Singapore legislation
Regulation 20
Regulation 20
Use of auto-transformers
Subregulation 1
When installing an auto-transformer in an electrical installation, a licensed electrical worker shall take suitable measures to ensure that —
the lower voltage system in such auto-transformer will not be accidentally charged above its designated voltage during the use of such auto-transformer by leakage from or contact with the higher voltage system of the electrical installation; and
the voltage between any part of the lower voltage winding of such auto-transformer and Earth shall not, at any time during the use of such auto-transformer, exceed the voltage between the terminals of the lower voltage winding of such auto-transformer.
Subregulation 2
No person shall use an auto-transformer to supply electricity to —
a socket-outlet;
a portable appliance, unless the auto-transformer is contained therein;
an electric toy; or (d)any extra-low voltage circuit.