What is a dummy dimmer?

A dummy dimmer is a 6 amp light switch that is made inside a dimmer casing. It looks like a dimmer, but is a standard two way light switch. Hence the name 'dummy dimmer'. 

Why would I need a dummy dimmer?

Standard dimmers are two way, but it is important you only put one dimmer on each circuit. Putting two messes up the signals to the light and creates a number of issues, but normally is manifested as flickering lights. On occasion you may have two dimmer plates in a room, but on one of the plates you need a standard light switch. 

It is also useful if you want to put a non-dimmable circuit, like a fan or an non-dimmable light, on the same plate as dimmers. It will look like the dimmer, but rotating it doesn't have any effect.