An electric storage hot water tank runs on 240 volts. It will be wired with #10 wire, can I use 10-2/ground or do I need to use 10-3/ground. Should I use a 2-pole 30 amp. breaker, 2-pole 25 amp. breaker or a 2-pole 20 amp. breaker. The individal heating elements are rated for 4500 watts and only one turn on a time. Thanks.