cant work this one out! Help please

[mattysupra]

Live and neutral need to be the correct way round for most things to work dont they?

A normal 240v light bulb can be wired either way but a transformer needs to be wired the correct way? Or a hoover for instance as it will blow rather than suck? Is that correct?

If so, how come abroad they have 2 pin plugs that can be used either way around?

 

[ban-all-sheds]

Live and neutral need to be the correct way round for most things to work dont they?

No - not most things, only single-pole switches, single-pole MCBs and RCBOs and fuses.

How could it be otherwise when the voltage of live with respect to neutral varies from +325V to -325V 50 times a second?

A normal 240v light bulb can be wired either way but a transformer needs to be wired the correct way?

No.

Or a hoover for instance as it will blow rather than suck? Is that correct?

No. How could it be when the motor is designed to work with the polarity of the voltage across its terminals changing 100 times a second?

If so, how come abroad they have 2 pin plugs that can be used either way around?

Because it's not so.

 

[mattysupra]

so a light bulb cant be wired both ways or a transformer can be wired both ways?


And what do you mean ..
Quote:
If so, how come abroad they have 2 pin plugs that can be used either way around?

Because it's not so. ??

 

[ban-all-sheds]

so a light bulb cant be wired both ways or a transformer can be wired both ways?

Both can be wired either way.

And what do you mean ..
Quote:
If so, how come abroad they have 2 pin plugs that can be used either way around?

Because it's not so. ??

I mean they have 2-pin plugs which can be used either way around because none of your assertions about polarity are correct.

i.e. it's not so in your "if so".

 

[Goldberg]

so a light bulb cant be wired both ways or a transformer can be wired both ways?

Both a light bulb and a transformer can be wired both ways.

And what do you mean ..
Quote:
If so, how come abroad they have 2 pin plugs that can be used either way around?

Because it's not so. ??

He means that your premise, i.e. "If so", is incorrect.

 

[mattysupra]

thats what i thought but got confused by this post..

ttony2 wrote:
Does it matter if I get them the wrong way round.

Depends what kind of light it is. Does it contain a transformer? If yes then you don't want ot get it the wrong way round. If there are no markings on the fitting then it might be able to be wired either way. Have you got a link to the light?

 

[ban-all-sheds]

ttony2 wrote:
Does it matter if I get them the wrong way round.

If you quoted it properly we'd get a link to it...

 

[Goldberg]

Does it matter if I get them the wrong way round.

Depends what kind of light it is. Does it contain a transformer? If yes then you don't want ot get it the wrong way round. If there are no markings on the fitting then it might be able to be wired either way. Have you got a link to the light?

 

[mattylad]

Matty, have a look up on how "AC" works.

 

[TicklyT]

Typically, single phase AC supplies use two conductors, and both should be considered live conductors.

Functionally, AC appliances don't care which way round these two conductors are connected, but it does have safety implications.

For various reasons, electricity supply companies try to maintain one of the conductors as near as they can to earth potential, and most refer to that conductor as 'Neutral', and the other conductor as 'live' or 'phase'.

In the UK, where ring final circuits are the norm, plug top fuses are fitted to protect appliance flexes etc. It's desirable to use a plug that only fits one way round in the socket, so the fuse is always in the 'live' conductor. The neutral conductor is considered less hazardous as it's potential should not vary much from earth potential.

In other countries individual sockets may be protected by fuses elsewhere in the fixed wiring. As the plug is not fitted with a fuse, a symmetrical plug which fits the socket either way round can be used.

Note this is a different issue to 'polarity'. Polarity is a property of DC systems, as used in automotive applications.

 

[securespark]

Note this is a different issue to 'polarity'. Polarity is a property of DC systems, as used in automotive applications.

Although when Line & Neutral are reversed, we call it Reversed Polarity...

 

[TicklyT]

Note this is a different issue to 'polarity'. Polarity is a property of DC systems, as used in automotive applications.

Although when Line & Neutral are reversed, we call it Reversed Polarity...

That's probably where the confusion starts.... It's a convenient but inexact term to descibe a situation.

Is it a leftover from those good old days of local DC power generation and distribution?

 

[Goldberg]

That's probably where the confusion starts.... It's a convenient but inexact term to descibe a situation.

That's just nonsense - it's an ordinary word with a precise definition that perfectly suits its use in describing power distribution.

Is it a leftover from those good old days of local DC power generation and distribution?

What do the opposite poles of any given magnet have, if it's not polarity?

Typically, single phase AC supplies use two conductors, and both should be considered live conductors.

Take those two conductors and touch each one to an earth - the one that goes BOFF is called the live, and the other isn't.

 

[rebuke]

In the regs both conductors are considered live - the one that is typically described as live is actually termed the line conductor...

 

[Goldberg]

In the regs both conductors are considered live - the one that is typically described as live is actually termed the line conductor...

You can sit in an ivory tower and term it whatever the **** you like - it's still called "the live" by the overwhelming majority of the population.

And for every single manufacturer's document that you can find using the words "line", or "switched line", I'll show you a thousand that say "live" instead.

If you insist, pendantically, on using a term that you know will confuse most people, then you're knowingly introducing a dangerous degree of confusion.