Buy a stocked catalog box when a standard size, the right NEMA type and no cutouts do the job. Order it as a custom build from the manufacturer the moment the job needs a non-standard depth, 316L stainless for salt air or brine, or holes placed for your own devices. Custom stainless enclosures are delivered in 10 business days, counted from your approval of the drawing, from a minimum of one piece. The quick test is to count modifications. Zero or one drilled gland hole points to a catalog box. Two or more holes, an odd depth or a 316L grade points to a custom order, and at 10 business days the custom route rarely costs you the schedule.
The three routes to a box
You can buy an enclosure box in three places, and each fits a different job. Electronics distributors carry the small diecast aluminium and plastic boxes, roughly hand-sized, that suit prototypes and bench builds. Industrial automation distributors and manufacturers' standard lines carry the ladder of painted-steel and stainless sizes, from Type 12 indoor panels up to Type 4X washdown boxes. The manufacturer's custom shop builds your size, your material and your cutouts from one piece, with a drawing you approve before anything is cut.
Count your modifications before you pick a route. A stocked ladder offers a fixed grid of heights, widths and depths, so your layout bends to the box. A custom build bends the box to your layout, and the cost is a drawing to approve, not a long wait.
| Route | What you choose | The catch | Fits when |
|---|---|---|---|
| Electronics distributor | small diecast aluminium or plastic boxes | indoor ratings, no cutout service | prototypes, bench gear, junction taps |
| Automation distributor or standard line | a fixed ladder of sizes in painted steel or 304 stainless, Type 12 to Type 4X | every hole is yours to drill | standard panels, one or two gland holes |
| Manufacturer custom | your material, size, NEMA type and cutouts, one piece up | the drawing approval starts the clock | 316L, odd depths, windows, Type 6P |
The location sets the NEMA type first
Decide the rating before the route. ANSI/NEMA 250-2020 puts Types 1, 2, 5, 12, 12K and 13 in the indoor group and Types 3, 3X, 3R, 3RX, 3S, 3SX, 4, 4X, 6 and 6P in the outdoor group. Match the box to the environment first, then ask which route can sell that type in a size that fits.
Dry indoor panels take Type 1 or Type 12, with dust and dripping coolant pushing you to Type 12 or 13. Rain and sleet outdoors start at Type 3R. A washdown hose needs Type 4, and corrosive washdown, salt air or brine need Type 4X in 316L. Temporary submersion is Type 6 (nearest IP67) and prolonged submersion is Type 6P (nearest IP68). Class I Div areas take Type 7 or Type 9 enclosures, which we do not build; buy those from a hazardous-location specialist.
Our enclosures carry manufacturer ratings: a wall-mount stainless box is rated NEMA 4X-type / IP66 by the manufacturer; not UL listed. NEMA writes the type definitions and never tests or certifies a box. The NEMA enclosure types guide explains each type, and the NEMA 4 vs 4X vs IP66 comparison sorts out the washdown and corrosion tests behind them.
| Location | NEMA type to order | Route that sells it |
|---|---|---|
| Dry indoor panel | Type 12 | stocked catalog size |
| Outdoor rain and sleet | Type 3R | stocked catalog size |
| Washdown hose, non-corrosive | Type 4 | catalog size; custom when cutouts pile up |
| Washdown with chemicals or salt | Type 4X in 316L | custom direct |
| Temporary or prolonged submersion | Type 6 or 6P | custom direct |
| Flammable gas or dust (Class I Div) | Type 7 or 9 | hazardous-location specialist; we do not build these |
Size: where the stocked ladder stops fitting
The stocked stainless wall-mount ladder here runs from 6 x 4 x 4 in to 60 x 36 x 16 in (H x W x D). Each box has a hinged gasketed door, a removable mounting panel and wall-mount feet, and the stainless enclosure size finder filters the range by grade and size. Work the size out from the layout. Take each device's depth from its datasheet, add about 3 in [75 mm] of wiring depth behind the deepest device, and keep 20-25% spare DIN rail for later additions. The minimum-depth method for DIN rail layouts walks through that sum.
