Figure 1. Board selection starts with the circuit schedule, device space, and planned reserve.
A request for a “12 way distribution board” can sound specific, but it leaves the layout unresolved. One project may use mostly single-pole devices; another may need multi-pole devices, an incomer, surge protection, metering, or more terminal space. The same number on two product labels does not promise the same usable configuration.
Quick answer: Choose a distribution board from a verified circuit and device schedule, then confirm how the manufacturer defines ways and usable space for that specific board. The required size depends on the supply system, the number and pole arrangement of outgoing devices, incomer and accessory space, installation conditions, and planned expansion. Single-phase and three-phase distribution boards should not be compared by the advertised way count alone.
This guide turns a rough way-count request into a specification a supplier can review. Electrical design, protection coordination, load calculations, and installation still belong with qualified professionals.
The number of ways describes the outgoing capacity or positions provided by a particular distribution board system. However, way, module, pole, and outgoing circuit are not universally interchangeable terms.
A single-pole protective device may use one position in one product system. A multi-pole device occupies adjacent positions. An RCCB, RCBO, surge protective device, main switch, meter, or another accessory may require a different amount of space. Some boards separate the incomer from outgoing ways, while other enclosure layouts use shared modular space. Three-phase boards can also describe their outgoing capacity differently from single-phase boards.
Use the product data sheet as the final reference: check how that manufacturer counts ways, which devices the system accepts, and what usable space remains after the specified equipment is installed.
Figure 2. Check outgoing devices, the incomer, accessories, terminals and cables, and reserve against the exact board data sheet.
The word size can refer to several different things: the external dimensions of the enclosure, the number of rows, the modular capacity, the advertised ways, or the electrical ratings of an assembled board. A useful quotation needs these meanings separated.
Start with the current circuit schedule. It identifies each outgoing circuit, its function, and the pole arrangement specified by the electrical designer. Ten outgoing circuits do not always occupy ten identical positions.
Keep the schedule current. An added EV charger, photovoltaic system, machine, or sub-distribution board may change the device list and enclosure requirement. Send those changes back to the project designer instead of estimating them from a blog article.
The device list also has a physical footprint. Check the references, widths, and pole arrangements of the selected MCBs, RCCBs, RCBOs, SPDs, switches, and other devices against the intended board system.
Do not assume that two product families with the same device name have the same width or approval for the assembly. “MCB” alone does not establish mechanical fit, busbar compatibility, terminal arrangement, or assembly performance.
Outgoing circuits are only part of the board. The design may also call for a main switch or protective incomer, surge protection, metering, control equipment, neutral and protective-earth terminals, labels, or communication accessories.
Then check cable entry and conductor bending space. A board can have enough apparent device positions and still be unsuitable if it cannot accommodate the specified cables, terminals, or entry direction. Ask for a dimensional drawing; a front-view photograph is insufficient.
A problem belongs on the drawing before it reaches the people on site.
Reserve space should solve a foreseeable need. No spare capacity can make later changes difficult, while an unnecessarily large enclosure costs more, takes wall space, and may complicate installation.
There is no spare-way percentage that works for every country and project. Base the reserve on foreseeable expansion, the governing design rules, and the manufacturer’s configuration. Record its purpose in the schedule so the supplier does not mistake it for unused space.
Indoor or outdoor location, surface or flush mounting, material, cable entry, temperature, exposure, and maintenance access can all affect the enclosure choice. If an IP rating is required, state the required rating and the actual installation conditions.
IEC 60529 classifies degrees of protection provided by enclosures through the IP Code. An IP rating is not a promise that an enclosure is suitable for every outdoor location, cleaning method, or exposure. Final suitability depends on the complete product, installation, sealing, maintenance, and local requirements.
Figure 3. An IP65 label is one input; exposure, cable entries, material, and maintenance also need review.
A 12 way single-phase board and a 12 way three-phase board are not equivalent simply because the labels match. Internal layout, busbar system, accepted device combinations, and even the way-count convention can differ.
