I installed a new tub fixture. It is the two handle type with 1/2 inch copper going up to the shower and 1/2 copper going down and over to the tub spout. When I run the tub, water drips out of the shower. What might be the problem?
When you say you ran the tub spout down and over are you saying it's not just under the valve? If so this may be your problem. If you have to many fittings between the valve and the spout the added restriction is forcing some water to the shower head.
The side toward the shower is a reduced size, forcing water to the tub first.
If the valve is upsidedown, then some water will be forced up to the shower head.
Some valves don't want you to use both outputs...they want a twin-el if you need both, then cap the other valve outlet. What does the instruction sheet say? Does it say you can use both?
Those valves do not have the shower restrictor and are usually thermostatic valves, such a Grohe. But if they were installed improperly, it would be a "gush/flood" from the shower head, not a drip.