Panel Technical Specification: Standard Custom LV Panel Guide
A practical model panel technical specification for custom LV panels, covering electrical ratings, enclosure construction, busbars, protection, internal wiring, testing, documentation
A panel technical specification defines the electrical, mechanical, protection, construction, testing and documentation requirements for a custom LV panel before manufacture. For LV assemblies within its scope, IEC 61439 provides the framework for specifying and verifying the assembly rather than relying on a generic “LV panel” description.
A custom electrical panel should not be specified only by its current rating and number of outgoing circuits.
The specification should establish what the manufacturer is expected to supply, how the assembly is to be constructed, what performance it must achieve, and what evidence must be provided before delivery.
This is particularly important for consultants, contractors and procurement teams comparing panel manufacturers.
Paneltech Systems Ltd. provides LV panels and electrical solutions for industrial, commercial and infrastructure applications in Kenya and the wider East African region.
What Is a Panel Technical Specification?
A panel technical specification is a project document that defines the minimum requirements for an electrical panel or switchboard. It translates the electrical design into measurable requirements that manufacturers can use for engineering, manufacturing, testing and documentation.
A good specification should answer questions such as:
- What voltage will the panel operate at?
- What current must it carry?
- What is the prospective short-circuit current?
- What protection devices are required?
- What enclosure rating is needed?
- What internal separation is required?
- What metering is required?
- How will cables enter the panel?
- What testing is required?
- What drawings must the manufacturer submit?
The specification should work together with:
- Single-line diagrams
- Load schedules
- Panel schedules
- Cable schedules
- Protection studies
- Equipment schedules
- Architectural drawings
- Mechanical schedules
The panel manufacturer should not be expected to infer critical requirements that can be defined by the project engineer.
Model Technical Specification for Custom LV Panels
The following model specification can be adapted for custom LV panels used in commercial, industrial and infrastructure projects. Replace bracketed values with project-specific engineering information before issuing the document for tender or manufacture.
1. General Requirements
Supply, manufacture, assemble, test, deliver and commission custom low-voltage switchboards/panels complete with all equipment, protection devices, busbars, wiring, terminals, labels, metering, accessories and documentation necessary for a complete and operational installation.
The assembly shall be suitable for the electrical system and environmental conditions stated in the project drawings and schedules.
The manufacturer shall provide technical drawings for review and approval before commencing manufacture.
The specification should make clear whether the contractor is responsible for:
- Design
- Manufacture
- Supply
- Installation
- Testing
- Commissioning
IEC 61439 and LV Assembly Requirements
IEC 61439 establishes requirements and verification principles for low-voltage switchgear and controlgear assemblies within its scope. A specification should identify the applicable part of the IEC 61439 series and require the assembly to meet the relevant requirements.
The specification can state:
The LV assembly shall comply with the applicable requirements of the IEC 61439 series appropriate to the assembly application. The manufacturer shall provide evidence of the required design verification and routine verification in accordance with the applicable standard.
The exact applicable standard should be confirmed by the electrical engineer.
Depending on the application, consideration may include:
- IEC 61439-1 — General rules
- IEC 61439-2 — Power switchgear and controlgear assemblies
The specification should not simply state “IEC 61439 certified” without identifying what compliance evidence is required.
For procurement purposes, the consultant can request:
- Design verification evidence
- Routine verification records
- Manufacturer documentation
- Component data
- Test documentation
Electrical Ratings
The panel technical specification should clearly state rated voltage, frequency, current and short-circuit requirements. These values should come from the project's electrical calculations and system design.
Model Clause
The assembly shall be rated for the system voltage, frequency and continuous current specified in the project electrical schedules. The assembly shall be capable of withstanding the prospective short-circuit conditions applicable at its installation point.
