Low-Voltage Wiring in a Single-Family Dwelling - Speaker, computer, and telephone wires can be installed by the homeowner. No license is required, but an electrical permit (PDF) must be pulled, at a cost of $35
Smoke Detector Requirements - Any smoke detector located within 20 feet of a kitchen of 20 feet of a bathroom containing a tub or shower shall be a photo-electric type (780 CMR 3603.16.11) When 1 or more sleeping rooms are added or created in existing dwellings, the entire building shall be provided with smoke detectors designed and located as required for new dwellings