Tumble dryer trips the switch

[Pinnacle]

I have a double plug socket in the back room (lean to).
I have a lamp running off of it and has been working since I put it in there.
However when ever I try and run my tumble dryer off of the same switch it starts and then 10 seconds later trips the switch.

I've had a look at the socket but can't find any loose wires or any bare wires that maybe earthing themselves out.

The socket is the dual plastic box type.

 

[JohnD]

what is the "switch" that you mention?

where is it, how big is it, what letters and numbers are on it, does it have a "T" or "Test" button?