You can wait till you have built your cob house to install your electric pipes. This gives you a bit more freedom to place them once you have more of a feel for the room, but it means cutting out channels of rock hard cob, which is not easy, and then re-cobbing over them to hide them back in the wall.
So this time here at Eco Caminhos we decided to build the pipes in to the wall as we built up. This means no more cutting in to hard cob, and all we had to do was make the electric plan in advance. When the house is built and the electricity sucessfully fitted I will be able to say for sure that this system works, but until then, this is a trial run.
The only obstacle I can foresee is that the pipes get crushed by the cob, but I think ours is drying quick enough that there will not be enough weight of wet cob on top of the pipe at any one time so unless we break through a pipe whilst integrating layers of cob then all should be fine.
So get your electrical plan and build up your walls to about the level of your plug sockets. Your pipes will run around the walls at the same height as the outlets so its best just to stick to this height
Lay all your pipes and secure down with rocks or wire. If you have an lights in the higher parts of the wall you can hold them in place with stakes like this. You can cob around the stakes and leave them in the wall for good. Just make sure the tubes or stakes dont run too close to the wall as you may affect the structural integrity.
As you build up and around the pipes, make sure to leave a bit of space to move the pipes in to place for when you come to fit your outlet housing. It is probably best to chisel the space for the housing out of the wall when you are ready rather than trying to fit it now. If you do fit it now though remember to have it sitting out of the wall a bit as you are still likely to have a few centimetres of finishes go over the cob which will end up leaving the outlet box sitting inside the wall and difficult to attach a face.
Remember to leave space to run your pipes under the windows if these are below or above your electricity level.
When your house is ready then you can run all your cables from box to box and get your house electrically charged.