At the moment, I have a TNS earthing system at home via sheath cable.

The Ze measured at the supply of the house is 37 Ohms, when it should be below 0.8 Ohm

As a consequence, I am going to convert to a TT system, with fully insulated consumer units and all RCBOs.

One question, I read that the Ze for a TT system should be below 200 Ohm

Do I need the earth electrode or can I use in the TT system the same cable sheath connection that has a much lower Ze?

Thanks,

Antonio