LT Panel Technical Specification & RFQ Guide

An LT panel technical specification is the document that fixes, before pricing, the electrical system data, assembly rated current, prospective short-circuit level, busbar requirement, form of internal separation, enclosure and IP requirement, feeder schedule, protection philosophy, metering and communication scope, cable termination arrangement, applicable standards and testing scope. Define those items and every bidder is quoting substantially the same panel.

Whatever the RFQ leaves undefined, the manufacturer will define on your behalf — usually in the cheapest way that is still technically defensible. A blank fault level or an unstated form of separation is not a minor omission: it changes breaker selection, busbar cross-section, panel dimensions and price, and it is normally discovered after the order.

Why LT Panel RFQs Go Wrong

An LT panel quotation is only as accurate as the information given to the panel manufacturer.

That sounds obvious, but in real projects, many RFQs still arrive with only a single-line diagram, feeder ratings and a note saying, “Panel shall be suitable for 415 V, 50 Hz.” The manufacturer is then expected to assume the fault level, busbar material, form of separation, enclosure protection, cable entry, breaker configuration, metering, communication requirements and even site conditions.

That is where trouble begins.

Two manufacturers may quote against the same RFQ but make completely different technical assumptions. The lower quotation may simply exclude something the other manufacturer has included.

A good LT panel specification removes those assumptions.

This guide explains what an engineer, consultant, EPC contractor or purchase team should define before requesting a quotation for a PCC, MCC, PMCC or other low-voltage switchboard.

What Should an LT Panel RFQ Contain?

At minimum, a good LT panel RFQ should clearly define:

Electrical system parameters
Panel application and configuration
Rated current
Prospective short-circuit level
Busbar requirements
Incomer and outgoing feeder details
Protection philosophy
Metering and communication
Internal separation
Enclosure and IP protection
Site and environmental conditions
Cable entry and termination requirements
Applicable standards
Testing and inspection requirements
Drawings and documentation
Spare feeders and future expansion

The purpose is not to make the specification unnecessarily complicated.

The purpose is to ensure that every bidder is pricing substantially the same technical requirement.

1. Start With the Electrical System — Not the Panel Size

Before deciding the panel dimensions, breaker brand or enclosure thickness, define the electrical system to which the panel will be connected.

The RFQ should state:

Parameter	Example*
System voltage	415 V AC
Number of phases	3 Phase
System configuration	3 Phase, 4 Wire
Frequency	50 Hz
Earthing system	TN-S / TN-C-S / TT / as applicable
Transformer rating	1600 kVA
Transformer impedance	6.25%
Number of transformers/sources	1 / 2 / Multiple
DG connection	Yes / No
Solar/BESS connection	Yes / No
Neutral arrangement	Full-size / reduced / project-specific

\*Values above are examples only. Actual values must come from the project electrical design.

Why is this information important?

Because the electrical source determines much more than the incoming current.

It influences:

Fault current
Breaker interrupting requirements
Busbar withstand requirement
Neutral loading
Protection coordination
Earthing arrangement
Interlocking philosophy
Source changeover logic

If two transformers, DG sets or other sources can operate in parallel, that operating condition must also be stated.

Do not expect the panel manufacturer to guess it.

2. Define the Panel's Actual Duty

“LT Panel” is a broad description.

The RFQ should clearly state what the assembly is expected to do.

For example:

PCC — Power Control Center

Generally used for main power reception and distribution to downstream MCCs, utility feeders, large loads and distribution boards.

MCC — Motor Control Center

Primarily used for controlling and protecting motors through DOL, star-delta, soft starter, VFD or other starter configurations.

PMCC — Power & Motor Control Center

Combines power distribution and motor-control functions in one assembly.

APFC Panel

Provides automatic reactive-power compensation based on the system's actual power-factor requirements.

VFD Panel

Integrates variable-frequency drives with suitable switching, protection, cooling, bypass and harmonic-management provisions as required.

DG Synchronization / AMF Panel

Manages generator operation, synchronization, load sharing, mains failure or source transfer according to the project philosophy.

Defining the application at the beginning prevents the specification from becoming a generic list of components.

3. Specify Rated Current Correctly

The panel incomer rating should not be selected simply because a certain ACB rating is commercially available.

The engineer should consider:

Maximum operating load
Diversity and demand
Transformer or generator capacity
Continuous loading
Future expansion
Ambient temperature
Harmonic loading where relevant
Arrangement of circuits inside the enclosure

For example, a project may require an 2500 A incomer while the selected breaker frame has a higher maximum rating. Those are not necessarily the same thing.

