Paul,
>Thanks for sending the plans. We'll now inundate you with about a hundred questions!

I'll try my best to answer them correctly.

>I see that you have a washing machine and dryer in the bathroom (I don't know any Flemish, so I'm guessing that's what Wasmach and Droogkast are on circuits K and L). Is this a common location?

Yes, it is fairly common especially in flats. Every circuit in bathrooms are obliged to be on a GFI 30mA.

>All your branch breakers (except cct. N) are marked as 2-pole. Is it normal to open the neutral on branch ciruits there now? I heard that this is now the norm in France.

Yes, it is not only normal, but it's required by our code that ALL breakers cut the Neutral as well. The reason being that we have here still older systems which are 110/220V where the neutral is not used. We are therefore working with 2 fases per circuit and no neutral. So as not to differentiate between the different systems our code made a general regulation that all breakers cut the 2 poles. Another reason can be b/c we can still get electric shocks with the neutral here, since our N is only grounded in the scondry part of the transfo and not all along the way as in Britain. The reason being, that we are working with a TT system. We can therefore have a big enough impendancy between the neutral and the earth to eventually get a electrical shock.

>The bathroom water heater appears to be the only 3-phase load, and from the 4 x 2.5mm designation on the cable and the 3-pole MCB, I take it that this has delta-connected 380V elements. Correct?

Yes, correct, (400V) but it's not always the case. Actually normally our boilers are on 230V. This one is an exception.

>It seems that your PoCo really wants a lot of details before they'll connect.

Well, this is not for our PoCo that we do this. This is required by our code and we have a independat inspector who comes to controll the installation. The PoCo is not allowed according to our code to connect without the seal of the independant Inspoection firm.

>One other point I noticed though: The diagram gives full details of which outlets are on which branch circuits, but there's no indication of which phase serves each circuit. Are they not too bothered about balancing the load, or is that the one thing they leave to the discretion of the electrician?

True, our diagrams don't take this into account. The PoCo, however does mind and that's why the PoCo gives only a phase and a neutral per residency in new installations, so that they give number 1 phase and N to to the first residency. the next residency gets number 2 and N and so on. Like this it is equally balanced. It is possible to get 3P and N for one residency only after you have a reasonable explanation and at additional costs. Then, yes, the balancing is left to the discretion of the electrician.