3 Phase Electric

[elkangorito]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

[Crossy]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

I think Jenkins is a Brit. and is therefore referring to the 110V site tools that run through an isolating transformer. Neither pole of the 110v is grounded therefore the possibility of shock is reduced even if the tool's metalwork is not earthed.

That said, having the ground as well can't hurt particularly when you drill through a live cable

[elkangorito]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

I think Jenkins is a Brit. and is therefore referring to the 110V site tools that run through an isolating transformer. Neither pole of the 110v is grounded therefore the possibility of shock is reduced even if the tool's metalwork is not earthed.

That said, having the ground as well can't hurt particularly when you drill through a live cable

Thanks Crossy. That makes sense now.

[Naam]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

because "jib approved" electricians tell us so

[Crossy]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

because "jib approved" electricians tell us so

Actually to get JIB approval needs a whole bunch of things, see here:- http://www.jib.org.uk/gdappelec.htm

In reality it means that you can correctly wire a BS1363 plug top

[Crossy]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

I think Jenkins is a Brit. and is therefore referring to the 110V site tools that run through an isolating transformer. Neither pole of the 110v is grounded therefore the possibility of shock is reduced even if the tool's metalwork is not earthed.

That said, having the ground as well can't hurt particularly when you drill through a live cable

Thanks Crossy. That makes sense now.

IMPORTANT CORRECTION I believe my supposition that the 110V is completely earth-free is incorrect. It seems that the site transformers are actually 55-0-55 about earth. 55V is deemed a non-hazardous voltage

[chownah]

IN the US the 110V hot line is 110V relative to ground.

[Naam]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

because "jib approved" electricians tell us so

Actually to get JIB approval needs a whole bunch of things, see here:- http://www.jib.org.uk/gdappelec.htm

In reality it means that you can correctly wire a BS1363 plug top

earthed or unearthed?

[jenkins]

hi chownah newbie here (jib approved electrician )

in the states the supply is 110volts ? in thaland its 220-- a whole different ball game

110 doesn,t nessesarily need earthing ,220 does

also someone stated that a 12 v car battery could electrocute a person , this is totally untrue, any voltage below 55volts is safe

Why doesn't 110 necessarily need earthing...& 220 does?

I think Jenkins is a Brit. and is therefore referring to the 110V site tools that run through an isolating transformer. Neither pole of the 110v is grounded therefore the possibility of shock is reduced even if the tool's metalwork is not earthed.

That said, having the ground as well can't hurt particularly when you drill through a live cable

Thanks Crossy. That makes sense now.

IMPORTANT CORRECTION I believe my supposition that the 110V is completely earth-free is incorrect. It seems that the site transformers are actually 55-0-55 about earth. 55V is deemed a non-hazardous voltage

exactly

[jenkins]

hi guys

ive been busy , so haven,t replyed

after reading through this thread im not going to reply

some of you are obnoxious , and incorrect

to sum up--

12 volts is lethal

110vac is as "dangerous as 220-240

etc etc

i really havent got time for all this

ill leave you all to it

heres some laughs x100

Edited February 19, 2007 by jenkins

[elkangorito]

hi guys

ive been busy , so haven,t replyed

after reading through this thread im not going to reply

some of you are obnoxious , and incorrect

to sum up--

12 volts is lethal

110vac is as "dangerous as 220-240

etc etc

i really havent got time for all this

ill leave you all to it

heres some laughs x100

Touchy!!!

[Naam]

Touchy!!!

*****

i don't think he tried to touch the poles of a 12v batterie as suggested

[Crossy]

Touchy!!!

*****

i don't think he tried to touch the poles of a 12v batterie as suggested

Maybe, he's gone very quiet.

Whatever, WE know that if you treat electricity at any voltage with respect you stand a good chance of not getting zapped

Assume any cable is live until you've proved otherwise etc etc etc.

The point that miffs me slightly is the deliberate distortion of what we stated, we say "12V can be lethal under certain circumstances", he says "12V is lethal" which is most definately NOT the same. Arrrggghhh, what's the point?

[elkangorito]

Touchy!!!

*****

i don't think he tried to touch the poles of a 12v batterie as suggested

Maybe, he's gone very quiet.

Whatever, WE know that if you treat electricity at any voltage with respect you stand a good chance of not getting zapped

Assume any cable is live until you've proved otherwise etc etc etc.

The point that miffs me slightly is the deliberate distortion of what we stated, we say "12V can be lethal under certain circumstances", he says "12V is lethal" which is most definately NOT the same. Arrrggghhh, what's the point?

Fully agree Crossy.

