[0] Advantages [TT] Safe and reliable [IT] Continuity of operation, cost [TN-S] Safest [TN-C-S] Safety and cost [TN-C] 
Cost
L o w
N o
L e a s t
H i g h e s t
L e a s t S a f e
H i g h
B r o k e n n e u t r a l
C o s t