Short answer: 4 in [102 mm] of inside depth carries an 8 in [203 mm] panel PC, an E-stop and two pushbuttons, with power and network landing in rear glands. The screen size on the label decides nothing here: the panel's rear projection, plus connector room, plus a wiring loop, sets the number. For a typical panel PC of this size that arithmetic lands on 4.0 in exactly, and a bare touch monitor drops it to 3.5 in [89 mm]. Stock wall-mount boxes start at 6 in [152 mm] deep because they are drawn for backplanes and conduit, so a genuinely shallow station is a custom box. Specify 304 stainless, your depth and a factory-cut face, and it is delivered in 10 business days counted from your approval of the drawing.
The depth budget, layer by layer
Start at the back of the display, because that sets your depth, not the screen diagonal. A typical fanless 8 in panel PC projects 2.0 to 2.2 in [51–56 mm] behind the mounting face with its connectors seated. A bare touch monitor of the same size sits nearer 1.5 in [38 mm]. Behind the projection you owe two layers: 1.0 in [25 mm] where connectors and air live, and 1.0 in [25 mm] of wiring loop, which also swallows the 0.5 in [13 mm] a gland lockring stands proud inside the wall.
| Layer | Depth | What it buys you |
|---|---|---|
| Display rear projection | 2.0 in [51 mm] | panel PC with connectors seated; a monitor-only display is 1.5 in [38 mm] |
| Connector and air gap | 1.0 in [25 mm] | right-angle cord sets seat, air moves off the case |
| Wiring loop and gland tails | 1.0 in [25 mm] | service loop plus lockring depth |
| Inside depth to order | 4.0 in [102 mm] | outside depth runs about 4.4 in [112 mm] with door and back wall |
Worked example, the station above: 2.0 in of panel + 1.0 in of connector room + 1.0 in of loop = 4.0 in [102 mm] inside. Put that figure on the drawing and you carry real margin. Connector style moves the total fastest. A straight VGA or serial plug stands about 1.5 in [38 mm] off the case, so order right-angle or pigtail cords to keep the budget, or ship it with straight plugs and quietly buy yourself a 5 in [127 mm] box.
What pushes the station back to 6 in
Depth creeps back the moment the station takes on panel-room hardware, and every row below is a station you can actually quote:
| Configuration | Inside depth to order |
|---|---|
| Touch monitor, three buttons, glands only | 3.5–4 in [89–102 mm] |
| Panel PC, three buttons, glands only | 4–4.5 in [102–114 mm] |
| Touch monitor with a mini PC on a rear bracket | 6 in [152 mm] |
| Panel plus terminals, duct and conduit bodies | 6–8 in [152–203 mm] |
Conduit is the big one. A 3/4 in rigid 90° ell with its locknut stands about 2.5 in [64 mm] off the back wall, which is why stock boxes open at 6 in [152 mm]: they are drawn to swallow it. Land power and network as sealed cord grips instead — three M12 glands in the rear wall — and that depth is yours to reclaim. Terminals arrive with company. NEC 312.6 sets minimum wire bending space at terminals by conductor size, and the wiring duct that holds the loops wants about 1 in [25 mm] of its own, with NFPA 79 capping duct fill at 50 percent of the cross-section. Keep the station to a display and buttons, and none of that lives inside your box.
The face: cutouts, edges and the E-stop
The display needs a door cutout of about 7.3 × 5.6 in [185 × 142 mm]. Take the final number from the panel drawing: display makers print cutouts with tolerances near ±1.0 mm [±0.039 in], exactly the band a factory laser holds and a hand-held holesaw does not. On a 12 × 10 in [305 × 254 mm] face, that cutout leaves about 2.3 in [58 mm] of steel each side — room for a column of 22.5 mm operator holes, with the E-stop centered 2 in [50 mm] from the display edge so a gloved fist clears the bezel.
Three details keep the face sealed for the life of the station:
- Hold every cutout 1 in [25 mm] or more off the door edge. The gasket land under the perimeter seal needs continuous flat steel, and a hole beneath the gasket is a leak no latch torque fixes. The same flatness logic sits behind gasket compression and cover flatness.
- Fit operators rated IP66 in their own right, with their mounting o-rings installed. The station rating follows the weakest hole in the door, and what NEMA rating a panel keeps after you cut it and mount devices walks that whole chain.
- If you punch a spare 22.5 mm hole for a future button, blank it with a rated cover in the meantime; sourcing NEMA-rated blank covers keeps the face sealed until the day you need it.
The display seals to the door on its own bezel gasket, so clamp it in a star pattern to the torque printed on the panel drawing and the front face is done. The cutout and gland guide carries the hole-sizing fundamentals if you want them next to this.
Heat: the quiet depth driver
A sealed shallow box sheds its heat through its skin, and the skin is small, so run the number before you commit. Take the 12 × 10 in [305 × 254 mm] face at 102 mm of depth: the surface, in inches, is 2 × (12 × 10) + 2 × (12 × 4) + 2 × (10 × 4) = 416 in² [0.27 m²]. In still air, a metal box transfers roughly 0.01 W per in² per °C — polished stainless a little less, so add 20 % to the rise — which gives 416 × 0.01 ≈ 4.2 W per °C. A fanless panel PC dissipating 30 W then rises 30 ÷ 4.2 ≈ 7 °C [13 °F]. At a 35 °C [95 °F] plant the inside sits at 42 °C [108 °F], inside the 50 °C [122 °F] limit most panel PCs carry, with 8 °C in hand.
Double the load and the margin goes. A monitor-plus-mini-PC station at 60 W rises about 14 °C [25 °F] and lands at 49 °C [120 °F], which is your signal to take the 6 in [152 mm] depth or a larger face. CNC control enclosure sizing with wiring and heat runs the same arithmetic at panel-room scale. Outdoors, a dark face in full sun adds 10 °C [18 °F] or more on its own, so put the sun into the sum before you trust the margin.
