metal 4"Sq. box

[Robert Mattison]

The NEC code book 2008 edition.

Can a 4"Sq, x 1-1/2" box extension ring be added to an existing
4"Sq. x 2-1/8" deep box.

When finish, I will be installing a 4"Sq., 2 gang, 1" raise, plaster ring so I
can install two switches inside this box. (note: when finish this box will
be cover with sheetrock, expect, the open front, which is where the
switches will be visible.)

Does the NEC allow or probibit this practice?

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[Jerry Peck]

The NEC code book 2008 edition.

Can a 4"Sq, x 1-1/2" box extension ring be added to an existing
4"Sq. x 2-1/8" deep box.

When finish, I will be installing a 4"Sq., 2 gang, 1" raise, plaster ring so I
can install two switches inside this box. (note: when finish this box will
be cover with sheetrock, expect, the open front, which is where the
switches will be visible.)

Does the NEC allow or probibit this practice?

Robert,

The NEC will not prohibit you from doing that, but the 2x4 studs, which are only 3-1/2" deep, will prohibit you from doing that.

*IF* you have *NO* protrusions out the back side of the box (you likely will have) then the box and extension ring will be 3-5/8" deep ... in a 3-1/2" deep wall ... ... and then the screws out the back of the box ...

[Robert Mattison]

A big thanks, to you Jerry, with your answer.

When I have a problem, its nice to know, that there people like you
involved with this Form, that can quickly supply the answer I needed.

But what I really like about you, is you go to great lengths to supply a detail answer.