Why wood is a special case
In a concrete or brick building a cable fault usually stays inside the wall. In a wooden house the wall itself is fuel, so wiring rules for combustible buildings are stricter in three ways.
The three extra requirements
- AFDD protection. Arc faults are the classic cause of wooden-house fires — see What is an AFDD.
- Fire-rated cable. Flame-retardant, low-smoke insulation that does not propagate fire along the run.
- Metal enclosure and protected routing. The panel goes into a metal enclosure; cables run surface-mounted or in metal conduit, not buried invisibly in combustible walls.
What PlanMyPanel does
Choosing a wooden house in the wizard switches these rules on: the generator adds AFDDs, specifies fire-rated cable and a metal enclosure, and the rule engine reports errors if you remove them.