be shaken off in a few minutes. I was fortunate in that the 40 KV came from a limited current source and it probably shut down after the capacitors discharged (through me).

              If the other factors are unknown, then I am firmly convinced that the higher the Voltage, the more danger you are in from being shocked from it.
              Paul A.

              Make it fit.
              You can't win and there is a penalty for trying!

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              • #37
                http://hypertextbook.com/facts/2000/JackHsu.shtml

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                • #38
                  And still the fact remains, skin is an insulator of sorts, esp. when compared to our more conductive "juicier" centers...

                  that being said Volts are the most critical part of the equation when it comes to current being able to pass through us - if this was not true then me and every single mechanic ever living would be dead just by simple car battery installations - and in fact car batteries are a really good example to use as they have copious amounts of on demand relentless amperage - but their very safe for us to work around bare hands and all and will not electrocute us,,, just don't drop your breaker bar across one... or make two little + and - paddles and place them on each side of your open heart...

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                  • #39
                    575 (600) vac is the reason I have to carry a Lincoln Invertec V-275S welder in the service van, along the Canadian border, paper mills, co-gens and a few other facilities, 575 vac is their standard. I carry the Lincoln (208/230/460460, single or 3 phase) for the 575 vac ability and also a Miller Maxstar 200SD (120/208/230/460, single or 3 phase) for the ability to run 120 vac.
                    jack

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                    • #40
                      Originally posted by Evan View Post
                      It's a legal thing. To work on systems that run higher than 600 volts you need better credentials. With systems 600 volt or lower you can use in house trained and qualified people. To work on higher than 600 you need a fully trained high voltage qualified electrician to even touch anything to do with the system wiring.
                      not in Alberta anything over 240v you need a Sparky, most Commercial and Industrial sites you need a Red Seal Sparky period.

                      600v is the limit of voltage for standard type (R 90 , TWH, ...) WIRE insulations. The higher the voltage the less amps for the same energy, ie a 20 H.P. 208v 3 phase motor will have a FLA of 60 amps or more, a 600v motor will draw 20 amps, letting you use smaller wire, contacters etc.

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                      • #41
                        Yes but whether I grab a pair of 600V wires or a pair of 120V wires my body resistance is the same. So the current is proportional to the voltage.

                        Phil

                        Originally posted by Evan View Post
                        Current is proportional to voltage AND resistance. It's all about voltage plus resistance when it comes to electrocution, especially skin resistance.

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                        • #42
                          not in Alberta anything over 240v you need a Sparky, most Commercial and Industrial sites you need a Red Seal Sparky period.
                          Yes, but you may also have house trained people working under the supervision of a licensed electrician. Same as when I worked on aircraft. I was not a certified AME but as long as there was one supervising my work that was all that was needed.
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                          • #43
                            Yes but whether I grab a pair of 600V wires or a pair of 120V wires my body resistance is the same. So the current is proportional to the voltage.
                            That depends on how much you are sweating about working on the higher voltages....
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                            • #44
                              True, but then that would make higher voltages proportionally evan more dangerous.

                              Phil

                              Originally posted by Evan View Post
                              That depends on how much you are sweating about working on the higher voltages....

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                              • #45
                                Either 600 or 120 will kill. 110 centre tap earthed tends to be a lot more survivable because you're more likely to only see 55V.

                                Over here we're 240/415 (tending towards 220/380 on new installations). I've had belts of 240 and 110 and 110 scares the sh!t out of me, but that's only because several of those shocks were quite bad and all of the 240 ones were minor.

                                At the end of the day, even the ringing voltage and current on a phone line can kill. As the instructions for operators of open switchgear at GEC Machines (ex BTH) said:- "Operators must keep one hand in their pocket at all times when operating switchgear." Think about it.

                                PS. 575-600V doesn't seem to be a nice SQRT(3) factor from a usable lower voltage. Is it stepped down from 1000V, with 220-240V single phase derived completely separately?
                                Location- Rugby, Warwickshire. UK

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