12/3 UF – metal box… which connector
I have a single 12/3 UF romex (the wide, flat, grey stuff) going into a metal box, where is will junction with a 12/3 yellow romex. My usual romex-box connector clamps go into a 7/8″ dia. knockout. I also have the larger clamps that go into a 1-1/8″ KO. These larger connectors are wide enough to fit the UF but do not actually clamp it, as they are designed for fatter wires (probably #8/3 and larger if I had to guess). What’s the correct connector? Do I actually need one that clamps? I notice electricians using simple open bushings a lot with metal boxes, and they don’t clamp. Wire is stapled within 6″ of box, of course.
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around here a clamp is needed to fasten the cable to a metallic box, I have never used a bushing as you describe, but ...when in Rome, yada,yada,yada
...bushings ARE required with "romex" is when the cable passes through metal members, ..like studs,
no mention in that section of bushings AT the box
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Plastic bushings are definitely accepted here where romex enters a metal box or panel. It simply sleeves the hole to protect the wire from burrs. There is no clamping mechanism.
bushings would be OK if the boxes are in the wall, but a surface mounted panel or box could be a problem with partial openings on the top......
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Are you calling connectors like these "bushings".http://www.aifittings.com/c_9.htm#NM94
http://www.aifittings.com/c_8a.htmThey have a clamping feature.Now there is a specific UF connector. But I thing that they are mainly for use in wet conditions. If you look at the different NM connectors you will see that they list the range of size of cables that they take.If you look at these tables they show it as the different size and number of cables (NM, SE, and flex cables) that a given version will accept.http://www.aifittings.com/c_19.htm
http://www.aifittings.com/c_20.htmBut they never list UF.But I don't see any reason that NM connector would not be acceptable for UF if you pick one based on the size of the cable.
Any cable, be it romex, UF, SE, SO, whatever, needs a connector at every box, be it a metal box, or a plastic one. Many plastic boxes have the 'connector' built into the box, so a separate fitting is not needed. The purpose of the connector is to prevent a 'tug' on the wire to make it to the wire connections; it's there to relieve the strain. It also keeps the wire from rubbing against the sharp edge. There is, first of all, a type of romex connector that has a metal strap, thet clamps down on the wire using two screws. The metal strap has a slight curve to it. The proper clamp for UF is a similar design, but the strap is noticeably 'flatter', and wider across the opening. I have seen these connectors in the box stores. As for the bushings that are simple plastic rings: they are used in alarm and data work, or where wires pass through partitions in enclosures. They provide no strain relief, and are not intended for use where romex, or UF, enter a box.