Dear all, THX so much,
I really appreciate all your investigation and recommendation. thats all true. The previous owner obviously didn´t ordered this regular inverter from Amel.
Until today I also can´t find any special inverter switch on the Gen panel, also nothing in engine room close to the chargers. As 2 years ago our 100A Mastervolt charger died,I made the mistake not to order an Mastervolt Mass Combi Charger/Inverter. sh... happens. 
The both small blue Victrons under the chart table I recognized already, just for mobil charging and onboard computers and TV set...Too slim for regular housekeeping devices, so we use a watercooker to boil our daily amount of hot water for coffee and tea. Then we keep it hot until next day in a Thermos jar.
Now if we are all together let me ask an other issue: our Corian worktop beside the sinks got a crack about 15 cm. Is there any possibility to repair or filling up with identical material without need to exchange the complete worktop? Corian is an artificial composite material, so should be able to repair from surface down?
Any suggestions and ideas are very warm welcome. THX!

Ulrich
"Soleil Bleu" /AM54/#88