Manufactured airtight light fixture or receptacle

Frame and seal airtight plywood box - Seal wiring penetrations - Seal to air barrier with tape or gaskets as appropriate

Many pot light boxes that claim to be sealed, are not. It is therefore necessary to either seal the outer cabinet or install a poly pan box around the fixture. In either case it is important to maintain the required clearance from the insulation. Fixtures should be IC or non-IC (insulation cover meaning insulation can be in contact) rated. IC rated allows for insulation to be in contact with the fixture, whereas non-IC rated does not allow for insulation to be in contact with the fixture.