http://www.ebay.com/itm/Dimmer-Schnurdimmer-fur-Lampen-Gluhlampen-KAOYI-KFD-527G3-75-300W-220-240V-/171372720992
Looks like - with the cables placed to the right - the upper cable is mains input and the lower cable the dimmed output.
There is also alleged to be a small fuse inside - you have to spring the case apart to get to it.
http://www.savemylight.co.uk/kfd527gb.html/
Stay safe...
January 2015