Which part carries the rating
Most panel-mount displays carry an IP65 rating at the front bezel only, tested with the panel bolted to a flat plate. The rear case, the connectors and any vents carry none, so the display seals the window and the box seals everything else. In the 8 in HMI housing we build, the wording is an IP65-type front seal with the display installed, manufacturer rated, and the station around it is rated NEMA 4X / IP66 by the manufacturer; not UL listed. NEMA writes the type definitions and tests nothing, and if your project insists on a listed box, UL 50E vs NEMA 250: listed or manufacturer-rated lays out that route.
On the specification side, NEC 110.28 says an IP code cannot stand in for an enclosure type rating in US installations, so a spec written as Type 4X needs a Type 4X box. Ten minutes of verifying an HMI NEMA rating claim before the purchase order saves a washdown surprise later. When the wiring behind the panel hangs where hands or hoses reach it, HMI rear wiring protection is the companion build. Open that rear cover only after you lock out the feed and verify absence of voltage at the terminals.
What to put on the order
| Line | What to write |
|---|---|
| Material | 304 stainless, #4 brushed; 316L for salt air or chlorides |
| Face | 12 × 10 in [305 × 254 mm] |
| Depth | 4 in [102 mm] inside; 4.5 in [114 mm] if the panel PC runs warm |
| Display cutout | per panel drawing, about 7.3 × 5.6 in [185 × 142 mm], ±0.04 in [±1 mm] |
| Operators | one 22.5 mm E-stop, two 22.5 mm pushbuttons, IP66 rated |
| Cable entry | three M12 sealed glands in the rear wall |
| Rating | NEMA 4X / IP66 by the manufacturer; not UL listed |
| Delivery | 10 business days, counted from your approval of the drawing |
You set depth like any other dimension in the custom enclosure builder: width, height, depth and every cutout, built from one piece. Send the panel drawing and your layout with the quote — the drawing package for panel integration lists what to include. To compare catalog bodies first, the enclosure selector filters by usable inside height and width, and HMI enclosures built around one display holds the 8 in 304 stainless housing cut for this panel size, with 7 in and 10.1 in shells of the same family either side of it.
Decide by where the station hangs:
| Environment | Order | Depth |
|---|---|---|
| Indoor, dry or dusty | 304 or painted steel, Type 12 | 102 mm |
| Food line, hose washdown | 304 stainless, Type 4X | 102–114 mm |
| Coast, brine, outdoor | 316L stainless, Type 4X, sun-checked | 114 mm |
Standardizing a fleet? Standard enclosure sizes for interchangeable boxes keeps stations on common bodies, so a future swap stays a bolt-off, bolt-on job.
Enclosures in this article
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 8" HMI enclosure | 304 stainless | 8.39 x 9.98 x 3.92 in | IP65-type front seal with the display installed, manufacturer rated; not UL listed |
| 7" HMI enclosure | 304 stainless | 7.43 x 9.96 x 3.7 in | IP65-type front seal with the display installed, manufacturer rated; not UL listed |
| 10.1" HMI enclosure | 304 stainless | 8.72 x 12.66 x 3.48 in | IP65-type front seal with the display installed, manufacturer rated; not UL listed |
Questions
Can I build the station shallower than 4 in?
Yes, down to about 3.5 in [89 mm] with a bare touch monitor, right-angle cord pigtails and rear glands only. A gland nut and lockring need about 0.5 in [13 mm] of that on their own. Below 3 in [76 mm] you lose the door gasket land and any service loop, so the first rewire turns into pulling the panel out of the door.
Does the IP65 bezel rating on the display seal the whole station?
It seals the front face only, tested with the panel bolted to a flat plate. The rear case, its connectors and any vents are unrated, so the enclosure carries the station. Order the box rated NEMA 4X / IP66 by the manufacturer, not UL listed, and note that NEC 110.28 keeps an IP code from standing in for an enclosure type rating in US installations.
Why do stock enclosures start at 6 in deep?
They are built for backplanes, DIN rail and conduit. One 3/4 in rigid 90° ell with its locknut stands about 2.5 in [64 mm] off the back wall, and NEC 312.6 sets wire bending space at terminals by conductor size on top of that. With power and network landing as sealed cord grips instead, none of that depth is working for you, which is where the shallow station comes from.
Will a 30 W panel PC overheat in a box this shallow?
Not at normal ambients. A 12 × 10 in [305 × 254 mm] steel face at this depth has about 416 in² [0.27 m²] of surface and sheds roughly 4.2 W per °C, so 30 W lifts the inside about 7 °C [13 °F]: 42 °C [108 °F] in a 35 °C [95 °F] plant against the usual 50 °C [122 °F] panel limit. A 60 W mini-PC station doubles the rise; give it 6 in [152 mm] or a bigger face.
How close can the E-stop go to the display cutout?
Center it at least 2 in [50 mm] from the cutout so a gloved hand clears the bezel, and keep every hole 1 in [25 mm] off the door edge so the gasket land stays flat. The 22.5 mm hole takes a contact block about 1.6 in [40 mm] deep, which sits beside the panel rather than behind it, so it costs you no depth.
Does a shallow enclosure change the code clearances?
It changes nothing in front of it. NEC 110.26(A) still wants at least 3 ft [900 mm] of clear working space in front of equipment serviced energized at 0 to 150 V to ground, and if you mount breakers inside, NEC 240.24(A) keeps the highest handle center at or below 6 ft 7 in [2.0 m]. The box may be shallow; the space in front stays as the code sets it.
