Replacing old shower arm with 1/2"

Old 12-03-22, 01:42 PM
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Question Replacing old shower arm with 1/2"

The shower arm in my upstairs bathroom was probably installed when the house was built, in 1926. It's too small in diameter to fit a modern 1/2" shower head, so I need a new larger shower arm installed. I'd like to get an idea of how this can be done, if anyone here knows.
Old 12-03-22, 01:46 PM
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Probably cast iron plumbing, could open an area in the wall and change the fittings. Not a lot of detail to work with!
Old 12-03-22, 04:15 PM
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I've never seen any other size other than 1/2" used.
1/2" NPT (national pipe thread) is 1/2" internal diameter and roughly just over 3/4" outside diameter.
Old 12-03-22, 09:32 PM
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Yeah I've run into 3/8" pipe once or twice.

No way to change your elbow without opening up the wall on one side or the other. And you might find more small pipe and need to use a galvanized 3/8 x 1/2 reducing elbow.
Old 12-04-22, 02:41 PM
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Have you considered keeping the shower arm as is and just adapting it to a modern 1/2" pipe? Something like this:

I wouldn't necessarily want to start replacing pieces in something that's obviously that old since you may end up having to replace way more than you want to.
Old 12-04-22, 04:16 PM
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Thanks everyone who replied. The plumber opened up the wall enough to see, and said that because the pipe up to the shower arm was an old fashioned type - with a ball joint or something? - if I wanted a 1/2" shower arm, he'd have to run new pipe all the way up from the basement. Thanks Zorfdt for the suggestion, the plumber used a fitting like that instead.


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