Custom Electrical Control Panel Manufacturing: OEM/ODM Process, Lead Time & Certifications

Introduction

For machine builders, system integrators, and EPC contractors, sourcing custom electrical control panels from a manufacturer rather than building them in-house offers significant advantages: lower cost, faster delivery, access to specialized manufacturing capabilities, and the ability to focus internal resources on core competencies.

But working with a custom panel manufacturer — especially one in China — requires understanding the process, the standards, and the questions to ask before placing an order. This guide covers the complete OEM/ODM process for custom electrical control panels, from initial inquiry to delivery.

OEM vs ODM: What Is the Difference?

OEM (Original Equipment Manufacturer)

In the electrical panel context, OEM means the manufacturer produces panels to your design and specifications. You provide the drawings, component list, and wiring diagrams. The manufacturer builds to your specification and applies your brand label. You own the design.

OEM is appropriate when you have an established panel design that you want to outsource for cost or capacity reasons, or when you need to maintain design control for proprietary reasons.

ODM (Original Design Manufacturer)

ODM means the manufacturer designs the panel based on your functional requirements and then produces it. You specify what the panel must do (motor ratings, protection functions, communication requirements, IP rating, etc.) and the manufacturer handles the detailed design, component selection, and documentation.

ODM is appropriate when you do not have in-house panel design capability, when you want to leverage the manufacturer's application expertise, or when you need a complete solution including design, manufacturing, and documentation.

The Custom Panel Manufacturing Process

Step 1: Technical Inquiry

A complete technical inquiry should include:

• Application description (what the panel controls or distributes)
• Electrical requirements: voltage, frequency, rated current, short-circuit level (Icc) at the installation point
• Protection requirements: overcurrent, earth fault, motor protection functions required
• Communication requirements: Modbus RTU, Profinet, Ethernet/IP, or other protocols
• Environmental requirements: IP rating, ambient temperature range, altitude, humidity
• Enclosure material: steel, stainless steel, GRP
• Standards and certifications required: IEC 61439, CE, UL, CCC, or others
• Quantity: prototype + production volume, or production only
• Delivery requirements: lead time, port of delivery, Incoterms

Step 2: Technical Review and Quotation

The manufacturer reviews the inquiry and prepares a technical proposal including:

• Proposed single-line diagram (SLD) or block diagram
• Component list with brand and model numbers
• Enclosure dimensions and layout sketch
• Price and lead time
• Clarification questions on any ambiguous requirements

At this stage, it is important to review the proposed component brands carefully. Specify acceptable brands for critical components (circuit breakers, contactors, PLCs) to avoid substitution with unfamiliar brands.

Step 3: Design Approval

For OEM orders, the manufacturer produces detailed wiring diagrams based on your design. For ODM orders, the manufacturer produces the complete design package for your review and approval. The design package typically includes:

• Single-line diagram (SLD)
• Wiring diagrams (schematic and connection diagrams)
• Panel layout drawing (front view, internal layout)
• Component list with part numbers
• Cable schedule

Do not proceed to manufacturing without written approval of the design package. Changes after manufacturing begins are expensive and cause delays.

Step 4: Manufacturing

Manufacturing typically proceeds in the following sequence:

1. Enclosure fabrication or procurement
2. DIN rail and cable duct installation
3. Component mounting
4. Busbar installation and connection
5. Internal wiring (power and control circuits)
6. Cable gland installation and external cable termination
7. Label application (component labels, terminal labels, warning labels)

Step 5: Factory Acceptance Test (FAT)

Before shipment, the panel should undergo a Factory Acceptance Test (FAT) to verify that it meets the specification. A standard FAT for a control panel includes:

• Visual inspection: Component identification, label verification, wiring quality, cable management
• Insulation resistance test: Megger test between power circuits and earth (typically 1000V DC, minimum 1MΩ)
• Dielectric withstand test (hi-pot): Per IEC 61439-1, 2000V AC for 1 second between live parts and earth
• Functional test: Simulate all control inputs and verify correct output responses
• Communication test: Verify Modbus register values match the specification
• Protection relay test: Inject test currents to verify trip settings

For critical projects, arrange for a witness FAT where your engineer or a third-party inspector witnesses the testing at the factory.

Step 6: Documentation Package

A complete documentation package should be delivered with the panel:

• As-built wiring diagrams (updated to reflect any changes during manufacturing)
• Component data sheets and manuals
• Test reports (FAT results)
• CE declaration of conformity (if required)
• IEC 61439 verification report (if required)
• Modbus register map (if communication is included)
• Spare parts list

IEC 61439 Compliance

IEC 61439-1 (General rules) and IEC 61439-2 (Power switchgear and controlgear assemblies) are the primary standards for low-voltage switchgear and controlgear assemblies. Compliance requires:

• Design verification: Testing or calculation to verify temperature rise, short-circuit withstand, dielectric properties, and protection degree
• Routine verification: Tests performed on every assembly (insulation resistance, dielectric withstand, wiring check, operation check)
• Documentation: Verification report demonstrating compliance

For CE marking (required for equipment sold in Europe), the panel must comply with the Low Voltage Directive (LVD 2014/35/EU) and the EMC Directive (2014/30/EU). The manufacturer must issue a Declaration of Conformity and affix the CE mark.

Working with a Chinese Panel Manufacturer: Key Considerations

Component Authenticity

Specify acceptable component brands in writing and request component purchase invoices or certificates of authenticity for critical components (Siemens, Schneider, ABB, Mitsubishi, etc.). Counterfeit components are a real risk in the Chinese market.

Communication and Language

Ensure the manufacturer has English-language technical staff who can understand your specifications and respond to technical questions. Misunderstandings due to language barriers are a common source of errors in custom panel manufacturing.

Quality Management System

Verify that the manufacturer holds a current ISO 9001 certificate from an accredited certification body (Bureau Veritas, SGS, TÜV, etc.). Request a copy of the certificate and verify its validity on the certification body's website.

Lead Time

Typical lead times for custom panels from Chinese manufacturers:

• Standard control boxes (no PLC, simple wiring): 5–10 working days
• PLC control cabinets (with programming): 15–25 working days
• Complex MCC panels (multiple drawers, full documentation): 30–45 working days
• Add 5–10 days for CE certification documentation if required

Wanlong Electric OEM/ODM Services

Wanlong Electric provides complete OEM and ODM electrical panel manufacturing services for international customers:

• Complete Electrical Panel Design & Manufacturing Service — Full OEM/ODM from specification to delivery. English-language engineering support throughout.
• Supported panel types: LV switchgear (MNS, GCK, GGD), MCC panels, PLC control cabinets, motor control boxes, DC traction switchgear, prefabricated substations
• Standards: IEC 61439-1/2, IEC 60204-1, CE marking, CCC, ISO 9001
• Component brands: Siemens, Schneider Electric, ABB, Mitsubishi, Omron, Chint, Delixi (customer-specified brands accommodated)
• Enclosure materials: Cold-rolled steel, 304 stainless steel, 316 stainless steel
• IP ratings: IP30 to IP66
• Lead time: 7–45 working days depending on complexity
• MOQ: 1 unit (prototype orders accepted)

For a technical consultation or quotation, contact our engineering team. Please include your application description, electrical requirements, and target quantity. We respond within 24 hours with English-language support.

Related: PLC Control Box | MNS Low Voltage Switchgear | Air Circuit Breaker (ACB)