[ahalbert]

is it ok to branch off a light on a 20 amp circuit, and if so, must 12 gauge be used to the switch and light?

 

[Jim Port]

What does the circuit serve? Some circuits have restrictions on what they can serve.

 

[rjniles]

And if you are in Canada you can not put lighting on a 20 amp circuit.

Another reason to add your location; you get better answers.