Hi, been to a job today and it was a funny one! The rccd was tripping! Found fault to be on down ring main! Unplugged everything and it stayed on! I then plugged in their 4 way surge protected extension bar and it tripped immediately! Nothing was plugged into the bar! So a faulty extension bar! Left the house and was stopped by a neigbour saying there power was tripping too! I went in and to cut a long story short found they had the same problem, a surge protected extension bar causing the rccd to trip! Never had this before? How do these surge protecters work and how would it cause the rccd to trip?