If you want to protect the equipment then the surge arrestor should be connected to the line and then by a jumper to bushing . The arrestor should be placed as close as to the transformer . In few cases the arrestor is mounted on a metallic support fixed onto the arrestor . The only care to be taken in is to see that when the arrestor fails ( blasts ) , the fragmented pieces of the arrestor should not hit the bushing ( if you are not using blast proof type arrestor ) which may otherwise cause more damage .