Drilling or better not yet?

Now I have already tested many detectors and certainly belongs to the Bosch of the good, but I make basically states that you can not rely on these devices.
I had recently quite a large drill holes for a photovoltaic installation in walls (55mm). The unit was always (red, flashing) indicates that in the places where I wanted to drill, live cables were laid. This disconcerted me very much, then on to the said places no current-carrying lines are likely to be, etc. available. At most some distance some reinforcements.
After some back and forth I decided initially for a smaller pilot hole I tested step by step with an endoscope camera. There was no metal, cables etc. to find. The ensuing 55mm core drilling also yielded no cable, metal etc. although the unit had shown this. At first I thought, may indeed times, but in the next two walls I had exactly the same problem ... but here I chose the same core drilling carried out and to check afterwards whether lines, metal, etc. was available there.
That was certainly risky, but even in this respect it was found that no wires, metal etc. were available, despite the warning of the detector.

I had in which he had displayed lines other situations and in these references I was sure also to 90%, that here really live wires were, but in itself, I wanted the unit to Untersützung my subjective perception, rather than 'Estimate iron' the me even more insecure.

In our house there are brick walls, pumice, stone walls, concrete walls, post and beam construction and so on but I had been a really absolutely reliable indication of any wall.
I give 2 stars because it still was previously the detector still met with respect. Of the displayed values ​​into the Black soonest. Nevertheless, it is annoying when it provides a fairly reasonable display in a situation, and then on another wall suddenly the entire wall to contain eg live wires ...

It would be really great if some manufacturers in this respect would bring even a really good equipment on the market. I would pay for it even sometimes 1000,00 and more. Since being drilled pipes etc. are certainly no fun. But so far I have found nothing that really works reliably. Even the relatively expensive Wall scanner Bosch was a disappointment for me, because it gave little reproducible results with several test.
I must say that I bought the house 10 years ago and thus never know for sure exactly what are pipes etc.. Therefore, I had but I gradually many different detectors bought unfortunately they were all equally bad or Bosch as already erwäht, still the best in this respect.

In electrical installations but you can reference to wall outlets and existing switches, sockets etc. already estimate roughly where live wires should be present.
Unfortunately, this is but with copper pipes etc. completely different. And this is where even the Wall scanner failed Bosch. Thus, I did not dare until now in the bathroom to something
to hang a wall because my risk of being drilled aqueduct was too big and the whole detectors constantly changing did not provide reproducible ads / values.