Unpraktischstes Example: Since the inserted plug can be very difficult to pull it out again, you have to hold the cube forcibly so that it does not jump out of the holder. Well, we believe it is due to the strong forces to be employed permanently anyway ...
Nevertheless, the holder is practically in a certain way, when one side screwed him eg in some distance from the ground to the wall or in a piece of furniture, then plugged into the transformer plug before as moisture are protected from wiping or damage caused by contact with the vacuum cleaner. And as a pro-forma fixation eg against falling of cupboards helps the holder of course.
If the loss of a connection can be verschmerzt, clear recommendation, especially since the holder is relatively easy to install on wall or furniture.
Alternatives to mount? Exposed junction box from the hardware store, the approximate the surface of the cube - 8x8cm - has (eg something like Amazon: Junction box IP55 white ND01 AF20PW).
Since the plug does not fit through the branch holes, you have to cut to match the corresponding side of the case. If you have the box so prepared, it continues:
1 junction box on the wall / furniture screw / fix.
2. Are the dimensions of the junction box slightly smaller than that of the cubes, you can omit the cover and simply stuck to the cube for example with silicone and it is ready.
Otherwise, as in the example branch box, you have to cut the junction box and pulling through the cable from the PowerCube a relatively large hole in the lid center (!). A large hole is required, so that the connector fits through.
Then you close the junction box, then pulls the PowerCube zoom to box and fixed it on the cover, eg with silicone.
As adhesive should definitely choose a product that you possibly can remove again ...
Otherwise this PowerCube version is of course excellent, because it can be used etc. hesitation in Germany due to the VDE test seal.