Hong Kong Regulations

ELECTRICITY SUPPLY REGULATIONS - REGULATION 10

Connection of transformers with earth

The metallic portion of every high pressure transformer, with the exception of
the conductors thereof, shall be efficiently connected with  earth except in
respect of transformers supported on poles at such a height as to be
inaccessible except by the use of a ladder or other special appliance:
Provided that in such cases such poles shall be efficiently connected with 
earth.