If is is 8:00pm EST it would be 5:00pm in Phoenix
No, if it's 8:00PM EST, it would be 6:00PM MST in Phoenix but 5:00PM PST here where I live.
Now when we go to DST, and it's 9:00PM EDT, it would be still be 6:00PM MST in Phoenix and 6:00PM PDT.
I think :-)