- Processing of plug and socket. Both are here made of rubber and not brittle plastic. The connector will not budge in the clutch, which is also very important. Did he namely game and is loose, it may come due to high contact resistance for braising clutch and / or plug in the worst case.
- Cross-section of the cable used - here 1.5 mm², ie top. There are also cables with only 1 mm², and I'd rather not use 3000 W beyond. By the way is on every cable of cross-section, z. B. "3G1.5 mm²", said 3G is simply that the cable has a ground wire. . Thus, even if, for example, is indicated on the package no cross section - on the cable itself it is always. Useful in open-label extension cables in the building or supermarket.
- VDE and / or GS mark. VDE has this cable. If the VDE mark is present but no GS mark, which is not a cause for concern. The other way around, I see the same thing. Only if neither of these characters is present, I would rather leave it alone.
- Information on the maximum load capacity, eg "250V / 16A" or "max 3600W.".. 16A correspond to about 3600 W, and are also the maximum load that can withstand any normal household socket and any conventional 16A circuit breaker. This information can be found in fact on each extension.
Everything I have described here, by the way just as valid for multiple sockets / power strips. Never wire or strip with a cross section less than 1.5 mm² buy!