Depth is the dimension stocked ranges miss most often. A deep drive or a row of contactors can fit every stocked width and still want a depth between the standard steps. When several panels share one design, a single stocked size across all of them beats a special depth for each, as the standard sizes planning article argues. If a stocked size holds your layout, buy it. When nothing on the ladder reaches your depth, a custom depth is the cheapest special you can order.
Cutouts: the change that triggers custom most often
Drill one or two 22.5 mm pushbutton holes on site and the box works for you; a hole saw, a deburring pass and a rinse at the edge is the whole job. What the panel keeps after the drill is its own question: the article on the rating a panel keeps after you cut it separates clean gland holes from cuts that leak. On a washdown box, a rough, heat-tinted edge is where rust starts, and wet-dry cycling finishes it; the 316L wet-dry rusting article shows the pattern before you blame the grade.
Windows, display cutouts and multi-gland plates are different work. Each cutout must hold gasket compression around its whole perimeter, and a factory-cut edge keeps the finish that a field grinder cannot. When cable entry is the crowd, a gland plate ordered with the box beats a row of single holes. One mismatch can also be solved from the other side of the hole: the page on finding a 72 x 72 mm controller replacement for a non-standard DIN cutout shows a device swap saving the whole special-cutout order.
Count two or more cutouts, or any display window, and order them factory-cut. From one piece, the custom route is the same 10 business days.
Material: five choices and where each wins
The custom line builds in 304 stainless with a #4 brushed finish, 316L, powder-coated carbon steel in RAL 7035, aluminium, polycarbonate and fiberglass. The 304 vs 316L guide carries the full metallurgy; the short version for a buyer:
| Material | Buy it for | The catch |
|---|---|---|
| 304 stainless, #4 brushed | indoor washdown, food and beverage, most outdoor sites | chloride deposits can pit it even at room temperature |
| 316L stainless | salt air, brine, chlorides, pharma, chemical areas | the premium buys pitting resistance, not a higher temperature limit |
| Powder-coated carbon steel, RAL 7035 | dry indoor panels | the first scratch outdoors is the first rust spot |
| Aluminium | light and mobile builds | the softest surface of the metals here |
| Polycarbonate or fiberglass (FRP) | chemical splash, non-metallic specs | a lower continuous-temperature ceiling than steel |
Carry one temperature line into the washdown discussion: both 304 and 316L give way to chloride stress-corrosion cracking above about 60 °C (140 °F), and the molybdenum in 316L raises pitting and crevice resistance without moving that threshold.
Heat: the check that moves you up a size, not to custom
Heat is the buying check people skip and then pay for at commissioning. Worked example, with illustrative inputs you replace with your own. The box is sealed stainless, indoors at 25 °C ambient, carrying 60 W: a 24 V DC supply, a compact PLC and a small HMI. The wall coefficient is k = 3.7 W/m²K for stainless, the value this site's heat guides use, bundling convection and radiation. The interior limit is 40 °C, the rating most drives and electronics carry.
- Allowed rise: 40 - 25 = 15 K.
- Wall area needed: 60 W ÷ (3.7 W/m²K × 15 K) = 1.08 m².
- Candidate A, 20 x 16 x 8 in (0.508 x 0.4064 x 0.2032 m): area ≈ 0.785 m², so the rise is 60 ÷ (3.7 × 0.785) = 20.7 K and the interior sits at 45.7 °C — 5.7 K over the limit.
- Candidate B, 24 x 20 x 10 in (0.610 x 0.508 x 0.254 m): area ≈ 1.19 m², the rise is 60 ÷ (3.7 × 1.19) = 13.6 K, and the interior sits at 38.6 °C — under the limit.
| Candidate | Wall area | Rise over ambient | Interior at 25 °C ambient |
|---|---|---|---|
| 20 x 16 x 8 in | 0.785 m² | 20.7 K | 45.7 °C, over the 40 °C limit |
| 24 x 20 x 10 in | 1.19 m² | 13.6 K | 38.6 °C, inside the limit |
Both candidates are ordinary ladder sizes, so heat pushes you up a size rather than into a custom order. Ambient moves the answer more than wattage does. At 35 °C the allowed rise falls to 5 K, and the same 60 W wants 60 ÷ (3.7 × 5) = 3.24 m² of wall. Only the top of the stocked ladder, 60 x 36 x 16 in at about 4.8 m², reaches that passively. Below that, a filter fan buys airflow at the cost of the Type 4X rating; what a fan costs a NEMA 4X enclosure has the trade, and a closed-loop cooler keeps the rating sealed. A drive is the usual reason a box runs hot; the VFD enclosure article works that case end to end.
