Home Postcodes by state NSW 2278 Postcode 2278 2278 is the postcode for 3 localities in NSW: Barnsley, Killingworth and Wakefield. Localities with postcode 2278BarnsleyNSWKillingworthNSWWakefieldNSW Postcode 2278 State or territory New South Wales (NSW) Localities 3 Council area Lake Macquarie Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 2267 · Postcode 2280