Almost garage fire!

Last weekend my garage almost caught fire! The sum of current drawn by the electric heater and the dremel, radio and mobile charger was to much for the old multiple socket outlet. Luckily I smelt a strange aroma! I checked the wires of all connected items and some of them were almost too hot to touch! So, I unplugged everything directly.
First thing I bought a new multi socket outlet with incorporated fuse and a far more robust design, I hope not to face this risk again. Of course, I will connect the electric heater in another, separate fused outlet from now on!

This is the new multi socket outlet:

with switch and fuse:

So, what went wrong? Let's check the old one: Looks normal at first sight:

 one of the 4 pairs of contact bars shows a different color (bottom right):

those contact bars and the connection to the cable must have been veeery hot: 

 upon closer inspection: This is a "normal" locator pin and contact hole:

this is the other one: locator pin and contact hole totally molten, the contact area has burn marks:

I think I was lucky to "smell the problem"

Guys, check your power supply and watch for overall current consumption!!! A max. of 3500 Watt is the limit, with good cable and no spools in the extension cords!
Wrench safely!!!