I'd like to hijack this thread ....
Let's use the OP's example .... Nu-heat is installed, you have a lovely log of your megger readings at every step, and everyone's happy. Several months go by, and the floor faults, or fails to work. You get the call-back, dig out your Greenlee 2011, and point to a spot on the floor and say 'here is wherre the fault is.'
For the sake of this example, let's also say the fault is in a place where it's pretty easy to identify the cause - say, that new cabinet.
The repair is going to require the cabinet be removed, the floor torn up, essentially a complete bathroom remodel .... because the mats are not repairable. The trace line might be, but the manufacturer, in his installation instructions, makes it pretty plain that a repair is not usually possible.
Someone's going to have to pay for your troubleshooting, the demolition, and the repair. I don't see the cabinet guy being very eager to foot this bill.
Where does that leave us? Do we ask the homeowner to pay for it all, and let him try to collect from the cabinet guy? Do we raise our rates, contingent on getting paid after the homeowner collects? Do we try to work something out with the tile guy? Do we piggyback our bill on the homeowners' lawsuit? Do we go after the cabinet guys' bond?
Your thoughts, please.