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What's the proper bushing or coupling for stepping 1" EMT down to 3/4"? Does such a fitting (bushing?) even exist?

My searches for a 1" to 3/4" EMT adapter pretty much come up empty.

Goal: the top of the outdoor box I'm using to house some outlets has a female threaded fitting which works great for 1" EMT, but I'm running 3/4" so I need some kind of step-down.

Are the fittings in the tops of the outdoor boxes regular NPT pipe thread, so a 1" x 3/4" NPT galvanized bushing will work? (Or whatever NPT size the 1" and 3/4" EMT uses).

Box and fittings I was thinking of using

Gary Aitken
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2 Answers2

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You need the correct EMT-hub transition setup in addition to a reducing bushing

While it's true that you'll need a 1" to ¾" threaded reducing bushing (Bridgeport 1163 or equivalent) for this installation, that's not the only piece you need to make this work. You see, the threads on standard EMT connectors are designed to mate to the threads on locknuts, not the somewhat different threads found on the inside of the hub fitting sitting atop your construction power outlet box (cabinet), or on the inside of a reducing bushing for that matter. As a result, an inspector is within their rights to reject your installation if you simply slap a standard watertight (compression) EMT connector in your reducing bushing and call it a day.

Instead, you'll need to use a Bridgeport 291-RTNPT to make the EMT-hub transition work here. If you can't obtain one of those through your local supply house, your local inspector should accept a rig consisting of a EMT-RMC female-female transition fitting (Bridgeport 291-RT or equivalent) and a ¾" RMC nipple threaded into the reducing bushing instead.

ThreePhaseEel
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I think you should search for "reducing bushing". Here's one I found (example only) but it seems to be sold in box quantities only. Why not check with a local or online electrical supply house?

enter image description here

Technically, EMT conduit isn't threaded itself, just via end fittings, while rigid and IMC are/can be directly threaded.

Edit: According to @ThreePhaseEel I was wrong thinking the threading of EMT fittings matches that of rigid/IMC threading. As TPE describes in their answer, there are apparently special fittings to convert EMT ends into female or male rigid pipe threading (which would connect to a threaded hub in a box).

Armand
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