re.split?
'London, ENG, United Kingdom or Melbourne, VIC, Australia or Palo Alto, CA USA'
>>> list(map(str.strip, re.split(',|or', x)))
['London', 'ENG', 'United Kingdom', 'Melbourne', 'VIC', 'Australia', 'Palo Alto', 'CA USA']
>>> list(map(str.strip, re.split('or', x)))
['London, ENG, United Kingdom', 'Melbourne, VIC, Australia', 'Palo Alto, CA USA']
, or, . str.split:
>>> list(map(str.strip, x.split('or')))
['London, ENG, United Kingdom', 'Melbourne, VIC, Australia', 'Palo Alto, CA USA']
UPDATE
>>> x = 'London, ENG, United Kingdom / Melbourne, VIC, Australia / Palo Alto, CA USA'
>>> re.findall(r'(?:\w+(?:\s+\w+)*,\s)+(?:\w+(?:\s\w+)*)', x)
['London, ENG, United Kingdom', 'Melbourne, VIC, Australia', 'Palo Alto, CA USA']