I don't know what the code is in your area but with only 8amps it should be fine. if it's cheap it would not hurt to run more then one, for possible future use. i'll run 2#10 for A/C's running on 220v 20 amps, it all depends on the how long it is and amps really. here's a good calculator
http://www.jhlarson.com/ind_tables/volt/calc_wiresize.htmAnd on the safety side, VOLTS don't kill, AMPS do. you can get a sapped with 10,000 VOLT , like in a tazer and be fine but get zapped with 30V but only 0.5AMPs and your done. now it's not to say volt doesn't play it's part but it just pushs amps trough you, the less resistance in you (IE: being wet, grounded, very high salt diet, ect) the easier it is. it takes something like 0.70mA to stop your hart.
sorry, they drive safty into us at work