A three-phase design may include both single-pole and multi-pole outgoing devices. The electrical designer determines the phase arrangement; the buyer should not infer it from the advertised way count. Because multi-pole devices also take more adjacent space, multiplying or dividing that count does not create a reliable universal circuit total.
| Vérifier | Single-phase quotation | Three-phase quotation |
| Supply information | Provide the project supply and neutral arrangement | Provide the three-phase system information and whether the design requires a neutral |
| Device schedule | List the specified single-pole and multi-pole devices | List the mix of single-pole and multi-pole devices and the designer-approved phase arrangement |
| Meaning of ways | Confirm the definition in that series data sheet | Confirm exactly how the manufacturer states outgoing and triple-pole capacity |
| Review documents | Circuit schedule and component list | Circuit schedule, component list, and the professionally reviewed phase arrangement |
IEC 61439-3:2024 defines requirements for a specific class of low-voltage distribution boards intended to be operated by ordinary persons. Whether that standard applies to a project or product must be confirmed from the assembly type, intended use, manufacturer documentation, and local requirements. The standard name should not be used as a blanket claim for every distribution board.
A search for a 12 way or 24 way distribution board gives a supplier a useful starting point, not a finished specification. Treat the number as a prompt to check the actual layout.
| Advertised range | Comment l'interpréter ? | What to confirm before ordering |
| 4 to 8 ways | A compact range, not automatic proof that it suits a small project | Actual devices, pole count, incomer, accessories, and expansion requirement |
| 12 ways | A common comparison term, not a universal promise of 12 identical circuits | Board type, manufacturer’s counting method, and device widths |
| 15 to 18 ways | Capacity that may belong to a particular enclosure family or compact layout | Model dimensions, internal arrangement, cable entry, and component list |
| 24 ways | A common search and purchasing term that still needs a complete schedule | Device mix, reserved space, maintenance access, and installation environment |
| 36 to 54 ways | A larger enclosure range, not automatic evidence of better safety or suitability | Assembly design, manufacturer limits, project conditions, and professional review |
OOHMAGE’s current distribution-box category lists the HA series across a 4–54 way range and the HT series in 15, 18, and 24 way options. These are selection ranges, not a promise that every model is a complete three-phase assembly or fits a particular project. Send the layout, component dimensions, installation conditions, quantity, and destination market so the exact model can be confirmed.
Figure 4. Published HA and HT way ranges are a starting point; confirm the exact model and internal layout.
Give the destination country or region and the supply information from the project documents. Terminology, required documentation, and installation rules vary by market; a sales team should not have to infer the system from “distribution board.”
Attach the current panel schedule or an equivalent circuit list. State each circuit’s function and specified pole arrangement. Mark future circuits separately so the supplier can distinguish the installed requirement from the space being reserved.
List the planned MCB, RCCB, RCBO, SPD, switch, meter, and other device references when they are known. If brands are still open, send the design requirements and verified dimensions. Critical protection parameters should come from the design, not a supplier’s guess.
State whether the plan includes a main switch, protective incomer, metering, surge protection, control equipment, communication accessories, or extra terminals. For the proposed board, ask which of these use advertised ways and which require separate space.
Name the additions you expect instead of adding an arbitrary spare percentage. A production line, extra floor, EV charging circuit, or photovoltaic connection may call for a different review from unspecified “future use.” The project designer should confirm the electrical implications.
State whether the enclosure is installed indoors or outdoors, surface-mounted or flush-mounted, and whether it faces dust, water jets, heat, corrosion, direct weather, or restricted maintenance access. Include the required IP rating and cable-entry direction, but allow the supplier and project professional to check the complete suitability.
Ask for the exact model, dimensional drawing, definition of ways, accepted device arrangement, relevant ratings, and available conformity documents. For a configured assembly, include whatever its technical reviewer needs. A quotation without an identifiable model and supporting data is difficult to verify.
