My elderly neighbour was telling me last night that her portable electric fire (fairly ancient by the sound of it) almost caught fire the other evening on its first outing since last winter. She had it on in her bedroom and her son had bought one of those plug-in RCDs (I have them too) to prevent any accidents, as her wiring is (I think) from the 1950s. Actually it was sparking and smoking, but no actual flames, thank goodness. I thought that an RCD would detect such a serious fault and shut the power off, or do they really only guard against shocks? (Her son has arranged for an electrician to come round on Saturday, by the way, just to make sure all is well with the wiring.)