The decision, case by case
| Your job | Buy it where |
|---|---|
| Bench or prototype box, indoor, hand-sized | electronics distributor, stocked |
| Indoor panel, Type 12, stocked size, one or two drilled gland holes | automation distributor or standard line |
| Washdown hose, 304, a window and pilot-light holes | custom direct: factory cutouts, same 10 business days |
| Salt air, brine or chemical washdown, 316L Type 4X | custom direct, from one piece |
| Submersion on the table | custom direct, Type 6 or 6P |
| Class I Div gas or dust | hazardous-location specialist; we do not build Type 7 or 9 |
| A deep layout no stocked depth reaches | custom direct; depth is the cheapest special to change |
Stocked when the ladder fits, custom when your layout does not. Order a custom stainless enclosure when your modification count lands at two or more.
What to put on the order
| Line | What to write |
|---|---|
| Material and finish | 316L, #4 brushed — or 304, painted steel RAL 7035, aluminium, polycarbonate, fiberglass |
| Rating | NEMA type and IP code, for example Type 4X / IP66 |
| Outside size | H x W x D, inches first with mm in brackets |
| Cutouts | each hole with position and size: 22.5 mm pushbuttons, gland holes, window to the device drawing |
| Mounting | wall-mount feet, removable panel, hinge side, door swing |
| Climate option | none, filter fan, or closed-loop cooler with the interior target in °C |
| Quantity | from one piece |
| Drawing | approve the returned drawing; approval starts the 10 business days |
Configure the box in the 3D enclosure builder or send the layout for a quote; the quote comes back by email with a drawing to approve, and the 3D model to finished box walkthrough shows each step. Mark the finished panel with its enclosure type number, as NEC 409.110 requires for industrial control panels, so the label matches what you ordered. Orders are placed and paid through the checkout of Industrial Monitor Direct, who builds, ships and supports every box. While you wait, plan the wall: NEC 110.26(A) asks for at least 3 ft (900 mm) of working depth in front of equipment likely to be serviced while energized, with the door opening at least 90 degrees, and the enclosure mounting guide collects the mounting numbers.
Catalog dimensions to compare
Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 20 × 16 × 8 in | 316L stainless | 20 x 16 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 10 in | 316L stainless | 24 x 20 x 10 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 316L stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 316L stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Can I order just one custom enclosure box?
Yes. The minimum quantity is one piece, and the delivery promise is the same as for a larger run: delivered in 10 business days, counted from your approval of the drawing. A one-off carries the full setup, so its per-unit number runs higher than a batch of ten of the same design, but you will not be pushed to a case pack or a batch minimum.
When is a custom enclosure worth it instead of a catalog box?
Count the modifications the catalog box needs. Zero or one drilled gland hole: buy the stock box and drill it yourself. A depth no stocked size reaches, a 316L grade for salt or brine, a display window, or two or more holes: order it factory-built. At 10 business days from drawing approval, the custom box usually lands before the panel build needs it.
What size box do I need for a PLC, a power supply and some DIN modules?
Add depths instead of guessing. Take the deepest device's datasheet depth, add about 3 in [75 mm] for wiring behind it, and keep 20-25% spare DIN rail. A 16 x 12 x 8 in box holds a compact PLC, a 24 V DC power supply and roughly a dozen DIN modules at that rule; check each device's own depth before you order.
Does the enclosure need to be UL listed?
Ask the specification first: some US projects and inspectors require a listing, and NEC 110.28 states that IP ratings are not a substitute for enclosure type ratings, so the NEMA type stays on the order either way. Our enclosures are rated by the manufacturer and not UL listed; where a listing is required, buy the listed box from a maker that carries it.
How fast can I get a stainless enclosure box?
A stocked catalog size from a distributor reaches you in days. A custom stainless enclosure is delivered in 10 business days, anywhere in the world, counted from your order or, for custom work, from your approval of the drawing. If the schedule is shorter than a week and a stock size fits, the stock box with one drilled hole is the faster buy.
