Choose an electrical enclosure by checking the installation environment, component layout, mounting method, material, protection requirements, and heat load. Before ordering, confirm the cable entries, door hardware, supplier scope, and shipping arrangements. Outside dimensions alone leave too many of those decisions unresolved.
Work through these seven checks before requesting a quotation. They will help you compare a standard enclosure, a standard model with modifications, or a custom design.
1. Describe the installation conditions
Start with what the enclosure will face at the site. “Outdoor” or “waterproof” leaves the supplier guessing about exposure.
Record whether the enclosure will sit indoors, under shelter, or in direct weather. Include rain, airborne dust, sunlight, ambient temperature, humidity, nearby heat sources, and vibration where relevant. For coastal, chemical, or washdown locations, identify the salt exposure, chemicals, or cleaning method instead of relying on a general description such as “harsh environment.”
Water exposure needs particular care. Rain, splashing, hose-directed water, and immersion are different requirements. Condensation inside the enclosure needs its own review; a rain-protection requirement does not resolve it.
Also describe how people will use the enclosure. Frequent opening, restricted access, or a location that is difficult to service can change the door, lock, mounting, and maintenance requirements.
For exposed installations, the outdoor enclosure design checklist covers rain, sun, drainage, and condensation in more detail.
2. Check the component layout and usable space
Prepare a component list before selecting a catalog size. Include mounting dimensions, connection points, manufacturer clearance requirements, and heat losses where available. Show door-mounted devices as well as equipment on the mounting plate.
Check the proposed layout against the usable mounting area and the space available with the door closed. Allow for:
- Wiring ducts, terminals, and DIN rails.
- Cable glands, connectors, and cable bends.
- The depth of components and door-mounted devices.
- Access for wiring, inspection, and component replacement.
- Planned additions that the project has actually identified.
An enclosure can match the requested outside dimensions and still leave a connector against the door or a cable entry behind a component. Put these details on the layout before approving the size. The electrical enclosure sizing guide explains the dimensional checks without repeating them here.
Identify critical functions in the component list. Ask: “What stops if it fails?” A low-cost relay in a run-permissive circuit may stop a machine even though the PLC controls the sequence. The enclosure budget should account for the exposure that could cause that failure and the work needed to diagnose, repair, and restart the equipment. Component purchase price alone is a poor basis for that decision.
3. Choose the enclosure form and mounting method
The installation method determines how the enclosure is supported, opened, wired, and handled. Compare the physical arrangement before choosing accessories.
| Enclosure form | Typical use | Check before ordering |
|---|---|---|
| Wall-mounted enclosure | Compact controls, distribution, or machine-side equipment | Supporting surface, total installed weight, mounting points, door swing, and cable approach |
| Floor-standing cabinet | Larger control or power assemblies | Base arrangement, frame support, handling and lifting provisions, access, and shipping support |
| Junction box | Cable connections and field wiring | Cable-entry space, cover access, depth, gasket, and grounding provisions |
Names such as “control enclosure” and “distribution enclosure” describe the intended use. They still need a mounting arrangement and a layout suited to the equipment inside.
Check standard products first. A suitable standard enclosure with factory-prepared cutouts or a different mounting plate may meet the project without a fully custom body. Consider custom fabrication when the available dimensions, interfaces, material, or structural arrangement cannot accommodate the requirements. The standard-versus-custom enclosure guide helps separate those options.
4. Match the material and finish to the exposure
Specify the base material and surface treatment together. A request for “steel” does not tell the manufacturer whether the project needs a coated mild-steel body, galvanized sheet, or a particular stainless grade.
| Material or construction | What to evaluate |
|---|---|
| Mild steel with a protective finish | Surface preparation, coating quality, and the suitability of the finished enclosure for the installation |
| Powder-coated steel | Pretreatment, coating adhesion, damage during handling, and protection at cut edges |
| Galvanized steel | Cut edges, welded areas, and compatibility with any additional finish |
| Stainless steel 304 | The actual corrosion and cleaning exposure, fabrication quality, and surface finish |
| Stainless steel 316 | Whether the exposure justifies this grade, plus fabrication and cleaning requirements; the grade alone does not establish suitability |
| Aluminum | Weight, mechanical requirements, surface treatment, and contact with other metals |
| Plastic or fiberglass | UV exposure, impact, fire requirements, temperature, and structural limits for the selected product |
This table is a selection checklist, not a statement that every material or configuration is available from one supplier.
