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John Henry · 12-22-2003, 03:15 PM

Here in the UK, we have 230V. While I would not recommend plugging yourself in, I have received a number of zaps from the mains and survived with no more (noticeable) damage than a slightly tingly arm.

It's a while since I studied this and I don't remember the equations, so don't take this as gospel, but...

What kills you is not 'amps' or 'volts' or 'hertz', but something called 'skin depth'. This is a measure of how far one 'wave' from the mains can penetrate into you, because if the current is only going into you, not through, it will stop after one wave and 'flail' inside you like an untethered bit of string. Basically if it gets to your heart, you're fucked, but how far it gets depends on current, voltage, frequency and your resistance.

I know that some of the places we fix for have modified power supplies that go from -115V to +115V, whereas the mains goes from 0 to 230V. It may be that this is what you have in the States. Do you have two fuses in your plugs or one?

As I see it, the 0 to 230V system has the disadvantage that if you do get zapped by the mains, you have all its energy being delivered to you, not just half of it. With the -110V to 110V I suppose the disadvantage is that if the fuse on one side blows, the other side has one less place to short out to if it fucks up, making it more likely to zap you. Having said that, if that happened, I suppose the extra current the appliance would try to draw would just blow the other fuse as well. Beats me. As I say, this is all off the top of my head, so don't go testing it in any dangerous ways, but I hope it helps.

12-22-2003, 03:15 PM	#6 (permalink)
John Henry Addict Location: Grey Britain	Here in the UK, we have 230V. While I would not recommend plugging yourself in, I have received a number of zaps from the mains and survived with no more (noticeable) damage than a slightly tingly arm. It's a while since I studied this and I don't remember the equations, so don't take this as gospel, but... What kills you is not 'amps' or 'volts' or 'hertz', but something called 'skin depth'. This is a measure of how far one 'wave' from the mains can penetrate into you, because if the current is only going into you, not through, it will stop after one wave and 'flail' inside you like an untethered bit of string. Basically if it gets to your heart, you're fucked, but how far it gets depends on current, voltage, frequency and your resistance. I know that some of the places we fix for have modified power supplies that go from -115V to +115V, whereas the mains goes from 0 to 230V. It may be that this is what you have in the States. Do you have two fuses in your plugs or one? As I see it, the 0 to 230V system has the disadvantage that if you do get zapped by the mains, you have all its energy being delivered to you, not just half of it. With the -110V to 110V I suppose the disadvantage is that if the fuse on one side blows, the other side has one less place to short out to if it fucks up, making it more likely to zap you. Having said that, if that happened, I suppose the extra current the appliance would try to draw would just blow the other fuse as well. Beats me. As I say, this is all off the top of my head, so don't go testing it in any dangerous ways, but I hope it helps. __________________ "No one was behaving from very Buddhist motives. Then, thought Pigsy, he was hardly a Buddha, nor was he a monkey. Presently, he was a pig spirit changed into a little girl pretending to be a little boy to be offered to a water monster. It was all very simple to a pig spirit."