- Replacement of two Smoke detectors. Replacement will be changing from smoke to carbon dual function detectors Reason for today’s visit with the customer was replacement of two smoke detectors. Upon arrival I investigated the smoke detectors and discovered they were original to the home in 1963. They were still some how functioning and going off. Talking with the customer he informed me that throughout the home the rest of the detectors were battery stick ups that his son had put up. I recommended hardwiring all of them to make them interconnected. This would include installing three new smoke detectors by attic access. At this time customer requested to replace only the two old ones with new detectors. These detectors I replaced with Carbon/Smoke detectors to meet current safety standards. At this time all work has been completed.