The specification should distinguish between:

Breaker frame size
Breaker rated current
Long-time protection setting
Assembly rated current
Main busbar rating

IEC 61439 deals with the design, construction and verification requirements of low-voltage switchgear and controlgear assemblies, while IEC 61439-2 applies specifically to power switchgear and controlgear assemblies. cite

4. Do Not Leave the Short-Circuit Rating Blank

This is one of the most important parameters in an LT panel RFQ.

A specification should clearly define the required prospective short-circuit current at the panel location.

Depending on the requirement, relevant values may include:

Short-circuit current in kA RMS
Short-time withstand current, Icw
Duration, such as 1 second
Peak withstand current, where applicable
Breaker breaking capacity

These ratings are not interchangeable.

For example, the breaking capacity of an MCCB or ACB and the short-time withstand capability of the complete busbar/assembly address different aspects of fault performance.

Circuit-breakers used in low-voltage systems fall under IEC 60947-2, while the assembly itself is addressed through IEC 61439. cite

Where Should the Fault Level Come From?

Preferably from the project short-circuit study.

If a study is not yet available, the designer should determine an appropriate design value using the transformer/source data, upstream network strength, conductor impedance, parallel sources and relevant system contribution.

A common transformer-only approximation is sometimes used during preliminary design, but it should not replace a proper short-circuit assessment when multiple sources, generators or large rotating machines are involved.

On a 1600 kVA transformer at 6.25% impedance and 415 V, the full-load current is approximately 2226 A, so the transformer-only symmetrical fault contribution works out to roughly 35 kA. Add a strong upstream network, a second transformer running in parallel, or a large connected motor load in a chemical or pharma plant, and the actual prospective current at the busbar can sit meaningfully above that figure. This is the item we push back on at clarification stage, because a panel verified for 35 kA and a panel verified for 50 kA are different assemblies — different busbar section, different supports, different breaker series — and no amount of commercial negotiation changes that after despatch. The design value must come from the project short-circuit study.

Bad RFQ

“Breaker shall be suitable for fault current.”

Better RFQ

“Main LT assembly shall be designed for the project fault level stated in the approved electrical study. Breaker interrupting ratings and assembly short-circuit withstand ratings shall meet or exceed the applicable design requirement.”

The second version leaves far less room for commercial interpretation.

5. Define the Busbar — Don't Just Write 'Copper Busbar'

A busbar specification should cover more than material.

Consider defining:

Copper or aluminium
Main busbar rated current
Neutral busbar requirement
Earth busbar requirement
Short-circuit withstand
Phase identification
Jointing arrangement
Surface treatment where required
Busbar chamber arrangement
Future extension provision
Temperature-rise compliance
Busbar support and insulation system

The appropriate busbar arrangement depends on current, short-circuit forces, enclosure configuration, ambient conditions and the verified assembly design.

That is why specifying only a cross-sectional area such as “2 × 100 × 10 mm copper” can be unnecessarily restrictive unless the project engineer has a specific design reason.

A performance-based requirement is often stronger:

“Busbar system shall be sized and verified for the specified continuous current, temperature-rise limits and short-circuit withstand requirement.”

It tells the manufacturer what the system must achieve without forcing an arbitrary design.

6. Define the Incomer Properly

For the main incomer, specify at least:

ACB / MCCB / switch disconnector as applicable
Number of poles
Fixed or draw-out construction
Rated current
Breaking capacity
Protection release type
Required protection functions
Electrical or manual operation
Closing coil
Shunt trip
Under-voltage release, if required
Auxiliary contacts
Spring charging motor
Interlocks
Communication requirement
Source identification
Bus coupler arrangement, if applicable

If the panel contains two incomers and a bus coupler, the RFQ should also explain the operating philosophy.

For example:

Can both incomers run in parallel?

Is the bus coupler normally open or normally closed?

Is mechanical/electrical interlocking required?

Is automatic source transfer required?

Is synchronization permitted?

These questions change the design significantly.

7. Prepare a Proper Outgoing Feeder Schedule

The feeder schedule is one of the most valuable documents in an RFQ.

Instead of writing only:

“10 Nos. MCCB feeders”

provide information such as:

Feeder	Load	Rating	Breaker/Starter	Poles	Control	Remarks
F1	MCC-1	400 A	MCCB	4P	Manual	—
F2	HVAC	250 A	MCCB	4P	Manual	—
F3	Pump-1	30 kW	DOL	—	Local/Remote	Running
F4	Pump-2	30 kW	DOL	—	Local/Remote	Standby
F5	Process Motor	45 kW	VFD	—	PLC	Modbus
F6	Spare	250 A	MCCB	4P	—	Future

For motor feeders, add:

Motor kW
Full-load current if known
Starter type
Duty
Local/remote operation
Emergency-stop philosophy
PLC interface
Number of starts per hour if relevant
Field push-button station requirement
Cable size where available

A detailed feeder schedule dramatically reduces clarification cycles.