A specification schedule can include:
| Parameter | Project Requirement |
|---|---|
| Rated operational voltage | [Insert V] |
| Rated insulation voltage | [Insert V] |
| Frequency | [Insert Hz] |
| Rated current | [Insert A] |
| Short-circuit withstand | [Insert kA] |
| Number of phases | [Insert] |
| Neutral arrangement | [Insert] |
| Earthing system | [Insert] |
Do not use generic ratings where project calculations are available.
Main Incomer Specification
The main incomer should be selected according to the calculated maximum demand, fault level and protection strategy. The specification should identify the required breaker type, rating and adjustment or protection functions.
Model Clause
The main incoming circuit breaker shall be suitably rated for the maximum demand and prospective fault current at the installation point. The breaker shall incorporate the required overload and short-circuit protection functions and shall be coordinated with downstream protective devices.
Depending on the panel, the incomer may be:
- ACB
- MCCB
- MCB
- Switch-fuse
- Isolator
Large LV switchboards may require adjustable protection settings and communication facilities.
Outgoing Feeder Specification
Each outgoing feeder should be specified according to its connected load, cable rating, fault level and protection requirements. Breaker ratings should be coordinated with the cables and downstream equipment.
Model Clause
Provide outgoing feeders as indicated on the approved single-line diagram and panel schedule. Each feeder shall be equipped with a suitably rated protective device and termination facilities appropriate to the specified outgoing cable.
The schedule should identify:
- Feeder reference
- Description
- Breaker type
- Breaker rating
- Breaking capacity
- Cable size
- Load
- Phase
- Spare capacity
Busbar Specification
Busbars must be sized for continuous current and applicable short-circuit conditions. The panel technical specification should define the required material, arrangement, neutral and earth configuration and applicable verification requirements.
Model Clause
The assembly shall incorporate suitably rated copper busbars designed for the specified continuous current and short-circuit conditions. Busbars shall be adequately supported, insulated or shrouded where required and arranged to provide appropriate clearances and creepage distances.
The specification can also identify:
- Phase busbars
- Neutral busbar
- Earth bar
- Busbar supports
- Busbar insulation
- Jointing requirements
- Identification
The final busbar dimensions should be determined by the manufacturer in accordance with the applicable design and verification requirements.
Enclosure Construction
The enclosure should provide suitable mechanical protection and environmental resistance for the installation location. Material, thickness, finish, access and cable-entry arrangements should be defined in the specification.
Model Clause
The panel enclosure shall be constructed from suitably robust materials appropriate to the installation environment and shall be finished to provide adequate corrosion and mechanical protection.
The specification may define:
- Mild steel
- Stainless steel
- Powder coating
- Paint finish
- Sheet thickness
- Door construction
- Hinges
- Locks
- Mounting plates
- Gland plates
The correct material depends on the installation environment.
For example, a coastal or corrosive environment may require more stringent corrosion protection than a clean indoor electrical room.
IP Rating
The required IP rating should be selected according to the panel's actual installation environment. Indoor electrical rooms, dusty factories and outdoor installations may require different levels of ingress protection.
Model Clause
The completed enclosure shall provide a minimum ingress protection rating of IP[insert rating] appropriate to the installation environment and project requirements.
Consider:
- Dust
- Water
- Humidity
- Condensation
- Outdoor exposure
- Cleaning methods
- Industrial contamination
An IP rating describes protection against ingress under defined test conditions; it should not be treated as a substitute for corrosion or thermal design.
Internal Separation
Where internal separation is required, the specification should clearly state the intended arrangement between busbars, functional units and cable termination areas. This can support safer access and improved maintainability where appropriate.
Model Clause
The assembly shall incorporate internal separation as specified in the project requirements, providing appropriate segregation between busbars, functional units and cable termination areas.
The required form of separation should be determined by the consultant based on:
- Safety
- Maintenance
- Operational continuity
- Panel configuration
- Project requirements
Protection Devices
Protective devices should be selected and coordinated to protect cables, equipment and the electrical system against applicable fault conditions. The specification should require appropriate protection performance rather than merely specifying breaker sizes.
