There are many other likely cause of compressor failure besides voltage problems. A replacement compressor on an existing system is statistically much more likely to fail than the compressor on newly installed system merely because the condition that killed the first compressor goes uncorrected when the compressor is replaced. The next compressor is killed the same way the first one died. Also, compressor burnouts can heavily contaminate a system and unless countermeasures are installed at the time the replacement is installed, contamination will doom an otherwise good replacement compressor to an early death.
Good ways to kill compressor:
- Liquid flood-back
- Inadequate oil return / lubrication
- Operating temp is too hot (compressor portion)
- Operating temp is too hot (motor portion)
- System contamination
- Incorrect electricity supplied (single phasing, voltage too high, frequency too low).
Of these possibilities, over-current problems caused by inadequate wiring is only one possibility for cause #4. I doubt this is your problem because virtually all residential units have a hermetic compressor with internal thermal protection for the motor winding. If this were the cause of your failures, the compressor would periodically stop for 15-30 minutes to cool down every time the winding overheated and it would do this many many times before the compressor motor burned out. You would probably notice this.
A compressor on a correctly functioning system should easily last more than a decade and likely more than 2 decades. Eight repeat failures on one system in one year is Keystone Cops level ridiculous. You need a more skilled technician to identify the underlying cause of the repeat failures.