8. Define the Protection Philosophy

A specification should tell the panel builder what protection is required, but protection settings should ideally be coordinated with the electrical system.

Depending on the application, protection may include:

Overload
Short circuit
Instantaneous overcurrent
Earth fault
Under/over-voltage
Phase failure
Phase sequence
Motor thermal protection
Locked rotor / stall
Differential or other specialised protection
Reverse power for generation applications

For electronic trip units, specify required functions instead of simply requesting “microprocessor release.”

Two microprocessor releases can have very different capabilities.

Where selectivity is important, ask for:

Protection coordination
Time-current coordination
Breaker discrimination/selectivity
Settings schedule

The manufacturer's breaker selection should ultimately work with the project's protection philosophy—not against it.

9. Metering: Decide What You Actually Need

An RFQ often specifies “digital multifunction meter” without stating what information needs to be measured or communicated.

Define whether you require:

Voltage
Current
Frequency
Power factor
kW
kVA
kVAr
Energy
Demand
Harmonics
Individual feeder metering
Main incomer only
Communication to PLC/SCADA/BMS/EMS

Also define the communication protocol where integration is required.

Examples may include:

Modbus RTU
Modbus TCP
Ethernet-based communication
Other project-specific industrial protocols

CT ratios, accuracy class and burden should be coordinated with the actual metering and protection requirements.

10. Define Form of Internal Separation

For many industrial projects, simply specifying enclosure IP rating is not enough.

The RFQ should also define whether internal separation is required.

IEC 61439-2 addresses forms of internal separation within power switchgear and controlgear assemblies. The current edition also contains requirements relating to protection of live parts when forms higher than Form 1 are used. cite

Depending on project philosophy, the requirement may be:

Form 1
Form 2
Form 3
Form 4

Higher separation can improve segregation between busbars, functional units and terminals, but it also affects:

Panel dimensions
Cost
Cable accessibility
Heat dissipation
Maintenance philosophy

Therefore, avoid automatically specifying the highest form for every application.

Select it based on operational and maintenance needs.

11. Specify the Enclosure and IP Rating Based on the Site

Ask a simple question:

Where will this panel actually operate?

Inside an air-conditioned electrical room?

Inside a dusty production facility?

Near a process area?

Outdoor?

High humidity?

Corrosive environment?

Then specify:

Indoor / outdoor
Floor-mounted / wall-mounted
Single-front / double-front
Required IP degree
Ambient temperature
Relative humidity
Altitude if relevant
Pollution/corrosion conditions
Ventilation requirement
Space-heater requirement
Anti-condensation requirement
Canopy requirement for outdoor installation
Material of construction
Paint system / colour where required

An IP rating should solve an environmental requirement, not simply be copied from an old project specification.

12. Cable Entry and Termination Are Part of the Panel Design

A technically correct panel can still create major site problems if cable information is missing.

The RFQ should state:

Bottom or top cable entry
Incoming cable or busduct
Number of runs
Cable size
Copper/aluminium conductor
Single-core/multicore
Required gland plate
Cable alley requirement
Termination space
Neutral termination
Earth termination

For larger feeders, physical termination space can become a major design constraint.

Do not wait until manufacturing is complete to discover that six runs of large single-core cables cannot comfortably terminate at the breaker.

We have opened panels at site where a 2500 A aluminium incomer needed six to eight large single-core runs per phase, and the cable alley had been sized from a drawing that showed only "incoming cable." The bending radius alone made two of those runs impossible to dress without straining the terminals. Our recommendation: state the conductor material, number of runs per phase and cross-section in the RFQ, even approximately, because cable alley depth is decided at the GA stage and cannot be added later.

13. Specify Spare Feeders and Future Expansion Separately

There is an important difference between:

Spare feeder

and

Space for future feeder.

A spare feeder may include the complete breaker, metering, wiring and termination arrangement.

Future space may only reserve physical room for later addition.

Similarly, future busbar extension should be stated separately.

A useful RFQ might specify:

20% spare equipped feeders
20% future space
Main busbar sized for defined future load
Provision for future extension on one side of the panel

Do not simply write “20% spare.”

Explain what that 20% means.

14. Mention the Correct Standards

The applicable standards should be selected based on the project, equipment and destination.