Protection may include:
- Overload protection
- Short-circuit protection
- Earth-fault protection
- Motor overload protection
- Undervoltage protection
- Overvoltage protection
- Surge protection
For larger installations, protection settings should be coordinated with the project's protection study.
Metering Requirements
Metering requirements should be stated in the panel specification so that the manufacturer includes the required instruments, CTs, displays and communication interfaces.
Model Clause
Provide digital multifunction metering equipment where indicated, including suitable current transformers, voltage connections, protection and communication interfaces.
Depending on the project, the meter may display:
- Voltage
- Current
- Frequency
- Active power
- Reactive power
- Apparent power
- Energy
- Power factor
Where remote monitoring is required, the specification should identify the required communication interface.
Surge Protection
Surge protection should be coordinated with the installation's earthing, lightning protection and distribution arrangement. The panel specification should state where surge protective devices are required and what system they are intended to protect.
Model Clause
Provide surge protective devices at locations indicated on the approved electrical design, complete with suitable upstream protective devices, connection conductors and status indication.
The final SPD arrangement should be determined from the project's electrical and lightning-protection design.
Earthing and Bonding
Every custom LV panel should have appropriate protective-earthing and bonding provisions. The specification should require a dedicated earth bar and effective bonding of exposed conductive parts.
Model Clause
Provide a suitably rated copper earth bar throughout the assembly. The enclosure, doors, gland plates and other exposed conductive parts shall be effectively bonded in accordance with the applicable electrical installation requirements.
The final earthing system must follow the project's approved electrical design.
Cable Entry and Termination
Cable-entry requirements affect the panel's physical construction, gland plates, internal clearances and termination space. These requirements should be specified before fabrication.
Model Clause
Provide suitable cable-entry arrangements for all incoming and outgoing cables shown on the approved cable schedule. Provide removable gland plates, cable supports and adequate termination space.
Specify where applicable:
- Top entry
- Bottom entry
- Side entry
- Cable trench entry
- Gland plates
- Busduct entry
- Armoured cable termination
Internal Wiring
Internal wiring should be properly sized, routed, identified and terminated to facilitate safe operation, testing and maintenance. Control and power wiring should be appropriately segregated where required.
Model Clause
Internal wiring shall be neatly routed and securely supported. Conductors shall be suitably rated for their intended application and shall be identified at both ends. Control wiring shall be terminated on suitably numbered terminal blocks.
The specification can also require:
- Ferrules
- Wire markers
- Terminal numbering
- Wire ducts
- Control fuses
- Segregation
- Spare terminals
Control Panel Requirements
Custom control panels should be specified around the process-control requirements rather than only the electrical load. PLCs, HMIs, relays, sensors, interlocks and communication interfaces should be identified where required.
Model Clause
Provide a complete control system incorporating PLC, HMI, relays, contactors, terminal blocks, indication, control switches and communication interfaces as indicated on the approved control philosophy and drawings.
The panel may interface with:
- Motors
- Pumps
- VFDs
- Sensors
- Valves
- SCADA
- Building management systems
- Energy-management systems
APFC Panel Requirements
An APFC panel should be specified according to the required reactive-power correction, capacitor-stage arrangement and power-quality conditions. Harmonic-producing loads should be assessed before finalising capacitor equipment.
Model Clause
Provide an automatic power-factor correction panel of the capacity specified in the project electrical schedule, complete with APFC controller, capacitor stages, switching devices, protection and required accessories.
Paneltech Systems provides APFC panel solutions for suitable applications.
Where significant nonlinear loads exist, the specification should address harmonic mitigation.
VFD Panel Requirements
VFD-based panels require coordination between the drive, motor, incoming protection, bypass arrangements, control system and ventilation. The specification should identify the required drive functions and interfaces.
Model Clause
Provide variable-frequency drives suitably rated for the connected motors and application, complete with required input protection, output connections, control interfaces, local indication and accessories.
