I am trying to install a light fixture in my Toronto condo (newly built) and to my surprise found these wires. I’m pretty sure white is neutral and green is ground. What is current? And what is the other wire for?
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The novice's rule of wiring is "Not all wires in the box were put there just for your project". Lots of wires have lots of jobs to do. They don't all relate to your project. Leave them alone unless you really, really know what you are doing. Otherwise you will break the other jobs.
In particular, if wires are already bundled together, they are not "one for you and a bunch of spares". There are no spares (with rare exception). They are all doing other jobs. You can add to them, but do not separate them.
Green is ground.
White is neutral.
If you want the light to turn on and off with the switch, attach its hot wire to the single wire courteously marked "LIGHT" by the original installer.
If you want something else to happen, attach the lamp's hot wire to the yellow bundle. I suspect that will make the light run 24x7, but I don't actually know.
You should take a multimeter to that before you mess with it for sure.
In Canada, Orange/Brown/Yellow wire in a building indicates a 277V/480V system, so be wary as that's enough voltage to lock you up good. I've seen cases where an exception was obtained to use existing OBY wire for a 120V/208V system, but you may need 277V compatible fixtures.