Most of the Control panel-manufactures used to connect all the panel doors to the Earth bar provided inside the panels. Some clients demand for earthling rear panel covers. Is there any logic behind this demand? It is an added safety to earth the rear covers of panels also. Generally we do not do this as rear covers are screwed permanently and as such while we access the rear covers, the panel would be made dead and hence no danger. The standards and rules say that each touchable metallic parts should be earthed, so the rear cover, even screwed, can be touchable it should be earthed.