AC Current

[Brad Ford]

OK, maybe not a sparks question but with an AC supply, why do appliances have phase and neutral wiring?

Would it matter which way round they are wired at the plug e.g. A vacuum cleaner?

A simple question, but remarkably difficult to get a definative answer.

Thanks in anticipation.

 

[PC Electrics]

Most appliances will work fine if they are wired with incorrect polarity. However for class I items this is extremely dangerous as the fuse can end up in the neutral. If the fuse blows in these circumstances then the item is still live - potentially it could have a live casing. Also switching ends up in the neutral which means motor windings and lamp connections etc stay live all the time (so they are never really "off" properly).

 

[Ian Speirs]

If the fuse blows in the plugtop then the appliance will be disconnected from the supply. But if the appliance has an internal fuse and this blows, then the load side, which is intended to be disconnected in the event of a fault is still live as the supply is coming from the other direction through the neutral side first. And as PC Electrics said "switching ends up in the neutral which means motor windings and lamp connections etc stay live all the time (so they are never really "off" properly)."

 

[Evans Electric]

As said above , the fuse and the switching could be in the neutral so the whole device is always live .

 

[ADS]

OK, maybe not a sparks question but with an AC supply, why do appliances have phase and neutral wiring?

Not sure I fully understand this part of your question, but without phase and neutral wiring, they wouldn't work.

The phase (or line) has an alternating voltage which changes from +320v to -320v at a rate of 50 times per second.

The neutral is referenced to earth and so remains at 0v.

The difference in potential between the line and neutral conductors causes the current to flow.

When the line conductor is at +320v, the current will flow from the neutral to the line conductor.

At -320v, the current reverses, flowing from the line conductor to the neutral.

Hence, alternating current.

Hope that explains

 

[Brad Ford]

Thanks for the responses, much appreciated.

 

[sparkytim]

Not sure I fully understand this part of your question, but without phase and neutral wiring, they wouldn't work.The phase (or line) has an alternating voltage which changes from +320v to -320v at a rate of 50 times per second.

The neutral is referenced to earth and so remains at 0v.

The difference in potential between the line and neutral conductors causes the current to flow.

When the line conductor is at +320v, the current will flow from the neutral to the line conductor.

At -320v, the current reverses, flowing from the line conductor to the neutral.

Hence, alternating current.

Hope that explains

Which country is this voltage then?

 

[ADS]

Which country is this voltage then?

This country - approximately - it should actually read 325v (sorry)