I`m a newbie to this forum and unlike a lot of you guys only a competent DIY`er, but I would welcome help with this one please. I have two mains wired smoke alarms in my house, one up and one downstairs that are now 12 plus years old and I want to "simply" replace them for this reason. The units are "Newey/Newlec" make that are now obsolete and the problem I have is that the mains wired push-fit plug that comes through the ceiling (from a junction box) into the back of the alarm also forms the cover for the back up battery, so it wont fit new units. Do new units such as the BRK ones (S/F 81969) come with a prewired push-fit plug for connection into the junction box or what is the normal routine for replacements? I would be grateful for any help please.