Project design turns an electrical panel from a list of requirements on paper into a manufacturable engineering file. Devpan’s design team carries out load analysis, single-line diagrams, protection coordination, busbar and cable sizing, thermal calculations and layout studies in line with IEC / TS EN 61439 and, for medium voltage, IEC 62271-200.
How Does Our Design Team Work?
Devpan’s design group is made up of engineers experienced in electrical engineering, mechanical design, control systems and software integration, cost analysis and project management. The team does not see a project as just producing drawings: it studies the customer’s operating scenario and builds a solution that meets, and wherever possible exceeds, expectations.
That is why the design process is coordinated from start to finish. The customer’s project team, equipment suppliers, manufacturers and Devpan’s own production, quality and field units all work from the same data set, so a component change or layout revision is reflected in every related document at the same time.
Our project engineers stay in constant contact with the production department and site installation teams to ensure design safety. Practical constraints met in production feed back into the design, and experience from the field becomes input for the next project.
Every panel is built once in a digital environment before it goes into production.
The single-line diagram, layout and enclosure details are developed on the same model, and the wire, terminal and label lists are derived from it. This way, mismatches that would otherwise appear on site are caught before production starts.
Thermal behavior, short-circuit withstand and the level of internal separation are checked at the design stage under IEC 61439; the documents sent for customer approval are the result of these verifications.
Revisions are recorded with a version number, and only the latest approved version is used by the production, assembly and test teams.
The customer’s single-line diagram, site dimensions and panel layout constraints are also assessed at this stage; details such as door opening direction, cable entry points and service space are settled before manufacturing starts.
The Design Process: Six Stages
Every project goes through the six stages below. Moving back between stages is allowed: a finding during verification can trigger the layout or material selection step again if needed.
Requirements and Load Analysis
The facility’s load list, operating scenario, diversity factor, short-circuit power and ambient conditions are established. These data set all the boundary conditions of the design.Creating the Single-Line Diagram
The supply arrangement, breaker and switch selection, selectivity scheme, and metering and protection points are defined on the single-line diagram.Layout and Thermal Calculation
Components are placed in the enclosure volume; power losses are added up, the internal temperature rise is calculated and, if necessary, climate control is sized.Material Selection and Busbar Sizing
Busbar and cable cross-sections, insulator spacing and all components are selected according to current, short-circuit and temperature criteria.Verification and Customer Approval
The design is checked against the verification clauses of the standards; revisions are incorporated and the project is submitted for customer approval.Preparing the Production File
Manufacturing drawings, wire and terminal lists, the label list and assembly instructions are derived from the approved project and released to production.
Engineering Documents Delivered
The document set produced at the end of the design process is used throughout the panel’s life cycle. The table below summarizes our standard delivery package.
| Document | Content | Why it matters |
|---|---|---|
| Single-line diagram | One-line representation of the supply, protection, metering and distribution structure | Makes the whole system understandable at a glance |
| Power and control schematics | Detailed circuit drawing of each functional unit | Basis for assembly, commissioning and fault finding |
| Panel layout drawing | Front view, internal layout and mounting plate arrangement | Ensures accessibility and ease of maintenance |
| Thermal load calculation | Component power losses and internal temperature-rise calculation | Prevents overheating and premature aging |
| Short-circuit withstand verification | Check of dynamic and thermal stresses on the busbar system and connections | Preserves mechanical integrity during a fault |
| Bill of materials (BOM) | Complete component list with brands, models and ratings | Clarifies procurement and cost planning |
| Wire and terminal lists | Numbered connection and field cable schedule | Ensures error-free connections on site |
| Labeling and documentation | Label list, operation and maintenance file | Required for handover and operational continuity |
Standards Applied in Design
Our panels are designed and verified to the following standards, depending on the product family and voltage level.
| Standard | Scope |
|---|---|
| TS EN / IEC 61439-1 | Low voltage switchgear and controlgear assemblies – general rules |
| TS EN / IEC 61439-2 | Power switchgear and controlgear assemblies (main distribution boards) |
| TS EN / IEC 61439-3 | Distribution boards (sub-distribution applications) |
| IEC 62271-200 | Metal-enclosed medium voltage switchgear up to 36 kV |
| IEC 60529 | Degrees of protection of enclosures against solid objects and water (IP) |
| IEC/TS 61641 | Assessment of behavior under internal arcing faults |
| IEC 60947 series | Switching devices: circuit breakers, switches, contactors and protection relays |
| IEC 60204-1 | Safety of machinery – electrical equipment of machines |
Design Verification Criteria
A design is not finished just because the drawings are complete. A project is not released to production until all of the points below have been verified.