For many industrial low-voltage power switchgear assemblies, the IEC 61439 series forms a key technical basis.

IEC 61439-1:2020 defines general rules covering service conditions, construction requirements, technical characteristics and verification requirements. IEC 61439-2:2020 provides specific requirements for power switchgear and controlgear assemblies up to 1,000 V AC or 1,500 V DC. cite

Individual components may have their own applicable standards—for example, IEC 60947-2 applies to low-voltage circuit-breakers within its scope. cite

A project specification should therefore avoid the vague phrase:

“Panel shall comply with all IEC standards.”

Instead, list applicable standards and project specifications deliberately.

15. Ask for Design Verification — Not Just a Certificate

This is an area where buyers should be particularly careful.

Modern IEC 61439 terminology focuses on design verification and routine verification of the assembly.

A quotation saying “IEC 61439 compliant” is not, by itself, enough information to understand what has actually been verified.

During technical evaluation, consider asking:

Which assembly system/design is being offered?
What design-verification evidence applies?
Does the offered configuration remain within the verified design rules?
What short-circuit rating has been verified?
What current/temperature-rise configuration has been verified?
What IP degree is supported?
What routine verifications will be performed on the supplied assembly?
What documentation will be submitted?

This is a much stronger approach than accepting a certificate without checking its relevance to the proposed panel.

16. Define Factory Acceptance Testing Before the Order

FAT requirements should be included in the RFQ—not introduced after the panel has been manufactured.

Depending on the project, the FAT scope may include:

Visual and workmanship inspection
Dimensional verification
Verification against approved GA
Wiring inspection
Component verification against BOM
Mechanical operation
Electrical interlocks
Control logic
Protection functions
Metering
Communication
Indication and annunciation
Insulation/dielectric checks as applicable
Functional simulation
Routine verification records
Client/consultant witness points

If PLC, VFD, synchronization or automation logic is included, clearly define what will be simulated during FAT.

A useful FAT proves that the panel behaves according to the approved philosophy—not merely that the lamps illuminate.

In our in-house FAT experience, hardware rarely fails at this stage. What fails is logic that was never written down: a bus coupler interlock the consultant assumed and the RFQ never stated, an emergency-stop that was expected to trip the incomer rather than only the starter, or a PLC interlock between two pumps that appeared for the first time in a witness engineer's question. Our recommendation: attach the control and interlock philosophy to the RFQ as a separate write-up, and list in advance which sequences will be simulated during FAT. We support customer-witnessed FAT and third-party inspection, and the witnessed tests that go smoothly are always the ones where the test schedule was agreed before manufacturing started.

17. Define the Documentation You Expect

Documentation should be part of the commercial scope.

Typical project documentation may include:

General Arrangement drawing
Single-Line Diagram
Power wiring diagrams
Control schematics
Terminal plans
Bill of Materials
Component datasheets
Busbar details
Protection settings
Interlock philosophy
PLC I/O list where applicable
Communication architecture
Design-verification documentation where applicable
Routine verification / test reports
FAT reports
As-built drawings
Operation and maintenance manuals

Specify:

Submission stage
Number of revision cycles
Approval requirement
Final as-built format

This avoids disputes at project completion.

A Practical LT Panel RFQ Checklist

Before sending your RFQ, check whether the following information is available:

Electrical System

✓ System voltage ✓ Frequency ✓ Number of phases and wires ✓ Earthing system ✓ Transformer/source data ✓ Fault level ✓ DG / solar / BESS interface if any

Panel

✓ Panel type ✓ Indoor/outdoor ✓ Rated current ✓ Short-circuit withstand requirement ✓ IP rating ✓ Form of separation ✓ Single-front/double-front ✓ Busbar material ✓ Cable entry

Switchgear

✓ Incomer rating ✓ Breaker type ✓ Number of poles ✓ Breaking capacity ✓ Protection functions ✓ Fixed/draw-out requirement ✓ Bus coupler philosophy

Outgoing Feeders

✓ Complete feeder schedule ✓ Load description ✓ Ratings ✓ Motor starter type ✓ Spare feeders ✓ Future space

Controls

✓ Metering ✓ PLC interface ✓ SCADA/BMS/EMS requirement ✓ Communication protocol ✓ Remote/local control ✓ Interlocks

Project Requirements

✓ Applicable standards ✓ Approved component makes, if mandatory ✓ Drawings required ✓ FAT scope ✓ Inspection requirements ✓ Documentation ✓ Delivery schedule

If several of these items are missing, expecting a technically comparable quotation from multiple panel builders becomes difficult.

