Earthing Phase and Neutral

[noor.sddqui]

Hi Everybody
I would like to know that how to find Earthing and Neutral (with a multimeter)when the difference between Earthing and Neutral is 000 V. The voltage between Phase to Neutral as well as Phase to Earthing is same.And when all the three wires are of same conductor and same color code.(In the situation if I am not allowed to open the meter box).

Thanks & Regards

Noor A Siddiqui

[mbc]

as you should know about neutral and earthing and difference between them.

neutral comes from transformer and connected to neutral hole .( we have 3 wire high voltage and it goes to transformer= first part= and in second part we have low voltage 3wire with neural )
this transformer also have earthing system from his body to neural hole.
in house we have phase with neutral and earthing wire connected to neural in switch box
in building and all factories and .... we should have earthing holes with own wire
it is very important ohms between earthing wire and neutral wire it should be near zero and should measure by
meager mete
it is different for where your are using the earthing system
for factories less than 5
for labs less than 1
for equipment less than 2
for Thunderbolt less than 10
but about color
meanly earthing wire color is yellow with blue on that
but in neutral color each country has own rolls

[noor.sddqui]

Sir My query is that how to identify which wire is Earthing and which one is Neutral with the help of multi meter if the colorcode and conductor size of the wire are same.

[mbc]

ask some one who have permission to open the switch box
or put leak detector circuit break fuse between phase one and one of the those wire then wire one light lamp
and turn it on if you choose right wire the detector those not goes to off but if you choose wrong one the detector goose off . it means you have leak to earth .
in leak detector current of phase wire and neutral wire should be same if dose not it comes off.

[Tayters]

You could use an amp clamp meter on each of the wires. Guess you know that the live and neutral wires would take the same current and earth take no current.

If you can power it down you could also then disconnect what you might think is a neutral, power back up then that wire should have supply voltage on the end of it - same as a bad neutral on a breakdown call. If you did it on the earth then the wire would still be 0V. Wouldn't try that method if you have a 3 phase supply as a poor neutral there can damage circuit boards. Remember you will also have a circuit with no earth possibly so watch what you are doing. Amp clamp method bit safer.

Andy.

[chemi-cool]

isn't it more simple to follow the wires and find out which is which?

[mbc]

the method I told for one phase not for 3phase .
best way find some one who can open the switch box.

[Guner Edip Riza]

Dear All,
I may be changing the subject but in some countries they are still using the Edison`s electrical standards. Some times ago I was called to a buther's shop in order to clear an issue, the RCD tripping out.

The issue was that, the manufacturers of the there phase mincer did not use an earth wire, instead they have connected the natural direct to the chassis of the mincer.

[noor.sddqui]

Thanks guys. I have been refreshed on how a Phase and neutral are created....but none of you have answered my question.I know how to open a meter box but what will happen if the said situation arises that you are not been permitted to open the meter box.is there any method finding by multimeter.

[The Viking]

No........

[frank]

The issue was that, the manufacturers of the there phase mincer did not use an earth wire, instead they have connected the natural direct to the chassis of the mincer.

On a 3 phase unit, why would you need a Neutral. These are usually only need for the control circuit, not the motor.
The Earth connection is purely for protection against electrocution

[mbc]

yes frank you right , but if you have unbalance 3 phase you need neutral especial in star running motors .

[chemi-cool]

yes frank you right , but if you have unbalance 3 phase you need neutral especial in star running motors .

Where exactly you connect the neutral on a 3 phase star running motor???

[mbc]

it is not star -delta running motor .
it is just star running motors . or 2 star running

in star
L1=R=U L2=S=V L3=T=W
neutral=(U1=X)=(Y=V2)=(Z=W2)

in this case if your phase were unbalance it is better you connect neutral to central of your wiring in motors .

[GHAZ]

Hi I've never seen a neutral connected to a motor, which is running in star because in star you have L1,L2,L3 AT U,V,W and then you join Z,X,Y together to make a star point. Otherwise the motor won't run and they are balance d from the power station

[mbc]

of course because always you have 3 balance phase.

we are talking about unbalance system in unbalance system the star point is not zero point in this case if you measure it with neutral you see you have voltage and if you wire the neutral you can see and measure current and also you and see difference current in L1 L2 L3 so is better in unbalance system in star running motors we do it and mainly it is small motors .

in transformer we have high voltage and second part low voltage and also we have zero point and we wire it to neutral hole and also body of transformer is wired to earthing hole separately . why we wire our zero point to neutral hole because if we had unbalance system in our loads it does not effect to our zero point in out transformer.