Neutral to Earth voltage

[Sanath Embedded]

Hi,

Could anyone tell me what has to be voltage b/w Neutral to earth.

I have the system which when I connect , it shows around 106Volts b/w neutral to earth.

Line-Neutral Voltage Line-Earth Voltage Neutral-Earth Voltage
227VAC 120VAC 106VAC

Thanks in advance

 

[FvM]

Neutral is not guaranteed to have an earth connection. I know, that in some countries with 120 VAC voltage standard, it's common to connect two 120V transformers to generate 230/240V, with center tap earth connection. Or you have an isolated transformer secondary.

 

[prince213]

Line - Neutral Voltage = Supply Voltage

Line - Ground Voltage ~ Supply Voltage (For testing purpose only)

Neutral - Ground Voltage ~ 0V (Theoretical, but practically it should be around 2 - 6 V)

Neutral - Ground Voltage value depends upon the quality of Earthing, a lower value is always preferred. If its high which shows there is some problem with earthing, this can result in electricity passage over device cabinet, casing etc which may result in malfunction & can even give shock to the operator.

 

[chuckey]

The neutral conductor carries the return current to the supply transformer. Depending on the current, length and resistance of the Neutral conductor, the neutral to earth voltage can be up to 10V. In America where there is a 115-N -115 supply, any differences between the currents taken by the two 115 V supplies flows down the neutral. There would be no neutral current with 230V loads.
Frank

 

[DXNewcastle]

To develop FvM's post, it is actually very common for generating sets to use a centre-tapped earth. These may even be used to provide power to installations which are usually supplied from the local supply and this means that their voltages can be unpredictable.
With a centre-tapped earth, the neutral - earth voltage is the same as the live - earth voltage. (and both of these are half the live - neutral voltage).

In places where this DOES NOT apply, then the neutral - earth voltage should be very low, as others have posted, but there are several reasons why it can vary substantially, particularly when the load on the 3 phases is very unequal. The heavily loaded phases will "pull" the neutral voltage towards them. In fact the voltage distribution across 3-phase supplies can become quite complex and we should never make assumptions about neutral being "safe". It isnt.