Zone 1 - IP65 (or IPX5)
Light fittings in this zone must be spray-proof. Look for an IP number of IP65 (or IPX5) or higher.
Zone 2 - IP44 (or IPX4)
Light fittings in Zone 2 must be splash-proof. Look for an IP number of IP44 (or IPX4) or higher.
Zone 3 - IP20
There are no special requirements in this zone in the United Kindgom. In Ireland, Zone 3 requires IP rated products.
N.B. These regulations apply to domestic applications only, according to IEE Wiring Regulations (17th Edition), BS 7671: 2008. For non-domestic applications, please refer to your electrician.