Thanks for your response, I noticed in my parents new home it is wired with 10 is that OK? Dangerous? Please also see my other posts on the lights dimming when the AC comes on could this be the cause?
If this is for the A/C unit, there are special rules that apply to the wire size and over current protection. As stars said it depends on the connected load, and also on the information on the A/c unit lable.
I am closing this thread from further discussion because the correct response has been given and further discussion should be between the home owner and his electrician.