I think many people seem to think only of the end result of getting zapped & not what happens (or can happen) DURING the process of getting zapped (burns, severe bruising etc). Of course, it has been proven that current of a certain magnitude, if passed through your heart, can kill you. And of course, this current can come from any voltage source. But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

Edited February 20, 2007 by elkangorito

[Khonwan]

..... But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

How many milliseconds does that last?? And how much longer than that would a clamped muscle take to release?

Khonwan (non-approved, or otherwise qualified, non-electrician)

[Naam]

..... But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

How many milliseconds does that last?? And how much longer than that would a clamped muscle take to release?

Khonwan (non-approved, or otherwise qualified, non-electrician)

a difficult question let me get my calculator... hmmm... here.... tip.. 1 sec divided by... tip.. 50 cycles = ahmmm... = 0.02 - now we have to find out how many milliseconds in one second click on google.... type in "milliseconds".... click... wait.... AHHHH! WHAT? one second has ONE THOUSAND milliseconds? that's indeed strange. was anyone aware of that?

we should all get together on my terrace, emptying a few bottles of Port or Sherry and then proceed to one of my wife's cars looking at the batterie. of course we won't touch it but go back to the terrace and shout loudly LET'S HAVE MORE WINE!

[Khonwan]

..... But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

How many milliseconds does that last?? And how much longer than that would a clamped muscle take to release?

Khonwan (non-approved, or otherwise qualified, non-electrician)

a difficult question let me get my calculator... hmmm... here.... tip.. 1 sec divided by... tip.. 50 cycles = ahmmm... = 0.02 - now we have to find out how many milliseconds in one second click on google.... type in "milliseconds".... click... wait.... AHHHH! WHAT? one second has ONE THOUSAND milliseconds? that's indeed strange. was anyone aware of that?

we should all get together on my terrace, emptying a few bottles of Port or Sherry and then proceed to one of my wife's cars looking at the batterie. of course we won't touch it but go back to the terrace and shout loudly LET'S HAVE MORE WINE!

Answer the follow-on question as well, smart ass!

[Naam]

"Answer the follow-on question as well,

smart ass!"

*****

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

[Crossy]

"Answer the follow-on question as well,

smart ass!"

*****

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

Ah but doc, IF the current is only just making it into the 'can't let go' value right at the peak of the sine, it MAY be possible to release in the time when it is below the 'can't let go' value (which could be 5ms or so), or there again it may not

I've not done any calculations, or investigated how long the muscles actually need to operate, or anything to be honest, 'tis just a thought

My ass is particularly smart, he knows where to find hay and carrots

[Tywais]

"Direct current (DC) is more likely to cause muscle tetanus than alternating current (AC), making DC more likely to "freeze" a victim in a shock scenario. However, AC is more likely to cause a victim's heart to fibrillate, which is a more dangerous condition for the victim after the shocking current has been halted."

The reasons being that if the heart is completely stopped, CPR can restart it. If it is fibrilating, it usually cannot and a DC shock (shock paddles) is necessary to put it back to normal rythym.

Source: http://www.allaboutcircuits.com/vol_1/chpt_3/2.html

[Khonwan]

"Answer the follow-on question as well,

smart ass!"

*****

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

Sarcasm does not impress me. Nor does rubbishing someones qualifications - I'm referring to your JIB jibes against an earlier poster. If you actually have a doctorate in physics, please apply your knowledge to better effect. Rise above your childish impulses and reflect the maturity of your age please.

My questions were rhetorical to allow you or the sparkies to correct elkangorito's statement. That would have been a greater service to this forum. I have detected in your replies that you do know that, whilst 100mA AC can kill, 300-500mA DC is normally required to do so within the same duration.

Two very good sources to settle the question of whether DC or AC is more dangerous:

"For an average 70-kg man, let-go current is about 75 mA for DC and about 15 mA for AC.": http://www.merck.com/mmpe/sec21/ch316/ch31...20dc&alt=sh

"Table B-1. Effects of electric current on the human body (Ref. 1).": http://www.llnl.gov/es_and_h/hsm/doc_16.01/doc16-01.html#tb1

[Crossy]

"Answer the follow-on question as well,

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

Nor does rubbishing someones qualifications - I'm referring to your JIB jibes against an earlier poster.

Just occasionally I get the urge

IMHO Our JiB registered sparks did ask for a bit of friendly tail-pulling, I'm quite sure his skin is sufficiently thick that he'll be back in fighting form

[Khonwan]

"Answer the follow-on question as well,

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

Nor does rubbishing someones qualifications - I'm referring to your JIB jibes against an earlier poster.

