Range from the cheapest fitting of a smoke alarm £64 (Sam electrical based in Nw1) to the dearest fitting of a smoke alarm £184 (The Kensington Plumbing and Heating Specialist based in SW7).
Comparing electricians estimates for fitting smoke detectors gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to fit a fire alarm in W9 by posting a job with HaMuch and we will send it to electricians in W9.