David Ashe
Hi mark Firstly I would make sure the metal box has an IP rating this will ensure not water can get into the appliances. You appliance will have there own earth attached to them via the plug top and will be then attached to the metal case inside, if you wanted to be belt and braces you can run 6mm earth bond to the metal outside box, I would also make sure to the power to the appliances and on a rcd Hope this helps Kind Regards David Ashe Ashe Electrical Ltd
