Don't forget that the OP asked:
<<In Ontario, according to one simplified guide, you can have up to 12
per circuit -- either light outlets or plug outlets, or both. But
after studying the guide, I'm not clear on this:
Does a standard AC wall outlet with two receptacles count as one
or two? >>
It is true. The Canadian Electrical Code allows a maximum of 12
outlets per circuit for 15A lighting and general purpose circuits.
The CEC does not require a dedicated circuit for a wall A/C, but it is
The answer for the OP is that a standard AC wall outlet with two
receptacles counts as one outlet for CEC purposes.
Of course the other comments above are valid. If he's wiring in a new
A/C unit, he should probably run a separate circuit because of the
high current draw. If it is existing wiring, he should be careful
when he is running the A/C not to draw much additional current from
other outlets on the circuit.
There is a small forum on Canadian Electrical Code at
www.selfhelpforums.com at which you might get additional help.
Mr Fixit eh in Belleville, Ontario