Paneltech Systems provides VFD drive solutions for variable-speed motor applications.
Generator and ATS Integration
Where the panel interfaces with a generator, the technical specification should define the incoming sources, transfer method, interlocking and control requirements. Automatic transfer systems should be coordinated with the generator controller and load priorities.
Model Clause
Where indicated, provide an automatic mains/generator transfer arrangement complete with source monitoring, electrical and mechanical interlocking, generator start signal, adjustable transfer delays and required indication.
For smaller installations, a manual transfer arrangement may be specified where appropriate.
Factory Testing and Routine Verification
Factory testing verifies that the completed assembly has been constructed correctly and operates as intended before delivery. The specification should make testing a contractual requirement and identify the documentation expected.
Model Clause
The completed assembly shall undergo applicable routine verification and testing before dispatch. Test results shall be recorded and submitted to the consultant/client as part of the equipment documentation.
Testing may include:
- Visual inspection
- Mechanical inspection
- Wiring verification
- Protective conductor continuity
- Insulation verification where applicable
- Functional testing
- Interlock testing
- Metering verification
- Protection verification
The exact verification programme should follow the applicable standard and project requirements.
Factory Acceptance Testing
For critical or complex panels, a factory acceptance test can allow the consultant or client to review the assembly before shipment. The FAT scope should be agreed before manufacturing is completed.
Model Clause
Where specified, the manufacturer shall provide facilities for factory acceptance testing by the consultant/client or their appointed representative. The FAT shall be conducted against an agreed test procedure and approved drawings.
The FAT may verify:
- Component identification
- Wiring
- Control logic
- Interlocks
- Metering
- Alarm functions
- Communication
- Protection functions
Site Installation and Commissioning
Site commissioning confirms that the panel has been installed correctly and interfaces properly with the wider electrical system. It should include verification of field connections and operational functions.
Model Clause
Following installation, the panel shall be inspected, tested and commissioned by competent personnel. Site testing shall verify power connections, control wiring, earthing, protection, interlocks, metering and operational functions as applicable.
Commissioning records should be submitted to the client.
Documentation Requirements
A complete technical specification should make drawings, certificates and test records mandatory deliverables. The final documentation should reflect the equipment actually manufactured and installed.
Required Documentation
The manufacturer should provide, as applicable:
- General arrangement drawings
- Single-line diagrams
- Wiring diagrams
- Control schematics
- Component schedules
- Terminal schedules
- Cable-entry details
- Protection settings
- Datasheets
- Test certificates
- Routine verification records
- FAT records where applicable
- Operation and maintenance information
- As-built drawings
For larger projects, documentation should be submitted progressively for review.
Panel Technical Specification Table
A technical specification schedule gives the manufacturer a concise summary of the panel's required electrical and mechanical characteristics. The values below should be replaced with project-specific requirements.
| Parameter | Specification |
|---|---|
| Panel Type | Custom LV switchboard |
| Rated Voltage | [Insert V] |
| Rated Frequency | [Insert Hz] |
| Rated Current | [Insert A] |
| Short-Circuit Rating | [Insert kA] |
| Main Incomer | ACB/MCCB as specified |
| Busbar Material | Copper / as specified |
| Busbar Rating | [Insert A] |
| Neutral | Full/reduced rating as designed |
| Earth Bar | Copper |
| Enclosure Material | As specified |
| IP Rating | [Insert IP rating] |
| Internal Separation | As specified |
| Cable Entry | Top / bottom / side |
| Metering | As specified |
| SPD | As required |
| APFC | Where required |
| VFDs | Where required |
| ATS/MTS | Where required |
| Control System | As specified |
| Testing | Factory and site |
| Documentation | Complete technical package |
| Standard | Applicable IEC 61439 requirements |
Technical Submittals Before Manufacture
The manufacturer should submit technical information for review before fabrication begins. This gives the consultant an opportunity to verify ratings, dimensions, components and interfaces against the approved design.
