Electrical Layout in a Monolithic Dome

Now that you know some electrical code basics, it is time to plan out what electrical lines that go through the walls of your dome shell. Basically, you only have one shot at getting this right, so plan it well and don’t make mistakes!!!

When we made our first dome, we used smurf tubing because it is very easy to work with. NOTE: This blue, flexible tubing doesn’t fit normal blue plastic boxes. It either needs plastic boxes specially made for smurf tubing, or you can fit it into metal boxes. We used 1/2″ smurf tubing.

If you wish, you can use regular gray electrical conduit in metal or plastic, but unless you have a bender of some sort, you are just going to get yourself in trouble.

After the foam has been sprayed on the inside of the balloon, all the walls, floors and windows have to be marked, and the electrical boxes for lights and receptacles has to be screwed into the foam. If you use metal boxes, make sure you put a ground screw into each box. Then, you have to plan out the run for every circuit on paper. You have to know exactly where the wires are coming from, and going to, and that every box has power to it.

We made the dome with a 3′ crawlspace, so all the wires were coming from under the floors, and then going up the walls. Make sure you connect the switch boxes by the exterior doors with smurf tubing that goes to the outside lights, and don’t forget your outside receptacles!

Once you are done putting all the boxes and smurf tubes on your wall, you need the inspector to have a look at it, even though you have to pay for an extra inspection. He won’t like the fact that you haven’t pulled your wires through, but if you explain that the concrete will mess up the wires, and that you just want him to see what is in the walls before you shoot the concrete, he’ll probably reluctantly agree. So this is not a rough in inspection – it is a pre-rough in. Keep your drawings and electrical plans handy, so he can go over it in detail – you’ll most likely be glad you did.

After the domeshell is finished and the other walls are in place, you’ll be happy if you invest in a good fishing tape. Pushing wire through the smurf tubing is a nightmare without one.
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This entry was posted on Thursday, March 19th, 2009 at 10:31 am and is filed under Monolithic Dome Planning Tips. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.