Just occasionally I get the urge

IMHO Our JiB registered sparks did ask for a bit of friendly tail-pulling, I'm quite sure his skin is sufficiently thick that he'll be back in fighting form

Fair enough. Love the animation!

[Crossy]

"Answer the follow-on question as well,

thanks for introducing yourself. nice to meet you... my name is Dr. Naam. i fully agree with you that the milliseconds at the sinus low will not allow to "uncramp" any muscles as "elkangorito" assumes.

satisfied?

Nor does rubbishing someones qualifications - I'm referring to your JIB jibes against an earlier poster.

Just occasionally I get the urge

IMHO Our JiB registered sparks did ask for a bit of friendly tail-pulling, I'm quite sure his skin is sufficiently thick that he'll be back in fighting form

Fair enough. Love the animation!

Yeah, I thought it fit quite well

[elkangorito]

Fully agree Crossy.

I think many people seem to think only of the end result of getting zapped & not what happens (or can happen) DURING the process of getting zapped (burns, severe bruising etc). Of course, it has been proven that current of a certain magnitude, if passed through your heart, can kill you. And of course, this current can come from any voltage source. But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

50Hz = one full cycle in 20mS. Since the 'zero point' occurs halfway through the cycle, the time elapsed at this halfway point = 10mS. Assuming that I am getting an electric shock but one that is initially not dangerous (low contact voltage due to a high skin resistance - assume an easy 'let go' voltage), I would have a very good chance of unhooking myself as the sine wave approaches & passes through the zero point, which is every 10mS. And as Crossy indicated, it may be between 5mS & 10mS. It may be interesting to note that RCD's for personal protection have a maximum operating time of 20mS.

[Khonwan]

Fully agree Crossy.

I think many people seem to think only of the end result of getting zapped & not what happens (or can happen) DURING the process of getting zapped (burns, severe bruising etc). Of course, it has been proven that current of a certain magnitude, if passed through your heart, can kill you. And of course, this current can come from any voltage source. But at the end of the day, I'd sooner get hooked up on AC than DC. At least with AC, I've got a chance to 'unhook' myself as the waveforms pass through the sinusoidal zero point.

50Hz = one full cycle in 20mS. Since the 'zero point' occurs halfway through the cycle, the time elapsed at this halfway point = 10mS. Assuming that I am getting an electric shock but one that is initially not dangerous (low contact voltage due to a high skin resistance - assume an easy 'let go' voltage), I would have a very good chance of unhooking myself as the sine wave approaches & passes through the zero point, which is every 10mS. And as Crossy indicated, it may be between 5mS & 10mS. It may be interesting to note that RCD's for personal protection have a maximum operating time of 20mS.

Thanks for addressing that narrow point but the statement, "For an average 70-kg man, let-go current is about 75 mA for DC and about 15 mA for AC.": http://www.merck.com/mmpe/sec21/ch316/ch31...20dc&alt=sh addresses the issue - surely you now agree? And its assertion is contrary to your message.

[elkangorito]

Maybe I'm wrong but as the voltage sine wave passes close to & through zero, minimal & then zero current will be flowing respectively. No current = no muscle contraction. My analogy relates to the muscle pulses I have felt when I have been zapped before. I do not dispute the AC & DC 'let go' values.

[Khonwan]

Maybe I'm wrong but as the voltage sine wave passes close to & through zero, minimal & then zero current will be flowing respectively. No current = no muscle contraction. My analogy relates to the muscle pulses I have felt when I have been zapped before. I do not dispute the AC & DC 'let go' values.

Fair enough. Thanks.

[Naam]

"If you actually have a doctorate in physics, please apply your knowledge to better effect. Rise above your childish impulses and reflect the maturity of your age please."

*****

this discussion is as superfluous as the tits of a nun or the nipples on a man's breast.

we should all agree that electricity can be very dangerous, lead to death and should therefore be treated with utmost caution. even my rather uneducated gardener possesses that knowledge. perhaps it's worthwhile to mention that he has neither a doctorate in any science nor is he a "jibbed" electrician.

[Khonwan]

"If you actually have a doctorate in physics, please apply your knowledge to better effect. Rise above your childish impulses and reflect the maturity of your age please."

*****

this discussion is as superfluous as the tits of a nun or the nipples on a man's breast.

we should all agree that electricity can be very dangerous, lead to death and should therefore be treated with utmost caution. even my rather uneducated gardener possesses that knowledge. perhaps it's worthwhile to mention that he has neither a doctorate in any science nor is he a "jibbed" electrician.

And another useless post (as indeed is this one, of course).