A typical submittal package may include:
- General arrangement
- Single-line diagram
- Panel dimensions
- Component schedule
- Breaker datasheets
- Busbar details
- Protection information
- Metering details
- Cable-entry arrangement
- Terminal schedule
- Control schematic
- Heat-dissipation considerations where applicable
- Compliance information
- Testing procedure
Manufacturing should proceed according to the approved documentation.
How to Specify Custom Panels Without Over-Specifying
A good specification establishes measurable performance requirements without unnecessarily restricting technically equivalent solutions. Consultants should specify what the panel must achieve while allowing compliant engineering solutions where appropriate.
Avoid clauses such as:
Panel shall be exactly 800 mm wide.
unless the project genuinely requires that dimension.
Instead, specify the required:
- Electrical ratings
- Functional requirements
- Environmental conditions
- IP rating
- Internal separation
- Protection
- Standards
- Testing
- Documentation
- Space constraints
The manufacturer can then develop a suitable physical arrangement within the project constraints.
How to Prevent Non-Compliant Panel Substitutions
Tender documents should require bidders to declare deviations and demonstrate technical equivalence for proposed alternatives. A lower-cost component should not automatically be accepted if it changes the required performance.
Model Clause
Any proposed deviation from the specified equipment, components, construction or performance requirements shall be clearly identified in the tender submission. Alternatives shall not be incorporated without prior technical review and written approval.
Request:
- Manufacturer datasheets
- Technical schedules
- Compliance statements
- Test evidence
- Product references
- Deviation schedules
This creates a clearer basis for technical tender evaluation.
Custom Panel Specification Checklist
Before issuing a panel specification, consultants should verify the electrical ratings, enclosure requirements, protection, construction, testing and documentation. A checklist reduces the risk of missing critical procurement requirements.
Use this checklist:
- Panel type identified
- System voltage confirmed
- Frequency confirmed
- Rated current confirmed
- Fault level confirmed
- Main incomer specified
- Outgoing feeders listed
- Busbar requirements defined
- Enclosure requirements defined
- IP rating specified
- Internal separation specified
- Cable entry defined
- Earthing requirements defined
- Metering requirements defined
- SPD requirements reviewed
- APFC requirements reviewed
- VFD requirements reviewed
- ATS/MTS requirements reviewed
- Control requirements defined
- Testing requirements included
- FAT requirements included where applicable
- Documentation requirements included
- Applicable standards identified
- Deviations/substitutions clause included
Download the Standard Panel Specification Asset
This model specification can be converted into a consultant-ready document for tendering, procurement and technical review. Project-specific electrical ratings and requirements should be completed before the document is issued.
The asset can be structured into:
Section 1 — General Requirements
Section 2 — Applicable Standards
Section 3 — Electrical Ratings
Section 4 — Enclosure and Construction
Section 5 — Busbars and Connections
Section 6 — Protection and Control
Section 7 — Metering and Communication
Section 8 — Testing and Verification
Section 9 — Documentation
Section 10 — Installation and Commissioning
This structure gives consultants and procurement teams a reusable panel technical specification framework for custom LV panels.
For additional engineering resources, visit the Paneltech Systems Knowledge Centre.
Contact Paneltech Systems Ltd
Powering Kenya's Future with Reliable Electrical Solutions
Email: [email protected]
Phone: 0799 531765
Location: Nairobi, Kenya
Website: Paneltech Systems Ltd
Our Specialized Services
- Low Voltage (LV) Panels & APFC Panels
- VFD Drive Solutions & ATS / MTS Systems
- Solar Power & EV Charging Infrastructure
- Electrical Supplies & Engineering Consultations
For a custom panel technical specification, LV switchboard design or project-specific panel quotation, contact Paneltech Systems Ltd to discuss the electrical ratings, protection, enclosure, testing and documentation requirements for your project.
