Civil Engineering Reference
In-Depth Information
12
Electrical installations
Electrical cables can be installed into a straw bale wall by direct insertion into the straw
or by fitting conduits into the bales into which the electrical cable is installed. When
installing the cable directly into the straw bale it is essential that the cable be inserted well
into the bale to prevent possible damage to the cable in the future. The strings on the
bales are approximately 120 mm from the face of the bale. When fitting the cable directly
into the bales, insert the cable a minimum of 75 mm into the bale. The render applied to
the face of the bale will be a minimum of 20 mm thick but more likely at least 35 mm.
This will mean the cable will be 95-110 mm below the final surface of the wall. The
major cause of damage to electrical cables will come from hammering nails into the wall.
It would be unlikely that anyone would hammer a 75 mm nail into a rendered wall, but if
it were to occur even this would not cause any damage as the cabling is set into the wall
beyond the nail's reach.
Inserting electrical cables into a straw bale wall
Bales of straw have one face with cut straw and the opposite with bent straw that has a
fluffy appearance. When laid correctly every second row of bales will have a cut face and
every other row will have a fluffy face. It is not too difficult to force the cable into the cut
face of the bale, however the bent straw of the fluffy face resists the installation of the
cable. Consequently it is necessary to cut the face of the bales into which the cable or
conduit can be fitted. Remember that the strings of the bale are about 120 mm into the
bale, so keep your cut less than 100 mm deep to avoid cutting the strings. If you do
accidentally cut a string in the middle of the wall it is not a problem, however, if you cut
multiple strings down the line of the cable it will weaken the wall. If there are heavy
winds following the cutting of strings the wall may collapse.
