I have just moved into a property and want 5 lever mortice locks on the external door. There are 2 locks currently on it and I don't want to replcae if they are already 5 lever , so....How can I tell if I have 3 or 5 lever mortice locks already?
If the property is new to you then change the locks anyway. You have know no idea who the last resident gave keys too. They could have given a set of keys to the mad axeman who lives up the road !
Replace the locks with a quality five lever lock that meet BS6321:2007.
The notches do not correlate directly to the number of levers in the lock.
On a two lever lock the notches (lifts) would be five. Two lifting the levers and one throwing the bolt. The extra two are needed because the key needs to enter the lock case from two sides. Thus the key for a normal mortice lock will be reversible as opposed to say a safe key that only needs to enter from one side.