Yes when applied properly. Modern Romex (NM-B) cable is rated to operate within insulation; spray foam does not damage cable or create overheating risk at standard 15-20 amp circuits. Cincinnati installers air-seal around junction boxes and verify junction-box covers are in place before spraying.
More detail
Spray foam interaction with residential electrical systems is a question many Cincinnati homeowners ask, given the foam surrounds wiring in completed installs. The physics and safety considerations. (1) Cable temperature ratings. Modern NM-B (Romex) cable is rated for 90C continuous operation (a safety margin well above the 60C that typical residential loads produce). Cable buried in insulation runs slightly warmer than free-air cable, but not enough to approach the temperature rating limit at standard 15-20 amp circuit loading. (2) Cable derating for ampacity. The NEC (National Electrical Code) requires derating cable ampacity when it is bundled or buried in insulation, but for standard 15-20 amp circuits the derated capacity still meets the circuit's rated load. Cincinnati electrical inspectors look for ampacity issues during permitted work but rarely flag spray-foam-encapsulated NM-B as a problem. (3) Junction box clearance. Code requires junction boxes to be accessible for future maintenance. Spray foam should not be sprayed inside open junction boxes; the box cover should be in place and the foam sealed around the box exterior. (4) Recessed light fixtures. Pre-IC-rated recessed fixtures (older designs not rated for insulation contact) cannot have spray foam against them; Cincinnati installers either upgrade the fixtures to IC-rated or maintain the required clearance gap. The thermal-barrier and ignition-barrier requirements for the foam still apply in spaces with electrical work. Practical Cincinnati guidance. (1) Have the foam installer coordinate with any active electrical work on the home. Foam should be installed after final electrical inspection so the inspector can verify junction-box accessibility and circuit ampacity. (2) Identify any pre-IC recessed fixtures before quoting; upgrading to IC-rated runs $30-$80 per fixture. (3) Maintain junction-box access; the foam should encapsulate the cavity but not the box itself. (4) Knob-and-tube wiring (still present in pre-1950 Cincinnati homes) is incompatible with insulation contact; knob-and-tube must be replaced before insulation goes in. Cincinnati pre-1950 housing context. Knob-and-tube wiring in Hyde Park, Norwood, Mariemont, and similar pre-war homes was the standard residential wiring through about 1940. Insurance underwriters generally require knob-and-tube replacement before insulation is added; this is a substantial cost ($5,000-$15,000 for whole-home rewire) that should be factored into any foam project planning for older homes. Modern Cincinnati homes (post-1955) typically have NM-B wiring throughout and the electrical-compatibility considerations are minor.