Protect external sockets from moisture
Outdoor sockets are basically splash-proof and manufactured and suitable for various weather conditions. In winter when it's snowing and year-round in bad weather or heavy rain, but I'm never sure if they are really well protected and do not cause a short circuit.
All year round are in my outdoor sockets in addition radio sockets (for outdoor use) and in winter come for Advent and Christmas decoration additional radio sockets.
All systems have a flap that seems to protect against moisture. I can not really understand, because rain and snow is not always from the top, but also from all sides.
Fortunately, occasionally in heavy rain, the FI-switch shuts off the outdoor area from the power supply, so I now additionally secure my sockets and sockets when needed. The power failure was caused by moisture in an outdoor radio socket.
Protect the external socket from moisture
To secure the sockets, it only needs a sufficiently large disposable bottle. These are available as a 3-liter bottle often filled with sugar-free iced tea or as a 5-liter bottle with just such juice.
With a cutter or potato peeling knife, the selected bottle can be very well freed from the upper third (taper and closure) and can then be slipped over socket columns incl. Radio-controlled sockets.
If necessary, cut a slot laterally if the width is insufficient.
The bottle can be slipped over from above (photo 3) or attached laterally as in photo 2. The bottom of the bottle should be aligned against the rain side.
For wall sockets are also smaller bottles, which are slipped over from the front and possibly fixed with clear tape on the side of the surface-mounted socket.
General remark:
A RCCB protects people and animals from electric shock and is absolutely necessary for protection due to damage to electrical systems, defects or external influences.
A normal fuse is not enough to protect living beings from electric shock: it is too slow for that.
Residual current circuit breakers save lives and can be retrofitted. Buy now 
UNITEC 44244 socket outlet in stone look with 2 sockets and timer 32,94 ?
