Wiring your panels
You have several choices for your wiring strategies: either integrate a surface-mounted wiring system within a taller and thicker baseboard system, or use the variety of wiring chases pre-cored in the foam at the factory. Most people pick the latter, as material costs will typically be lower.
Drilling through end-plate in a panel in order to run wiring.
The pre-cored wiring chases in the foam typically run horizontally at about 14" and 44" (counter height) off the floor, plus vertically at 4-foot centers. Supplemental chases can be ordered as needed. When using these pre-cored one-inch wiring chases, you can either thread the wiring as you go or install it once the panels are up. Aspects of these three approaches are listed here; during the early stages of this website, each has attracted extensive comments within SIP Talk section. Be sure to check with your particular manufacturer for their special wiring tips.
Regardless of which variation you use, you must plan ahead for your eventual wiring method. In virtually all cases, some wiring must be run during construction. For example, you'll need to install some wiring beside each exterior door, to provide power for exterior lights and interior-mounted switch boxes.
Wiring after panels are up. When using this approach in houses with basements, crawl spaces and second floors, you'll need to pre-drill all bottom plates, lining up your drilled holes with the pre-cored holes in each foam panel as you go. Drill each hole just prior to placement of the next panel. When you're ready to run wire, cut out enough interior facing and foam for each electrical box where it will intersect with a vertical wiring chase. Thread wire up from below the floor, through the hole in the plate, then up and out the electrical box directly above. Wire runs down from one box, over through the floor, then up to the next box. This approach takes more wire and additional time, but doesn't interrupt the framing process very significantly.
If using this approach with slab-on-grade construction, you can run the wiring vertically up through the top plate (if it's pre-drilled), through the ceiling joists and down to the next box.
Threading wiring during panel attachment. This approach adds time during the framing process. While it eliminates the drilling of bottom plates, you do have to remember to drill end plates at corners, cut out facings and foam for electrical box locations as you go (for two wire pigtails to most boxes), cut in holes where wiring will move into a partition wall, and then run and cut all the wiring as you go. But this approach significantly simplifies the electrician's wiring process once panels are up.
Surface-mounted wiring. Winter Panel is one of several manufacturers to recommend running wiring through a built-out baseboard system. Spacers are nailed about 1.5 inches apart at baseboard height and capped with a 16-gauge steel cover. Wiring runs behind it to either thin-profile boxes cut into the baseboard or up through vertical slots cut in the field to standard wall-height boxes. The wiring spacers are then covered with 3-inch baseboard trim. Other baseboard electric systems are available on the market; they come at a price premium.
Other ideas. Some manufacturers will pre-cut electrical boxes at the factory; this would be particularly useful for anyone threading wire during the panel framing stage. Thermocore embeds electrical boxes and 3/4" plastic conduit within their urethane foam panels prior to the foam injection process; this significantly reduces the on-site work required of any electrician working with the product. In a pilot project by the University of Oregon's Center for Housing Innovation, an electrical chase system was created at the rim joist level, accessible from the exterior; they reported this slightly reduced the time required to install wiring in SIP-wall homes, compared to conventional stick framing. Finally, comments in the SIP Talk section point to the need for a flexible wiring system, one that can be updated as products and needs change.
Generic. Remember that you won't be attaching electrical boxes to 2x lumber with nails; most often your electrical boxes will attach to the interior panel facing with a plaster ring. This adds some cost. Before you place the boxes, consider foam-sealing the wiring back into the electrical chase; otherwise, any air leaks from the outside to the electrical chase system can allow air to migrate in electrical chases throughout the panel walls.
Cost comment. An informal survey of builders who normally use SIPs reported that their rough-in wiring costs increase by between 5% and 10% when their electricians are working with SIP exterior walls. Panel fabricator Jim LeRoy recommends that if your electrician is skittish about costs when they're new to SIPs, have him bid on everything but the exterior wall wiring rough-in on a fixed-cost basis; then set up a time-and-materials bid on wiring the exterior walls.
Warning: Most panel manufacturers warn that installing recessed lights in their ceiling SIPs is prohibited. You'll either need to run track lights, surface-mounted lights, or just move your lights to interior walls. And where you plan to hang any heavy objects from the ceiling, such as a ceiling fan, that need should be clearly communicated to the SIP factory so they can pre-install some lumber behind the facings in order to support the fan.