Ok, I was just doing some plumbing repairs, and was getting confused over the pipe sizes installed. I think the source of the confusion is that some pipes are referenced by inside diameter, and others, by outside. Why it isn't more universal, I don't know.
anyway, I took off a flared connection to my shower valve, so I could bring it to the hardware store and get a positive identification. Ok: its 3/8ths od copper. great. It just seems odd, though, by today's standards...aren't most faucets 1/2"fip? I'm thinking of a future re-do of the plumbing...most common it seems today to use the stainless flex-connectors for faucet risers, and they're all 1/2".
anyway, the connection on this shower faucet is 3/8 on the inside...but also threaded on the outside, but its way bigger than 1/2". I didn't see anythhing in the store that looked like it would adapt to 1/2". nor did they have a 3/8 to 1/2. Was this a typical size in the old daze?
Oh, yeah, almost forgot: and why did they use a different sized pipe for the hot water side? not the faucet risers...but the rest of the run from the water heater...its 3/8 ID. I see they have pex in that size...but in most retrofits I see here, it looks like people are using 1/2" for both the hot and cold sides.