Figure 5. Send the circuit schedule and installation details, then request a model and document set that can be reviewed.
Copy the following table into an inquiry alongside the design schedule. It keeps the way-count request connected to the information the supplier needs for a meaningful response.
Clear details are a quiet form of respect for the next person who relies on them.
| Champ « Appel d'offres » | Information from the buyer | Confirmation expected from the supplier |
| Marché cible | Country or region and applicable project requirements | Available models and document scope for that market |
| Supply system | Single-phase or three-phase information and neutral arrangement from the project | Whether the proposed series can support the documented system |
| Circuit schedule | Circuit quantity, function, and pole arrangement | Actual occupied positions and proposed board configuration |
| Appareils | References or dimensions for MCBs, RCCBs, RCBOs, SPDs, incomer, and accessories | Mechanical fit, available space, and required accessories |
| Ways and reserve | Requested way count and documented expansion plan | Manufacturer’s definition of ways and remaining usable capacity |
| Annexe | Material, mounting method, environment, and required IP rating | Enclosure options, dimensions, and application boundaries |
| Cable entry | Entry direction, quantity, and relevant drawings | Available entries, terminal access, and internal space |
| Détails de la commande | Quantity, packaging, labels, destination, and required documents | Model-specific commercial and documentation response |
Treating the way count as a complete design: The number does not confirm the supply system, protection, ratings, device compatibility, or installation conditions.
Comparing only external dimensions or current labels: A large enclosure can still have the wrong internal system, while an electrical rating does not describe available device space.
Assuming equal numbers mean equal capacity: Single-phase and three-phase boards, or boards from different manufacturers, can use different layouts and counting conventions.
Forgetting non-outgoing equipment: The incomer, surge protection, metering, terminals, and cable space can change the required arrangement.
Using IP65 as an unlimited waterproof claim: IP65 is a defined enclosure protection classification. It does not by itself confirm suitability for immersion, every outdoor exposure, or an installation with poorly maintained entries and seals.
Selecting the biggest enclosure without a plan: More empty space is not automatically the best specification. Reserve should be linked to a documented expansion need and the approved design.
Accepting an untraceable quotation: A useful offer should identify the model, dimensions, way-count definition, configuration boundaries, and available technical documents.
The label alone cannot answer this. Check whether the specified multi-pole devices, incomer, SPD, metering, terminals, and reserve fit within that exact board’s usable capacity. A 12 way model may pass or fail that check; use the manufacturer’s data.
Do not assume the breaker count equals the advertised way count. Check the manufacturer’s definition of a way, the board type, and each device’s width and pole arrangement. Ask for a layout showing the proposed devices in the exact model.
A qualified professional develops the system, load, circuit, phase, and protection design. The resulting schedule is then checked against the board’s way convention, device space, incomer, ratings, enclosure, environment, and project rules. A universal online formula cannot replace that process.
Send the destination market, supply system, circuit schedule, component list, incomer and accessory requirements, requested ways and reserve, mounting and environment, cable entry, quantity, packaging, and documentation requirements.
IP65 describes a degree of enclosure protection under the IP Code. Outdoor suitability still depends on the complete enclosure, exposure, mounting, temperature, material, cable entries, seals, maintenance, and local requirements. Provide the actual environment for review.
The best fit is the board or enclosure whose documented configuration matches the circuit schedule, device footprint, supply system, installation environment, and planned expansion. A higher way count alone does not establish that fit.
Good advice still makes sense after the sale.
OOHMAGE supplies IP65 electrical distribution box ranges for project selection, including the HA 4–54 way and HT 15/18/24 way options shown on its current category page. For model confirmation, send the panel schedule or component list, required ways, mounting and cable-entry needs, installation environment, quantity, destination market, and required documents.
Review OOHMAGE IP65 electrical distribution boxes or the HT 15 18 and 24 way distribution box range before sending your inquiry.
