I just bought a home that was built in 1981. My wife and I have gone through the house updating various items. We noticed that our smokealarm was beginig to churp so I thought a new battery! Well I pulled off the cover and foud that the smokealarm was hard wired. The firealarm has a nuclear sysmbol, not sure what to think of that? Anyhow, I bought a new FireX smoke alarm that can be wired and has battery back up. There is only one smoke alarm that is hard wired in the house. Here is the question: The old smoke alarm has 4 wires leading into it: green, black, white, yellow. The new smoke alarm has three wires: white, black, yellow. Yellow is to be used if the the smoke alarm is connected with other smoke alarms. What do I do with the other 2 wires?

I am trying to install a ceiling fan but the junction box is loose on one side. Can I fix it myself?