This Appliance Must Be Earthed.

Ah, a gentle pootle around the maintenance workshop today. I was trying to explain to one of the maintenance men about what Blipfoto was; he still wasn't convinced after my explanation that it was worth taking photos in there. However, the parts and appliances they see every day are novel and interesting to me. I don't know what these thingies are, but they MUST be earthed. It says so, right there.