1970s house with a basement finished with tongue and groove boards on the walls. I am wanting to replace all of the switches and outlets but have a question. The electric boxes aren't the typical plastic or metal I see but are a thicker brown fibrous looking box? I am unfamiliar with this type and was wondering if there are any additional considerations or if I just treat them like a standard plastic box?
Those get treated the same as the plastic boxes of today. The problem is that the screw holes strip out very easily and if you miss the nail when attaching them to studs they shatter. They are fiberglass.
Typically they seem to be smaller capacity than some of todays boxes.
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.