Sure, your bow is powerful enough for clean kills on whitetails out to any reasonable distance. However, a 30 yard shot is a long way to shoot at a deer, no matter how accurate you are. The problem, like Macbow alluded to, is that at that distance, it's very easy for a deer to move enough to put your arrow out of the kill zone. Even a casual step will do it. I'm not saying don't do it, because the situation might be perfect for it, but don't expect it to be taking a shot at every deer that comes within 30 yards of you.
I noticed that in an earlier post, you said your 20 yard groups were the size of a pie plate. Based on that alone, I'd say you should restrict yourself to 15-18 yards. However, if you really want to know what your effective range is, just do a test.
Take one arrow, one with a judo point works well, and a notepad and go for a walk in the woods. Take a variety of shots, from a lot of different distances and body positions. Only step off the distances after you take the shot. On your notepad, record your distances and your result. Count a shot a hit only if it is within a feather's length of your intended target. If it's not, it's a miss. Be honest with yourself.
I'd recommend doing several sessions like this and try to take a couple dozen shots. Be sure to wear your hunting gear, and take shots from how you will be hunting. Mix it up so you aren't taking the same shot twice. Afterwards, make a chart or graph and compile your results. It will be readily apparent what your actual effective range is. Well, at least your potential effective range.
There are two very important other aspects to consider before you shoot. First is your own calmness level. Your nerves can effect your accuracy greatly. If you are shaking like a leaf, it might be wise to hold off on shooting. Hunting small game can really help with the nerves.
Second is the attitude of the animal. Calm, unaware of you, and broadside is ideal. A green light. Nervous, staring hard and facing at you is a no go. A good rule of thumb is to never shoot at a deer that is looking in your direction, no matter how close.
Remember, most whitetails shot and recovered with traditional bows are shot within 15 yards.