North America Voltages

[Ramrod]

Originally posted by Lord Nikon
because not all plugs have 3 pins

[Ramrod]

Originally posted by Xaccers
In Saudi for instance they use two pin sockets, with no earth, and no gate to prevent an inquisitive 6 year old sticking the break cable from his bmx into it just to see what would happen



PS what happens is one of your fingers goes knumb and "mum's gonna kill me" goes through your head

not unless you kill yourself first.....

[Xaccers]

Originally posted by Ramrod
not unless you kill yourself first.....

*tries to remember all the times he's been electrocuted...

Originally posted by Xaccers
[B]We have three pins cos one of them is the earth to give a bit of protection.
A lot of appliances may have a three pin plug, but the earth pin isn't connected to anything, its just there to open the gate in the socket.

Really !!!!!!!!!!!! lol

when you get a mo, click on the "www" at the foot of my posts before you go any further

[danielf]

Originally posted by Xaccers
In Saudi for instance they use two pin sockets, with no earth, and no gate to prevent an inquisitive 6 year old sticking the break cable from his bmx into it just to see what would happen



PS what happens is one of your fingers goes knumb and "mum's gonna kill me" goes through your head

Yes, you get this on the continent. My brother once looked very surprised after sticking a long nail into a two pin socket. You can buy 'child locks' for two pin sockets. With the ones I know, you need to stick the plug in, twist, and push.

As for grounding, continental sockets in the kitchen/bathroom are grounded. They have a 'scraper' for the grounding. Any appliance that needs grounding comes with a plug that will only fit a socket with a scraper.

[Xaccers]

Originally posted by yesman
Really !!!!!!!!!!!! lol

when you get a mo, click on the "www" at the foot of my posts before you go any further

Things like my radio cassette player, electric shaver, amongst other things.
Ok, so they aren't exactly high voltage appliances, and they transform the AC to DC....

Originally posted by yesman
Really !!!!!!!!!!!! lol

when you get a mo, click on the "www" at the foot of my posts before you go any further

If you're in the electrical installation trade, why don't you give Xaccers a definitive answer. He is making a valid point...if the mains is ac, why should it matter if the pins are reversed?

Also why laugh at his comment about many appliances not using the earth pin?

[Jerrek]

Originally posted by XFS03
If you're in the electrical installation trade, why don't you give Xaccers a definitive answer. He is making a valid point...if the mains is ac, why should it matter if the pins are reversed?

Also why laugh at his comment about many appliances not using the earth pin?

I answered the question buckwheat...

[Xaccers]

Originally posted by Jerrek
Not quite. Yes it alternates, but one is the phase wire, and one is the neutral. You would want to be able to distinguish them from each other. Appliances with two pins, such as coffee machines, have one pin slightly bigger to indicate the phase wire. Since houses are wired with 2-phase power, you can create 220 volts AC by using two phase wires instead of a phase and neutral. That will create 110 v + 110 v = 220 v.

Ok so you've got two phases coming into the house (not sure about the UK and continental houses), so if you have any appliances that require 220V they can have a socket that supplies it.
But I'm guessing your ring main is just coming off one phase giving you 110V to all sockets connected to it right?
I'm just intreagued to know why it matters in north america whereas on the continent both pins on the plug are the same size so you can plug it in either way.

[Lord Nikon]

Originally posted by XFS03
If you're in the electrical installation trade, why don't you give Xaccers a definitive answer. He is making a valid point...if the mains is ac, why should it matter if the pins are reversed?

Also why laugh at his comment about many appliances not using the earth pin?

Ok, Lets start from the top

Mains is AC, however if you were to make contact with the neutral line, it is unlikely you would receive a major shock as this is not the line which hauls current, the current comes through the live wire, this is why the fusebox carries all the fuses on the live, not the neutral, In the appliance itself there is normally another fuse, again on the live, not the neutral. This is in case of a fault which connects the live feed to any conductive surfaces.


Secondly, the earth pin
Metal appliances normally use an earth in case something goes wrong which would result in a live wire contacting the body of the appliance, these use all 3 pins on the plug, this does not apply if the appliance is "double insulated"
Appliances which are double insulated normally only carry 2 wires, live and neutral, as the earth is not needed. Hence most power adapters have a plastic earth pin which only opens the gate on the power socket.


