How to Size a Mirror Defogger Pad

What size of defogger pad do I need?

Cover the part of the mirror people look into after a shower, not the whole glass. Standard pads in our range include 300 x 300 mm, 300 x 400 mm and 300 mm round, and pads can be made to custom sizes for larger mirrors.

How much power does a defogger pad use?

Multiply the pad area in square decimetres by its power density. Our pads are listed at 1.5-2.5 W/dm². A 300 x 300 mm pad is 9 dm², so about 13.5-22.5 W. A 300 x 400 mm pad is 12 dm², so about 18-30 W.

How warm does the glass get?

The pads are listed as raising the glass temperature by 10-20 °C, enough to keep it above the dew point of a steamy bathroom so condensation does not form on the covered area.

Which voltage should I order?

Match the mirror. Mains-powered mirrors use a 230V or 120V AC pad; mirrors running from an LED driver can use a 12V or 24V DC pad, provided the driver has the extra capacity for the pad's power.

How is the pad switched?

Wire it to a mirror touch switch with a defogger output, or to a relay, so it turns on with the mirror light or from its own touch key. Mirror switches with a defogger function are listed in our Mirror Defogger Pads range.

Figures are from our product listings or worked out from them. Check the specific model before installation.