Work on fixed installations (faste installationer) has to be done by an autoriseret elinstallatørvirksomhed (authorised electrical firm). Ask whether they hold the authorisation themselves or bring someone who does, and get that on the invoice.
Herning is mostly houses and business premises. Distances inside the municipality are longer than in a dense city, so the drive is often a clear line on the quote. The same 4 businesses as the Danish page: Borre Elteknik ApS, HAMMERUM EL A/S, KS Industri-El v/Kenneth Sonne-Schmidt, PC El-Service ApS.