Another common question I encounter (just asked now in fact) is how to use the CFTBN fused terminal block in an application with more than one live terminal. The example recently was an emergency lighting application. The engineer had a live and a switched live connection. The standard CFTBN has only one fused pole.
The answer lies in the interlock. One the fused end of the CFTBN is an interlock or dovetail. Using this a 1-pole CFTBN can be attached. As the 1-pole is fused, this provides an additional fused pole.
CFTBNs with more than one pole only have an interlock on the fuse end. It is not possible to interlock anything to the other end. Instead you should look at the CFTBN/4 or /5.
For three-phase power supplies, interlock three CFTBN/1s to create fused poles to each phase.