basics of electrical supply

[prateeksikka]

hi alun!
i guess it is again a debatable issue .some people 220 V dc as more dangerous than 50Hz 220 V ac because 50 Hz wave gives u 50 chances of survival in just 1 second.....how about that.
About akash's point i have ultimately concluded that it is the power i.e energy dissipated into u in 1 second which makes u die and not just voltage or current.
in short it is V*I.

 

[Alun]

Oh sorry, I forgot to mention that DC is worse than AC because it causes your mussels to cease up, put simply the lower the frequency the worse it gets.

 

[prateeksikka]

hi alun!
also the skin effect also dominates at very high frequencies and does not damage the inner organs.
(considering body to be perfect conductor)...
;D

 

[audioguru2]

I disagree.
Your guts conduct a lot better than your skin.

 

[Alun]

Audioguru, you're supposed to be an expert and you don't even know about the skin affect : I drunk now andI still understand that electricity of a high frequency doesn't flow though the centre of conductors but passes thought the outside of skin. ;D

 

[audioguru2]

I think that the skin effect occurs at radio frequencies beginning about 1mHz, in the AM broadcast band.
I was up in an antenna mast in a tower with megawatts of microwaves there. I was given a microwave oven testing meter and was told that if it responded then to get the **** out of there as fast as I can. Those microwaves don't know about the skin effect because they cook you from the inside.

 

[MP1]

Oh sorry, I forgot to mention that DC is worse than AC because it causes your mussels to cease up, put simply the lower the frequency the worse it gets.

It is all dependent upon the current that runs through you to ground, not the voltage or frequency.

I have a board that uses about 1,000 volts DC. Zaps you pretty hard, but causes no damage. (...it certainly wakes you up).

MP

 

[prateeksikka]

hi MP !
I think the 1000V source about which u are talking might be haveing a high internal resistance which dissipates most of the power when u touch the source.
It does happen .Some lineman do repair high voltage lines with bare hands but internal resistance must be high otherwise god is the savior!!! ;D

 

[Alun]

dent upon the current that runs through you to ground, not the voltage or frequency.

I have a board that uses about 1,000 volts DC. Zaps you pretty hard, but causes no damage. (...it certainly wakes you up).

I am aware of this MP, I meant to say that your body is less affected by current at higher frequencies because it doesn't affect the nervious system.

 

[MP1]

hi MP !
I think the 1000V source about which u are talking might be haveing a high internal resistance which dissipates most of the power when u touch the source.

Prateeksikka, with a constant voltage source, resistance is what determines the amount of current in any circuit (V/R=I), including the body. Current is the same through a series circuit. Thus no matter which item, body or circuit, the total resistance of the circuit will determine the current.

MP

 

[prateeksikka]

Conclusion from my side :
A high voltage source with a less series resistance or a high current source with high parallel resistance kills u.in otherwords it is V*I.

 

[shekhar_dandya]

Hi,
Iam back again with my original question.
Suppose I remove the ground plate that's buried under my building in a 5 feet deep ditch.keep the earth terminal floating in air.ie don't use it.
Now
expt #1: I hold the live wire.Do I get a shock?
expt#2:A person besides me on the same ground now holds the neutral and I hold the live.Now we both get shocked.right?
Are my observations correct?
What's the conclusion?
If U remove ground,no shock as far as one person is concerned.
When 2 persons hold,circuit gets completed and we both have  a shock.
So what is the importance of ground?

 

[Yevgenip]

Well, When you hold a Live wire your body's electrical Potential increases. If you are completely isolated from any thing that has a different potential than you have at the moment (220V or 110V or whatever), Nothing will Happen. If you touch something that has a much lower potential than you, you will get shocked - the bigger the potential defference - the bigger the voltage gets. The strenghth and nature of the shock depends also on the resistance between you and the object with the lower potential, since the resistance effects the current and it is the current, not the voltage that creates the shock and may kill you.

So it is possible to get a nice shock from a 1.5v source, if the current is strong enough.

 

[aakaash]

So it is possible to get a nice shock from a 1.5v source, if the current is strong enough.

Yevjeni
No, from 1.5v human wont get shock; coz body-resistance is high enogh compared to 1.5v to produce that much current accrding to ohm's law.
Aakaash
India

 

[Alun]

You won't be able to get a shock from 1.5V but you'll be able to feel it if you apply it to your tongue or if you have a cut. In my experiance the lowest voltage I've felt with my fingures is 24V but that's because it was hot and my fingures were sweaty.

 

[audioguru2]

If there isn't any lightning around you, try touching both terminals of a telephone line with a single dry hand. You'll feel a tingle from its 51V if it is not in use.
Then have somebody call your telephone and the resulting ringing peaks of 178V at 10 Hz will make you smile, vibrate and jump away. The ringing is 90V/20 Hz but rides on top of the 51VDC, so the negative peak adds to the 51V each half-cycle. ;D

 

[Alun]

You might be zapped if your fingures are sweaty.

 

[aakaash]

From many days i have a question in mind .
When we use an Inverter in home , why does the voltage of inverter NOT go in neibour's home since Electricity-Board's wires are connected to all homes ?
Aakaash

 

[ante1]

Hi aakaash,

I don’t think it’s wired that way, it would be disastrous.

 

[aakaash]

Dear Ante
A pair of  Phase & Nutral wires come from street-polls to apartment and then all the homes in apartment get connected in parallal from that pair.
Aakaash