No not normal. Likely there is water getting into the contacts on top of the poles - report it as an intermittent fault and mention that . It's down to OR to fix if that's what it is. Or if your lines are underground water is getting in somewhere.
Unless theres water pouring out your master socket then the onus is on them. I worked for years doing faults. It might have changed but that's what I would do
Edited by pcoventry76 (Fri 19-Oct-12 14:24:48)