The 1914 address book for Kattowitz lists Ernst as a businessman at Meisterstrasse 11. The 1928 telephone book list him at the same address (Meisterstrasse was renamed as Szopena in Polish), and names him as the co-owner (współ.) of Czwiklitzer i Haferkamp, a business involved in the electrical bonding of steam boilers (elektryczne spajanie kotłów parowych, Elektr. Dampfkesselschweisserei) with offices in Kattowitz at Dwozcowa 17 and Podgorna 5, and in Beuthen at Dyngostrasse 30.