- Temperature rise: Component power losses are added up and the internal temperature rise is verified, taking the enclosure surface and ventilation into account.
- Short-circuit withstand: The busbar system and connection points are checked against the dynamic and thermal effects of the prospective short-circuit current.
- Degree of protection: Enclosure, door, gasket and cable gland details are designed to achieve the target IP rating.
- Form of separation: Barriers, compartments and terminal separation matching the required form are verified on the layout.
- Insulation coordination: Clearances and creepage distances are checked against the rated insulation voltage.
- Selectivity and protection: Selectivity curves between levels are compared to prevent unnecessary tripping.
- Mechanical strength: Transport, lifting and installation loads are taken into account in the enclosure design.
- Maintenance access: Meters, terminals and breakers are positioned for operator ergonomics.
Common Design Mistakes
- Choosing an unrealistic diversity factor, so the panel ends up oversized or undersized.
- Skipping the thermal calculation, so components in a closed panel exceed the temperature limits in their catalogs.
- Not confirming the short-circuit power with the utility, so the busbar system is designed with insufficient withstand.
- Not clearly defining the form of separation in the contract, leading to costly revisions during production.
- Not detailing cable entry direction and glands, so the target IP rating is lost on site.
- Leaving no spare space or spare outgoing feeders for future expansion.
At a Glance
- Definition: Panel design is the production of all engineering outputs, from electrical calculations to the production file.
- Scope: From 0.4 kV low voltage switchboards to 36 kV medium voltage switchgear.
- Reference standard: IEC / TS EN 61439 series; IEC 62271-200 for medium voltage.
- Key outputs: Single-line diagram, power and control schematics, layout drawing, thermal calculation, bill of materials.
- Verification: Temperature rise, short-circuit withstand, degree of protection and form of separation are checked at the design stage.
- Delivery: The project file goes through customer approval before production.
Frequently Asked Questions
What is electrical panel project design?
Electrical panel project design is the process of turning a facility’s load requirements into a manufacturable engineering file by preparing the single-line diagram, protection scheme, busbar and cable sizing, panel layout and thermal calculation.
What information do you need from us for the design?
A load list, supply voltage and short-circuit power, the required degree of protection and form of separation, installation conditions, preferred brands and, if available, the specification and existing drawings are enough.
How long does the design of a panel project take?
It depends on the scope of the project and the level of detail in the specification, so we do not publish a standard lead time. Once the number of panels, the complexity of the single-line diagram and the speed of the approval cycle have been assessed, we share a project-specific schedule for the design stage.
What is IEC 61439 design verification?
It is the set of assessments the standard requires at the design stage for topics such as temperature rise, short-circuit withstand, dielectric properties and mechanical operation. Verification can be done by testing, calculation or design rules.
Do you prepare retrofit designs for existing panels?
Yes. We establish the current state through site measurements and a review of existing documents, then prepare a revised design for additional loads and new functions.
In which formats are design outputs delivered?
Drawings are delivered in DWG and PDF, lists in XLSX and the document set as a digital project file. A printed file can also be prepared on request.
Do you also design medium voltage switchgear?
Yes. Single-line, protection, interlocking and layout design of metal-enclosed switchgear up to 36 kV is carried out to IEC 62271-200.
How do you keep design and production aligned?
The project engineer works from the same file as the production and assembly teams; revisions are managed under a single version number and only the approved version is released to production.
You May Also Be Interested In
- Project Management – our approach to planning, tracking and reporting
- Automation & SCADA – control and monitoring systems
- Form Separation – IEC 61439 forms and separation levels
- IP Protection Class – enclosure protection ratings
- Copper Current Carrying Capacities – busbar sizing tables
- Low Voltage Panels – DevPanel, DevControl, DevBox
- Panel commissioning and maintenance service
Let’s Design Your Project Together
Share your load list and specification, and Devpan’s engineering team will quickly send you a preliminary single-line diagram, enclosure dimensions and an estimated delivery time.
We follow the same process for retrofitting an existing panel, increasing capacity or designing a second supply.
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