Voltage Fluctuation

A very strange behavior is observed in voltage since last night. We have three phase connection. Suddenly all of our ACs stopped working. When I checked voltage from DB, the voltage was normal 220 volts. As soon as any AC compressor starts the voltage drops below 100 volts and AC stops. All other appliances including fridge, fans, lights are normal. We have checked from neighbors and their voltage is normal. Can any expert help to identity / solve problem ?

How many ACs you have ?

Are they installed on different phases ?

Do all of them cause voltage drop when turned on ?

It looks like a contact problem, for example loose wire in circuit breaker. Most likely you have loose Neutral wire if all ACs behave the same.

Yes Ijaz Bhai, I have 6 ACs but normally 2 remain in service at a time. Two ACs installed on each phase and all of them are causing voltage drop. One thing more that from meter to DB there is underground wire through conduit. Last year our neutral wire got damaged resulting in damaging of running ACs. After that we replaced with good quality wire. The electrian earthed our neutral wire by drilling local bore.

If all of them are causing same issue and they are distributed on different phases, then it is neutral wire. This neutral wire might be loose in your house DB or from the pole.

OK. I have called LESCO to check.

Yes Ijaz Bhai, problem was exactly same as you identified. There was loose connection in meter. Probably intentionally done by Lesco for Edi. Thanks a lot.