Building house in France, wiring it up ourselves to French standards in order to get French sign-off for mains connection. It is understood that the NORMES don't like the use of wiring like ours, i.e. several cores in outer sheath. When the thermostats are connected (there are 6), the obvious way to do it in UK would be to use a 4-core cable Live, Neutral, Switched Live, Earth all contained in a tidy sheath. (The thermostats are chronostats and need power). Question: It's obvious that if the heating control wires are installed before the inspection the guy will have the vapours. But our cabling makes linking the thermostats to the control is pretty trivial, later on. Would it be a good idea to delay the heating wiring until the basic power/lighting circuits are signed off and the house is connected, then use "our" type of cable?