Library › Home & kitchen › Household ·

US PVC device boxes (Carlon, Allied Moulded): size, cubic inches, device screw spacing

What are the dimensions and device screw spacing of a US single gang, two gang or old work electrical box? · Standard part · basis: Maker catalog data (ABB Carlon, Allied Moulded) and Arrow Hart wallplate catalog; only printed numbers

Also called: single gang box dimensions, old work box cutout size, carlon b120r dimensions, carlon b114r dimensions, 2 gang box dimensions, 3 gang box dimensions, electrical box screw spacing, outlet box 3-9/32 screw spacing, box extender dimensions, smart switch adapter plate, switch box depth, old work box stl

Exact dimensions. True size, with no printing tolerance added.

length: 108.7 mm
width: 25.4 mm
height: 2.0 mm

Notes

US nonmetallic (PVC / fibreglass) device boxes, new work and old work: the sizes the makers print, the cubic-inch capacity as marked on the box, and the one position that every device box shares: the device mounting screws, 3-9/32 in apart.
Sizes are length x width x depth as the maker's catalog data prints them. The data does not say whether an old work box length includes its ears or swing clamps, and two-gang boxes are listed with the long side in different columns, so measure your own box before you cut a wall or print a spacer.
No drywall cutout is published as a number. Allied says to use its template (1/16 in clearance round the box) or to trace the box; Xem does not guess a cutout from the listed outline.
The three template files carry what is printed: #6-32 device screw holes (0.138 in major diameter) 3-9/32 in apart at a 46.0 mm gang pitch. They are a design aid for a spacer, extender or smart-switch adapter plate, not a box: box interior, wall thickness and radii are not printed.
Box fill: the cubic inches are as marked by the maker (NEC 314.16 sets the fill rules; this page does not restate them).

US PVC device boxes (Carlon, Allied Moulded): size, cubic inches… size chart

parameter	value
Carlon B114R-UPC old work, 1-gang	14 cu in; 4-1/8 x 2-1/4 x 2-3/4 in (L x W x D)
Carlon B120R old work, 1-gang	20 cu in; 4-1/8 x 2-15/16 x 3-5/8 in
Carlon B225R-UPC old work, 2-gang	25 cu in; 3-15/16 x 3-1/8 x 2-3/4 in
Carlon BH234R old work, 2-gang	34 cu in; 4.3 x 4.36 x 3.59 in
Carlon B355R old work, 3-gang	55 cu in; 5.72 x 2.79 x 3.69 in
Carlon B232BR new work, 2-gang	32 cu in; 3-3/4 x 4 x 3 in
Allied Moulded 9312-E series old work, 2-gang	28.0 cu in; depth 2-3/4, width 4-1/8, height 3-1/4 in
Allied Moulded 9329-EW series old work, 2-gang	32.5 cu in; depth 3-1/4, width 4-1/8, height 3-1/4 in
Allied Moulded 9363-EWK old work, 1-gang	16 cu in; 2-3/8 x 3-1/4 x 2-7/8 in (width x height x depth)
device mounting screws (all gangs)	3-9/32 in (83.3 mm) apart, one pair per device; #6-32 machine screws
gang pitch (device centre to centre)	46.0 mm (1.81 in), from the wall plate catalog
Allied old work cutout rule	template 1TP (1-gang) or 2TP (2-gang) leaves 1/16 in clearance round the box; or trace the box, stopping at the ears
Allied old work ear screws	two #8 sheet metal screws, at least 3/4 in long, one at each end of the box
wall thickness, radii, ear and clamp positions, cutout sizes	not printed as numbers: not modelled

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

ABB (Carlon)	B120R 1-gang old work box, catalog data (4-1/8 x 2-15/16 x 3-5/8 in, 20 cu in)	web	Publisher's page; dimensions are facts
G.T. Sanders (ABB Carlon data)	B114R-UPC old work box (14 cu in, 4-1/8 x 2-1/4 x 2-3/4 in)	web	Publisher's page; dimensions are facts
Stoneway Electric (ABB Carlon data)	B225R-UPC old work box (25 cu in, 3-15/16 x 3-1/8 x 2-3/4 in)	web	Publisher's page; dimensions are facts
Stoneway Electric (ABB Carlon data)	BH234R old work box (34 cu in, 4.3 x 4.36 x 3.59 in)	web	Publisher's page; dimensions are facts
Crescent Electric (ABB Carlon data)	B355R 3-gang old work box (55 cu in, 5.72 x 2.79 x 3.69 in)	web	Publisher's page; dimensions are facts
Stoneway Electric (ABB Carlon data)	B232BR new work 2-gang box (32 cu in, 3-3/4 x 4 x 3 in)	web	Publisher's page; dimensions are facts
Allied Moulded (via Elliott Electric)	Old work box catalog sheet 9312/9329 series: cubic inches, depths, cutout rule (box plus 1/16 in), screws	web	Publisher's page; dimensions are facts
Stoneway Electric (Allied Moulded data)	9363-EWK old work box (16 cu in, 2-3/8 x 3-1/4 x 2-7/8 in)	web	Publisher's page; dimensions are facts
Arrow Hart / Hubbell Wiring (via Elliott Electric)	Wallplate Dimensional Information, catalog pages J-2 and J-3 (gang pitch 46.0 mm, strap spacing 83.3 mm)	web	Publisher's page; dimensions are facts

Xem scan

File coming

No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.

Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=device-boxes-us

Schematic, not to scale.