Give each proposed upgrade a reason. A different material grade should address a documented corrosion condition. Greater thickness should answer a load, impact, mounting, or stiffness requirement. Ask the supplier to identify the cost, weight, and delivery implications where they affect the decision.
If a requirement is unresolved, mark it for technical confirmation. Do not silently remove it to reach a price target or assume that the most expensive option resolves the uncertainty.
5. Confirm protection requirements with the openings and door hardware
Record the required IP rating or NEMA Type in the specification, together with the conditions it must address and the documents the project requires.
IEC 60529 defines the IP Code for degrees of protection provided by enclosures. IP markings address access and ingress protection. NEMA Type definitions cover specified environmental conditions and can include requirements beyond the IP Code. NEMA’s enclosure-type guidance explains why the two systems cannot be treated as exact equivalents.
Review the intended configuration, including openings and accessories. A rating for a base enclosure does not settle the suitability of every later modification.
For cable entries and cutouts, confirm:
- Entry direction, cable sizes, gland selection, and gland-plate location.
- Hole dimensions, spacing, and tolerances on the drawing.
- Clearance from components, mounting hardware, and the door.
- Whether openings will be made at the factory or on site, and how cut edges and seals will be finished.
Review the door at the same time. The gasket, latch positions, hinges, and door stiffness work together. Uneven compression or poor alignment can undermine the intended seal. Include windows and other door-mounted accessories in this review.
Where test reports or certification are required, ask which exact enclosure configuration the documentation covers. Confirm responsibility for reviewing modifications before production. Do not infer certification from a rating mentioned in a quotation.
6. Check heat and condensation before finalizing the enclosure
Use component heat-loss data, the expected ambient conditions, and installation details to review temperature inside the enclosure. Direct sun and nearby heat sources belong in that assessment.
Leave room for the proposed thermal equipment in the layout. Fans, filters, heaters, and air conditioners serve different needs and introduce their own installation and maintenance requirements. A heater intended for condensation control does not replace a cooling assessment.
Any vent or thermal accessory must also be reviewed against the protection requirement. Opening a sealed enclosure for airflow changes the configuration you are selecting.
Condensation deserves a separate check, particularly where humidity and temperature vary. Confirm the intended control method and its maintenance needs instead of assuming that a higher ingress rating will keep the interior dry under all conditions.
For the next stage, use the enclosure cooling guide to review fans, filters, heaters, and air conditioners. Final selection still needs the project’s thermal inputs.
7. Agree on supply scope, delivery, and approval responsibilities
Two quotations are only comparable when they include the same work. State whether you need an empty enclosure, mechanical preparation, or a complete electrical assembly.
| Supply scope | Items to define |
|---|---|
| Empty enclosure | Body, door or cover, finish, and the hardware included with that model |
| Mechanically prepared enclosure | Cutouts, mounting plate, rails, gland plates, brackets, seals, windows, and other agreed accessories |
| Full electrical assembly | Components, wiring, testing, documentation, and the parties responsible for electrical design and approval |
These are scope descriptions, not a claim that an enclosure manufacturer provides every level of assembly. Confirm capabilities and required documents with the proposed supplier.
List included and excluded items. Assign responsibility for drawings, technical review, inspection, and approval before production. Engineering should confirm layout, environment, heat, and protection requirements; installation and maintenance teams should check site fit and access. Procurement can then compare quantity, price, delivery, packaging, and documentation on the same basis.
