My question is this. You have 4 dwelling units separated by 1-hour firewalls. Can the Feeder conductors to each unit be run thru the attic spaces, or must they be run outside the building as defined by 230.6?
One thing to keep in mind fire walls and fire separation though they are similar are not the same thing.
Fire walls are complete separation usually clear to the roof deck. Fire walls do not have penetrations through them. You do not see openings in fire walls. Like any other code there will always be some exception to the rule.
In your situation I think I would have expected to see a two hour separation if these where separate buildings.
Because you said one hour fire separation I lean more to a single building. But you did not mention if the building had fire sprinklers. Eather way your building official needs to define the structure for you. After it is defined apply the NEC rules if they are defined as separate buildings take that approach from the NEC.
One building cannot be supplied through another. Of course there are always exceptions to the general rule.
If this is one building than yes feeders can supply different dwelling units passing through the attic space of the building.
If however the building code officials define the dwelling units as separate buildings than no you can’t pass through. Each building would have to have a separate service or a single feeder supplying each building.
Town houses are complicated usually they have separate established right- aways for each dwelling and each dwelling unit its self is defined as a building. Separate occupancy permits for each. Each owner has the right to sale the dwelling and transfer the deed to a new owner just like any other single family dwelling. But this is not always the case.
