Mains supply....Voltage measured between Earth & Neutral?

Mains supply....Voltage measured between Earth & Neutral?

.........is it zero volts?

Not necessarily, there may be a voltage drop up to several volts, depending on the earthing method. In case of wiring faults, neutral may expose a hazardous contact voltage.
https://en.wikipedia.org/wiki/Earthing_arrangements

Thansk FvM,

Your article confirms that Neutral is always directly connected to earth. (at some point)

So considering a mains powered bench power supply with a 2 pin mains plug................is it ever the case that inside the casing, the neutral will be directly wired to the output common?..............(so that the output common is earthed via the neutral)

The short answer is no. In the USA, the neutral is bonded to earth at the consumers inlet. In the UK the neutral is bonded to earth at the local transformer. Some variety of equipment in the UK is allowed without an earth wire because it is "double insulated". things like transformers are wound with special bobbins and all the wiring is properly insulated away from any metalwork or perhaps the whole case is plastic.
Frank

Thanks, this has a 2 pin plug (PSU) but is it double insulated?....spec doesnt say.

**broken link removed**

A double/reinforced insulation power supply should have the double square symbol. The shown power supply is equipped with a "Schuko plug" according to the datasheet, which suggests no double insulation. This means, your device might have been incorrectly modified to a cable/plug without PE connection.

Or the manufacturer has changed the design. In any case, there are several design features that makes the difference, e.g. transformer construction, clearance and creepage distances, additional ("double") insulation between metal case and mains circuit.

when i remove the schuko plug i will have to assess which is live and which neutral, because i must replace it with a 3 pin plug.........i suppose the only way to do this is to get another plug and bring out a bare earth connection from it, and then use voltmeter between earth and wire to see if it is live or neutral?

Re: Mains supply....Voltage measured between Earth & Neutral?

Use skrew driver with glow lump inside to identify live and neutral wires.

If you dont have Earth wire at all, then you have problem.

When you remove wall plug socket if there is one more wire, check it with lump teste to see for any case that is not live wire.

When you removing wall plug socket remove fuse from main fuse board for that socket in house. Check all wires with test lamp.

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Sometimes, in older bad building where people dont have ground in sockets at all (there is no wire for that in walls), often people connect ground to heating system radiator or water pipes, what is very very bad and very dangerous, specially in cases when we have malfunction of some device or badly installed wires, for example hot water boiler heater malfunction,....