The element is fully screened and self-regulating. It is laminated between 2 layers of polyester reinforced aluminium foil.
Installation is easy: Place the mirror on a flat firm surface with the reflective side down and if necessary with a suitable cleaning agent such as cleaning spirits and allow to dry.
Take the mirror demister out of its self-adhesive side in the desired position against the back of the mirror and press and rub the entire area with a soft cloth until the unit is firmly attached to the mirror.
The 230V units must be connected to earth and protected by an earth leakage circuit breaker (ELCB).
12 Volt units must be powered from an isolation transformer.
Works really well. It’s a treat to look into a clear mirror after my shower!