This section is mainly concerned with the “electrics” in your home, that is, the CONSUMER UNIT, or DISTRIBUTION BOARD (the unit with the large ON/OFF switch), the various combinations of circuit-breakers, or fuse cartridges within it, and the wiring, plugs, and sockets.
Obviously SAFETY is of prime importance when investigating ANY electrical problem, and NO-ONE SHOULD EVER WORK ON LIVE WIRING AT ANY TIME. Again, I will point out the DISCLAIMER on this site.
From time to time, you may need to monitor, say your washing machine, after replacing a drive belt, with the cover off. You must ensure that you are not exposed to, and do NOT TOUCH any exposed wiring or contacts. You will find that most manufacturers have recessed push-on contacts, or plug/socket arrangements for a lot of internal parts of home appliances, but this is by no means consistent and universal.
Always ensure that any appliance you are working on is protected by the correct fuse in the plug, and where possible on a circuit protected by an RCD (used to be called ELCB).