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Detecting AC current ON/OFF

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I have a project where I need to have a isolated detector to distinguish ON/OFF state (with a detection current of 10mA) in a 10A/230VAC 50Hz circuit. The isolated part makes it much harder of course.
It interfaces with a Atttiny with 12b ADC and analog comparator.

My option list:

- ALLEGRO CT110 Hall Sensor, consumes 1mA at 3.3V, even at the scale of +-5A the difference from 0 to 10mA is only about 3mV.
- Shunt resistor + isolated amp-op - More complex than hall sensor, consumes more energy
- Shunt resistor + optocoupler - impossible to achieve dynamic range required (10mA to 10A)
- CT + some passives - lowest power consumption, more board space

Am I forgeting something? Is there anything specific to this just ON/OFF detection application?

I had a similar problem detecting when the OFF Peak supply was available (for some specific reasons detecting voltage wouldn't work), I used a mains capacitor as a load and a CT with a load resistor, you can adjust the load resistor to set your sensitivity level quite easily, it has been very reliable, switching every day.

Because only detection is required, you can let the CT core saturate at as low as double your threshold current.  This considerably reduces the core size and thus board area required, and also the secondary current that you have to clamp when 10A is passing through the primary wire.

To start a device when another one was switched on I put two diodes in antiparallel and a transformer followed by a full bridge, capacitor and relay.

I use these. works ok, but the power resistor gets quite hot


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