We have a problem with induced voltage. We measure 220 VAC in the L and 45 to 60 VAC in the N. There is no chance of changing the cable. How to avoid this?

Normally the neutral wire of every circuit is connected to the neutral bus bar in the main breaker panel. Because the neutral bus bar is always connected to ground you should never be able to measure any voltage between the neutral wire and ground.

So, if you are measuring 45 to 60 VAC between the neutral and the ground it could be that the neutral wire has become disconnected at the breaker panel or somewhere in between the panel and the point where you are measuring that voltage.

Assuming the load equipment - an appliance, a motor or whatever - is still connected to the hot and neutral wires, then, if there is no connection to the neutral going back to the power station, in effect you are measuring the line voltage from the hot feed as reduced by the resistance and/or reactive impedance (total reactance) of the load. That could be making 45 to 60 VAC, as read by your meter, appear on the neutral wire coming back from the load.

A simple way to prove if that is the case is to unplug or disconnect all loads - appliances, light fixtures, motors, etc. - from the circuit in question. If you cannot then measure any voltage between the neutral wire and ground the next thing to check is the resistance between the neutral and ground.

First of all switch off the circuit by switching off the breaker at the main panel - or remove the circuit's fuse if it has a fuse and no breaker - and then use the resistance range on a multimeter to measure the resistance between the neutral wire and ground. If it is a very low resistance then an open neutral is not the cause of your problem. If it measures as a very high resistance or an open circuit then your problem is an open neutral.

The reason for the open neutral must be found and that fault must then be corrected urgently.

In the Discussion page to this question please let us know what you found when you did the tests suggested above, and whether or not this advice helped you to locate and fix this problem.

To be able to help you better it is important to know exactly here this circuit is located geographically in the world and to have confirmation whether - as inferred from your question - it is a 50Hz system with one 230V live and one neutral or whether it is actually a 60 Hz system having two 120V hots (+120V and -120V) balanced around neutral.

Then, if necessary we shall have to consider what other reasons could cause the fault you have described but to be able to do so it would help to know exactly what you found when you did the tests described above.

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.