Packaging belongs in that comparison. Specify the transport method and review surface protection, door restraint, separate accessory packing, and pallet or crate support where needed. A damaged coating or distorted door can create work at the installation site even when the fabrication drawing was correct.
For project-specific fabrication, the custom electrical enclosure page describes the information to prepare for a drawing-based inquiry.
Example: reviewing an outdoor enclosure request
The following request is hypothetical. It illustrates missing specification inputs and has not been validated as an enclosure design.
A request specifies an outdoor stainless-steel enclosure and its outside dimensions. Before comparing prices, the buyer checks what remains unresolved:
| Information already provided | Question still open | Next action |
|---|---|---|
| Outdoor installation | Direct rain, sheltered exposure, washdown, or salt exposure? | Describe the site and cleaning conditions |
| Stainless-steel body | Which grade and finish suit those conditions? | Confirm the material specification |
| Outside dimensions | Do the mounting layout, wiring bends, and door devices fit? | Review the usable space on drawings |
| Bottom cable entry | Which cables, glands, holes, and gland plate? | Complete the cable-entry schedule |
| Protection target | Does the proposed configuration, including accessories, meet the requirement? | Confirm the configuration and required evidence |
| Export shipment | How will the door, finish, and loose accessories be protected? | Agree on the packing arrangement |
Heat and condensation remain open until the component data and site conditions are reviewed. Specifying a more expensive stainless grade would not answer those questions. The quotation should identify unresolved items and who will confirm them.
Prepare an RFQ the supplier can review
Send the available information together and mark missing inputs clearly. Avoid letting an empty field become an assumed requirement.
| RFQ item | Information to provide |
|---|---|
| Project and site | Application, installation conditions, protected function, and consequence of failure |
| Drawings and layout | Proposed dimensions, mounting arrangement, components, usable-space requirements, and drawing revision |
| Construction | Material, finish, door arrangement, and required accessories |
| Protection and openings | IP or NEMA requirement, cable-entry schedule, cutouts, glands, windows, and required evidence |
| Thermal conditions | Component losses, ambient conditions, solar exposure where applicable, and condensation concerns |
| Supply and delivery | Included and excluded work, quantity, required date, destination, packaging, and inspection documents |
| Open items | Information still needed, the responsible person, and what must be confirmed before production |
You can use this summary to open the inquiry:
Please quote an [empty / mechanically prepared / fully assembled] enclosure for [application and installation conditions]. The proposed material, finish, and dimensions are [details], with [cable entries, cutouts, and accessories]. It will house [components and protected function]. Required quantity, delivery, packaging, and documents are [details]. Please identify exclusions and items requiring confirmation before production.
Use the FN Enclosure contact page to send the project summary and confirm how to share drawings. Include the current drawing revision and identify any decisions that still need engineering review.
Frequently asked questions
Check the usable mounting area and the space available with the door closed. Include components, wiring ducts, terminals, cable bends, door-mounted devices, and service access. Review heat and planned additions before selecting a catalog size.
Choose the material and finish for the actual installation conditions. Coated steel, stainless steel, aluminum, and non-metallic enclosures have different strengths and limits. For stainless steel, confirm the grade against the corrosion and cleaning exposure; the grade alone does not establish suitability.
Use the system required by the project specification, and confirm what protection and documentation it requires. IP ratings and NEMA Types are not exact equivalents. Review the proposed enclosure configuration, including cable entries, windows, vents, and other modifications.
Consider custom fabrication when available standard dimensions, interfaces, materials, or structural arrangements cannot accommodate the project. If the basic enclosure fits, a standard model with factory-prepared cutouts or a different mounting plate may be sufficient.
Component price alone does not determine the protection needed. An inexpensive part can sit in a critical control or interlock path. Assess its exposure and the consequence of failure, then specify the enclosure features that address those risks.
Only if those items are explicitly included. An empty enclosure, a mechanically prepared enclosure, and a complete electrical assembly are different supply scopes. Confirm included work, exclusions, testing, required documents, and approval responsibilities before comparing quotations.