For the benefit of other folks who follow these topics the EZSwitch30 is rated at 240v 30 amps inductive load, per the online specs. From the discussion on the Smarthome forum about the OutletLinc it looks like they derated a 16 amp relay to 4 amps (480 watts) for an incandescent load. Lights bulbs are a resistance load but have a much higher current draw initially when the filaments are cold. I googled the topic of resistance versus inductive load and they all say about the same thing. There are inductive loads (like pump motors) and resistance loads with incandescent lights a special case resistance load due to the varying resistance of a cold filament versus a hot filament. A relay is derated some percentage from it resistance load rating when handling an inductive load such as a pump motor and derated even further for incandescent lighting. Applying the same strategy to the relays in the EZSwitch30, derating a 30 amp relay (which might have a higher resistance load rating since the published specs say 30 amp inductive load) would take a 120v incandescent load to 7.5 amps or 900 watts per relay. In the example that started this discussion I would follow my first suggestion and put the 1000 watt load on one relay and the 600 watt load on the other but also with the previously stated concern for the total amps being drawn from what is assumed to be an outlet on a 15 amp breaker. Taking 1600 watts total, divided by 120v, gives 13.3 amps. If the outlet supplying the EZSwitch30 has anything else on that electrical circuit, it could overload a 15 amp breaker. A more conservative approach would be to supply each EZSwitch30 relay from a separate 120V 15 amp circuit, or a single 120V 20 amp circuit, using the appropriate gauge wire and split the 1600 watt incandescent load equally across the two EZSwitch30 relays.
From the online specs for the EZSwitch30…
Types of loads — Resistive or inductive (lighting, pumps, AC compressors, water heaters, etc.)
Maximum Load Current — 30 Amps @ 240V Inductive