There is no need to replace EXISTING consumer units unless defective or otherwise unsuitable for continued use. You do not need a metal consumers unit unless you are replacing the entire old one for some reason e.g full rewire. You can still make alterations to the existing wiring and leave ...
but it's a bit weird structurally. It consists of one section built on top of crawl space, and another section built slab-on-grade. Connecting the two is a small hallway and utility closet, which also has the water cooler, HVAC system, washer/dryer, and circuit breaker box. ...