The electrical rough-in for our healthy house was started after
the roof was on enough to protect the wiring from getting wet.
The first step was to install electrical boxes for the following:
- Outlets
- Switches
- Telephone
- Cable TV
- Computer network
- Doorbells
- Smoke alarms
- Surface-mounted ceiling lights
Electrical boxes are usually a major source of air leakage
in typical homes. To keep everything air tight, we used special
air tight electrical boxes made by Nutech Plastics. These have
one gasket around the edge that contacts the drywall, and another
around the area where the wires enter the box. A small hole is
cut in the second gasket to allow the wire to be inserted into
the box. Then the hole is sealed with 100% silicone caulk to keep
it air tight.
Although surface-mounted fixtures normally use a standard electrical
box, "can" type down-lighting does not. We used a really great
air tight can-type down-light from Juno
Lighting that solved this problem. The following picture shows
one of the lights installed in the ceiling.
I originally wanted to run all of the house wiring in conduit.
Several companies make armored cable (a type of "pre-fab"
conduit), which is sometimes used in commercial applications.
Most of that cable isn't air tight, though. A few companies do
make an air tight version of armored cable, but it is pretty costly.
There are two reasons why conduit is a good idea. First, it protects
the wire from catching fire, and it prevents fire from spreading
along the wires. Conduit also keeps the (strong) smell of the
wire from getting into the house. It would have cost about $5,000
to run all wiring in regular conduit. We decided we could save
a little money by using standard romex instead. What we did was
to buy the wire well in advance of installing it, to let it off-gas
as much as possible. It turns out that the insulation material
that we used inside the exterior walls and in the attic is fire
proof. Because it was sprayed on in a semi-solid form, it surrounded
the wire and provides a degree of fire protection. Finally, we
are using foil-backed drywall to help keep any residual wire odor
(and other odors from outside) from entering the house. Without
foil backing, drywall is slightly permeable, and it is possible
that a strong odor could seep through the material, especially
over a period of months or years.
To keep the romex from getting damaged, it is run through red
plastic rings that sit inside holes in the steel studs. Our main
interior junction boxes are shown in the photo below.
To help minimize exposure to electromagnetic fields (EMF),
wire in the bedrooms was run only vertically where possible. Long
horizontal runs would have made it difficult to avoid being next
to the wires and their associated EMF. There is some evidence
in the scientific literature that EMFs can cause or aggrevate
immune system disorders, so it made sense to limit our exposure
where possible.
We did something a little different with the telephone and
cable TV wires. Instead of connecting each outlet to every other
outlet, such as is done in most homes, a single wire was run from
each outlet to a central electrical room. This gives us maximum
flexibility. It would allow us to install a fancy video system
later on, or a central telephone system with an extension for
each phone, for example. We also ran wires from the doorbells,
doorbell switches, outdoor sprinklers and ventilation controls
back to the electrical room for tie-in to a future home automation
system. Part of the wiring in the central electrical room is shown
below.
Ventilation System
Here's a picture of the ductwork for our ventilation system.
The ducts are bare aluminum, and are run through the attic space. They couldn't
be run under the house, since it was built on a foundation. Bare aluminum
was used to avoid the fiberglass insulation that commonly surrounds ducts.
The ducts were insulated instead with an aluminized bubble wrap (not shown
here).
The air handler and filter for the house is shown below. The
filter uses a 3HP motor. It contains about 500 pounds of activated carbon,
along with pre-filters and a final HEPA filter stage, so that it removes
dust/pollen/mold, as well as chemical pollutants. Unfortunately, the filter
ended up costing about $500/month (for electrical alone) to operate. The
photo below was taken before the air conditioner was installed (it sits
on the concrete pad, to the right of the stainless steel filter box). This
picture was also taken before the filter was hooked up to the house. There
are ducts running from each end of the filter, up to the two square connection
points that can be seen just above the filter.
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