十 P 十 bn b bB aA∠-120 Z+Z P 十 ∠+120 十 P N aA+lbb+lcc =0 VN=0 NI 0 If we have balanced sources. balanced loads and balanced line impedance, a neutral wire of any impedance may be replaced by other impedance including a short circuit and an open circuitL p a n aA Z Z V I + = • •  =  − 120 + = • • • a A L p b n b B I Z Z V I  =  + 120 + = • • • a A L p c n cC I Z Z V I = + + = 0 • • • • I Nn I aA I bB I cC = = 0 • • N Nn Nn Z V or I If we have balanced sources, balanced loads, and balanced line impedance, a neutral wire of any impedance may be replaced by other impedance, including a short circuit and an open circuit.    a b c n • V an • + + + − − −    A B C • Z p Z p Z p N V bn • V cn • ZL ZL ZN ZL  = 0 • V Nn