Incidentally Xaccers, in the UK we only get a single phase into the house delivering 240V

Originally posted by XFS03
If you're in the electrical installation trade, why don't you give Xaccers a definitive answer. He is making a valid point...if the mains is ac, why should it matter if the pins are reversed?

I did here
And as for this bit

Also why laugh at his comment about many appliances not using the earth pin?

The only part I was laughing at was this

We have three pins cos one of them is the earth to give a bit of protection.

The word bit seemed funny to me because that is your only protection against electric shock should a fault to earth occur.

As for the rest of Xaccers questions, they have been cleared up by other people.

[altis]

For at least ten years, UK mains has been nominally 230VAC. However, the tolerances are asymetric. I can't remember the actual numbers but it's something like +10% and -6%. If you stick a meter in a socket it will often measure 240V. The nominal voltage has been changed as part of harmonisation with Europe - which is on 220V.

The phase wire carries the current from the substation. The neutral carries it back again. Because the neutral wire has a small resistance, the potential at the appliance not be the same as earth. Remember Ohm's Law (V = IR). This is why we need an extra earth wire.

Originally posted by altis
For at least ten years, UK mains has been nominally 230VAC. However, the tolerances are asymetric. I can't remember the actual numbers but it's something like +10% and -6%. If you stick a meter in a socket it will often measure 240V. The nominal voltage has been changed as part of harmonisation with Europe - which is on 220V.

The phase wire carries the current from the substation. The neutral carries it back again. Because the neutral wire has a small resistance, the potential at the appliance not be the same as earth. Remember Ohm's Law (V = IR). This is why we need an extra earth wire.

OK, time to get technical..............

The voltage in the UK is 240 Volts AC + or - 6% tolerance
Assuming the tolerance is the same in europe we still come into line with the euro voltages anyway, that has always been the case.

As for neutral having a smaller resistance than the phase conductor is incorrect, they are both identical, resistance in a circuit is based upon the length of the cable, so as the phase conductor is run alongside the neutral conductor, they must be identical in resistance values as far as socket outlets (ring main)are concerned, and as for the earth wire, if the installation is what we call a "PME" installation, the neutral will be at the same potential as the earth wire, which also means that ANY extraneous fixed metalwork within the confines of a dwelling need to be "bonded" to earth electrically. eg copper pipes, rsj,s if exposed etc, to eliminate the potential difference between the general earth and the electrical earth.

On an installation where the incoming earth is connected to the sheath of the incoming cable is relied upon for fault current situations, there is normally a slight difference in potential between neutral and earth at the incoming point at the mains intake position in the house, as the neutral is connected to earth back at the suppliers sub-station, (or on a circuit within the dwelling, because the phase conductor has further to run than the neutral i.e. "the switching of the circuit")

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Fault currents these days are normally dealt with by a residual current device (RCD), this piece of equipment operates via the mains voltage running through it via phase and neutral, whereby a flux running around a coil within the unit is equal to each pole i.e. phase and neutral, if the flux running around either pole is upset (and I don't mean it cries), then it automatically trips out, then you realise you have a problem.

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Apologies to the powers that be if this is going slightly off topic, but I needed to present my case as some people are guessing about most of their answers.

[danielf]

Originally posted by Lord Nikon
Ok, Lets start from the top
In the appliance itself there is normally another fuse, again on the live, not the neutral.

To repeat Xaccers' question: then why, on the continent, are the two holes idential. You can plug the plug in either way, be it a grounded (with scraper), or non-grounded plug...

Originally posted by danielf
To repeat Xaccers' question: then why, on the continent, are the two holes idential. You can plug the plug in either way, be it a grounded (with scraper), or non-grounded plug...

This is normally the case with 110 volt circuits, which means 55 volts up each "leg" of the circuit, e.g. a 55 volt shock won't kill you, or in most peoples cases you wont feel it.

Now you are going to ask me why the uk is not on that system aren't you ?

Well, I think its a question of £ÃÆ ’‚£Ãà¢Ã¢â€šÂ¬Ã…¡Ãƒâ€šÃ‚£Ãƒââ‚ ¬Å¡Ãƒâ€šÃ‚£Ãƒâ€š £ÂÃâ €šÃ‚£Ãƒâ€šÃ‚à ƒâ€šÃ‚£ÃƒÆ’‚ £ÃƒÆ’‚£Ã ƒâ€šÃ‚£ amongst other things, which I won't go into here