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