I was changing some outdoor lights. I had the circuit breaker off (which stopped the lights from working) and the switch off. I used a contactless circuit tester and a testing screwdriver which suggested there was no current.
When working on the live wire I felt a slight buzz - not strong enough to call it a shock - so I shorted it to ground with a screwdriver and there was a spark. After that there is no more buzz from the wire and nothing tripped.
Given the circuit breaker is off how was it possible to get a very small shock from the live wire? Is it residual charge in appliances on the circuit discharging? Is there anything one should do when working in this situation?