Listen to the Kapitan,don't need to self- level when yor'e an experienced float.Run up and down lenghts of cable,cable is thinner than depth of notch.I have fitted warm up for 10-12 yrs,before we needed electricians,after all if you can wire a plug! now you need part 'P' qual to wire into t-stat.Fair enough rules are rules,so remember that cable runs back to itself (dual cable)DWS.Run it out and finish it at end,strip wire and put plug on to test with 5 amp fuse.Job done.If anyone needs more advice and more detail on request I'll open a new techno thread on this subject GAZ