Replace old subpanel or not?
Friend had old main panel with 100amps and no spare spaces. Getting everything upgraded - new main panel with 200amps already done last month.
House is 100 years old with mixed knob& tube wiring and new NM romex wiring in parts that were remodeled. For example the kitchen was remodeled 4 years ago and since it was right above the service room in the basement, they ran all new wiring to the panel.
Currently, remodeling entire 3rd floor and contractor is putting a 16 space sub-panel on the 3rd floor to connect all the lights and breakers for the entire 3rd floor to include 2 bathrooms on 3rd.
In the Kitchen on the 2nd floor is a very old Square D QO 125 amp sub-panel with 8 breakers - I think it's fed from a 60amp breaker from main panel, but I don't remember size.
All of the wiring coming into this old subpanel is old knob and tube type. None of it is for the kitchen. Some of the breakers power the other old rooms on the 2nd floor which have old plaster covered walls. Some of it originally also powered the 3rd floor but is no longer needed, so on the 3rd floor the contractor cut the old K&T lines and put junction boxes wherever he cut the knob& tube wire since it is still live due to possibly going to other locations on the 2nd floor and basement and the Attic room on the roof. The entire 3rd floor was newly wired with NM (romex).
Back to the old 8 space subpanel in the kitchen. It is old - and it is working fine. Should it be replaced with a new one? They would simply be swapping out the old box with a new one and not adding any arc fault switches since it is all knob and tube wiring and has shared neutrals. Or should they just leave the existing old panel as is.
Cost is not an issue here since the panel is less than $50.
They will not be changing any of the knob and tube wiring feeding it since it goes to areas on the 2nd floor that were not remodeled at all so that will all stay.