General purpose distribution transformers are rated for 600 volts and below. They are generally used for supplying appliance, lighting, motorized machine and power loads from electrical distribution systems. They are either ventilated or totally enclosed, and are available with either aluminum or copper windings in standard ratings from 50 VA up to 750 kVA. Shielded distribution transformers are also available, which provide a copper electrostatic shield between the primary and secondary windings. The shield is grounded and thus shunts most noise and transients to the ground path rather than passing them through to the secondary.