A typical new domestic CU utilized as a main panel may have from 6 to 24 ways for gadgets (some of which may inhabit two ways), and will be divided into 2 or more sections (e. g. a non-RCD area for alarms etc., an RCD-protected section for socket outlets, and an RCD-protected section for lighting and other built-in devices).

Recent (pre-17th edition wiring guidelines) CUs would not typically have RCD safeguarded sections for anything besides socket outlets, though some older CUs featured RCD Incomers. Before 1990, RCDs (and split busbars) were not basic in CUs. Old rewirable-fuse boxes 1950s MEM rewirable fuse box (covered) 1950s MEM rewirable circuit box (open) 1970s MEM rewirable circuit box (covered) 1970s MEM rewirable circuit box (open) Fuse Boxes generally utilize cartridge or rewirable merges with no other protective device, and fundamental 4-ways boxes

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