Cooking a ham in the crock pot takes around 6 to 8 hours depending on the size of the ham you're cooking.
A good thing to do is place the ham in the crock pot overnight and let it cook let the ham cook in the crock pot while away at work or while doing something else.
The good thing about a crock pot is you can cook the ham for hours without burning it as long as you keep the crock pot full of water so it doesn't dry it out.
The hams internal temperature when fully cooked should be 140 F but you can leave the ham in the crock pot on warm setting to keep it warm and ready to eat.
You can also make great tasting ham in the crock pot by spreading brown sugar mixture all over the ham and place, flat side down, in crock pot.