Caravan blew fuse

has anyone else has this? I had indicators or stop light but when I had both together I blew the fuse.
It has a 10A fuse and think this is the right size.

10A is more than enough for 10 x 21w bulbs (2 brakes on car, 2 brakes on c'van and 6 indicators)
could be a dodgy bulb or damp / wet / short circuit in the trailing socket / c'van light fittings
try doing the same without the c'van lead attached, if fuse ok, you know your cars ok
then try do some basic fault finding, check the sockets are ok, and also take the lens covers off the c'van and look for water ingress

10 x 21w bulbs is 17.5 amps.
Even if your indicating and braking so 7 x 21w bulbs is on is still over 12 amps.

Car is fine. Temp fitted 15A and it works.
I don't think I will be overloading the wiring as it is two circuits and the spike in amps will be intermittent with the indicators being on and off as they flash.

I had somthing similar on my mk2 escort turned out to be a bad bulb holder shoring out on the left indicator but only when the side lights where on would it blow the fuse.