Hello
My understanding is that it is unwise [possibly hazardous] to add an earth connection to an AC/DC set. The chassis may well be on the live side or neutral side of power input.
In certain designs including AC/DC communications receivers the chassis may be isolated from either side of the power input in which case it is safe and may, indeed, be desirable, from reception point of view, to connect an earth to the designated terminal or socket.
Adding an earth connection to a model designed for AC mains only [where there is a mains transformer providing isolation from the national grid] it is safe and could again be desirable from a reception point of view to connect an earth to chassis.
Such a connection need not be via the mains lead but via an extra conductor to an earth spike into the soil or to a water pipe [not plastic or alkathene].
Most AC only sets provide an earth terminal or wander plug socket which effectively earths the chassis when connected.
Ian Rose
