Puzzled

[Dennis Alwon]

I read this to mean that any box smaller than 2 7/8" x 1 3/4" would follow the exception. The exception states that all conditions must be met.

I have a door jamb box( for a jamb switch) that is 2 5/8" x 1 1/4". I have never seen them in metal. Could this mean that metal door jamb switches are not allowed assuming they all are smaller than 2 7/8" x 1 3/4"

314.29(A)(1) Boxes 1650 cm3 (100 in.3) or Less in Size.

The openings in the building surfaces, if reduced from the outer walls of the box, shall be centered not more than 25 mm (1 in.) from the centerline of the box, and shall not extend beyond the walls of the box. If rectangular, the opening shall be not less than 73 mm (2 7⁄8 in.) by 45 mm (1 3⁄4 in.) in size. If circular, the opening shall not be less than 90 mm (31⁄2 in.) in diameter.
Exception:
Smaller openings in building surfaces that accommodate one or more individual devices shall be permitted if all of the following conditions are met:

• (1)
  The outlet box that supplies the device(s) is nonmetallic.
• (2)
  The branch circuit wiring that supplies each device consists of a separate nonmetallic cable assembly originating outside the box, or individual sets of conductors in a single nonmetallic raceway, all of which originate outside the box. Other than the connections to a single device, these conductors are not spliced in the box or continued to another device, and no other wiring or raceways enter the box.
• (3)
  Each device is capable of removal from the building surface opening without being damaged. If a special tool is required for this purpose, the applicable circuit directory for the device records the location of the tool, together with a product code/QR code for acquiring a replacement if necessary.
• (4)
  All connections for each device to the branch circuit wiring are made with listed clamping-type wire connectors, which are supplied with the devices. The branch-circuit conductors are arranged to permit the connector(s) to be exposed after the device has been fully removed.
• (5)
  The device assemblies are listed for this application.

 

[letgomywago]

I thought this was for those wierd system 22 receptacles. I think those jamb switches aren't listed as just a box too they're like a mobile home switch even though there's a small box on it.

Some lights have smaller metal boxes than these dimensions too and get a way with it since it's listed.

 

[Dennis Alwon]

I thought this was for those wierd system 22 receptacles. I think those jamb switches aren't listed as just a box too they're like a mobile home switch even though there's a small box on it.

Some lights have smaller metal boxes than these dimensions too and get a way with it since it's listed.

It states it must be listed in item 5 but all must be met and #1 is my question

 

[Dennis Alwon]

I thought this was for those wierd system 22 receptacles. I think those jamb switches aren't listed as just a box too they're like a mobile home switch even though there's a small box on it.

Some lights have smaller metal boxes than these dimensions too and get a way with it since it's listed.

You may be right and I am reading it incorrectly. I don't know

 

[don_resqcapt19]

This only applies where the opening in the building surface, or in your case the door jam, is smaller than the opening in the box. It was added for the purpose mentioned in post 2.
Is the opening it the door jam smaller than the actual box opening?

 

[Dennis Alwon]

This only applies where the opening in the building surface, or in your case the door jam, is smaller than the opening in the box. It was added for the purpose mentioned in post 2.
Is the opening it the door jam smaller than the actual box opening?

Thanks, no the opening is the same but I thought the exception excluded the premise in the first section.

 

[don_resqcapt19]

Thanks, no the opening is the same but I thought the exception excluded the premise in the first section.

The openings in the building surfaces, if reduced from the outer walls of the box...

For your application you stop reading after the above as it does not apply to your installation.

 

[Elect117]

This was a TIA, and might not be enforced in your jurisdiction. Since it might not be in the print or legally adopted copy of the code.


It was kept for the 2026 though.

 

[wwhitney]

For your application you stop reading after the above as it does not apply to your installation.

From a purely grammatical point of view, it is not obvious to me that the phrase "if reduced from the outer walls of the box," which is in the middle of the first sentence, actually has a scope that extends beyond that first sentence. The second and third sentences should really start with "in such cases" or the like if the intent is to limit their applicability to the situation described in the first sentence.

Cheers, Wayne

 

[Elect117]

From a purely grammatical point of view, it is not obvious to me that the phrase "if reduced from the outer walls of the box," which is in the middle of the first sentence, actually has a scope that extends beyond that first sentence. The second and third sentences should really start with "in such cases" or the like if the intent is to limit their applicability to the situation described in the first sentence.

Cheers, Wayne

If there was time I would say we could submit something to get the language cleared up in the 2026.

 

[don_resqcapt19]

If there was time I would say we could submit something to get the language cleared up in the 2026.

Way too late for that...but the submissions for the 2029 code will close in September of 2026 and open shortly after the code is published.

 

[jim dungar]

I read this to mean that any box smaller than 2 7/8" x 1 3/4" would follow the exception. The exception states that all conditions must be met.

I have a door jamb box( for a jamb switch) that is 2 5/8" x 1 1/4". I have never seen them in metal. Could this mean that metal door jamb switches are not allowed assuming they all are smaller than 2 7/8" x 1 3/4"

I read this section as governing the building opening only if it is smaller than the box.

If the jamb opening is the same physical size as the door switch box this NEC section does not apply.

 

[Dennis Alwon]

I am glad to see that others thought the wording was not great.