Common Mistakes When Preparing an LT Panel RFQ

Mistake 1: Selecting the lowest quotation without normalising the technical scope

A lower price may result from different assumptions, exclusions or ratings.

Prepare a technical comparison before commercial comparison.

Mistake 2: Not specifying the fault level

This can directly affect breaker selection, busbar system and assembly design.

Mistake 3: Specifying only breaker ampere rating

Current rating alone does not define the breaker's protection or fault capability.

Mistake 4: Copying an old project specification

Site conditions, transformer sizes, load characteristics and project philosophies change.

Specifications should too.

Mistake 5: Overspecifying everything

Higher IP, higher Form, larger busbar, premium breaker series and extensive metering do not automatically create a better engineering solution.

Good engineering means appropriate specification, not maximum specification.

Mistake 6: Ignoring cable termination

Many practical panel problems happen at site, not in the drawing office.

Mistake 7: Asking for “IEC 61439 compliant” without checking the offered assembly

Always understand what design and verification evidence actually applies to the configuration being supplied.

What Should a Good Panel Manufacturer Return With the Offer?

A technically useful quotation should ideally make the manufacturer's assumptions transparent.

Ask the bidder to provide:

Technical datasheet
Compliance statement
Deviation list
Preliminary GA, where possible
Proposed switchgear makes and series
Busbar material and rating
Fault withstand details
IP and Form of separation
Metering and communication scope
List of included accessories
Design-verification information
FAT/testing scope
Documentation list
Delivery period
Explicit exclusions

The deviation list is particularly important.

A bidder should not silently substitute a requirement.

If there is a technical deviation, it should be visible before the order is placed.

Example: A Better Way to Write an LT Panel RFQ

Instead of:

“Supply 2500 A LT PCC panel with ACB incomer and MCCB outgoings.”

write something closer to:

“Design, manufacture, assemble, test and supply indoor LT PCC assembly for the project electrical distribution system. The assembly shall be designed for the specified system voltage, frequency, fault level, service conditions and approved SLD. Main busbar rating, short-circuit withstand, enclosure protection, internal separation, incomer/outgoing switchgear, metering, protection, cable termination and future extension provisions shall comply with the approved project datasheet and applicable IEC 61439 requirements. Bidder shall submit technical datasheet, deviations, GA, component details, applicable design-verification evidence and proposed FAT/routine verification documentation with the offer or during the agreed document cycle.”

Then attach the project-specific datasheet and feeder schedule.

That one step can eliminate a significant amount of ambiguity.

Why This Matters Beyond Getting a Better Price

A well-prepared specification improves more than procurement.

It helps:

Consultants

Evaluate different manufacturers on a common technical basis.

EPC Contractors

Reduce technical queries, drawing revisions and procurement delays.

Purchase Teams

Compare quotations more fairly.

Project Engineers

Ensure the supplied equipment matches the system design.

Maintenance Teams

Receive a panel that is easier to operate, expand and maintain.

Panel Manufacturers

Engineer the correct solution from the first proposal instead of pricing assumptions.

In other words, a good RFQ creates a better project for both buyer and manufacturer.

How Wisdom Techno Solutions Approaches LT Panel Requirements

At Wisdom Techno Solutions, we manufacture and engineer a broad range of low-voltage power distribution and control assemblies including PCC, MCC, PMCC, iMCC, APFC, VFD and DG synchronization panels.

Wisdom Techno Solutions is a licensed partner for three design-verified switchgear platforms: Rittal Ri4Power (Rittal Solutions Partner since 2021 — the Ri4Power system carries Intertek ASTA design verification to IEC 61439-1 and -2 Edition 3, with copper and aluminium busbar systems up to 6300 A), C&S CX (Licensed Partner since 2023, up to Form 4B Type II) and Siemens SIEPAN Elite/8PU (IEC 61439 Solutions Partner since 2024). We build to each system's verified configuration and routine-verify every assembly in-house at our Vadodara, Gujarat facility, for industrial, EPC and infrastructure projects across India. That places the specified fault level, busbar rating and form of separation inside a verified design envelope.

Our existing product range includes custom PCC solutions and IEC 61439-based panel systems for industrial and infrastructure applications.

More importantly, our engineering approach starts with understanding the electrical system and project requirement—not simply selecting components from an SLD.

For a project enquiry, sharing the following information helps our engineering team prepare a substantially more accurate technical and commercial proposal:

SLD
Load/feeder schedule
System voltage and frequency
Transformer/source information
Fault level
Preferred switchgear makes, if any
Panel location and IP requirement
Form of separation
Cable details
Control/interlock philosophy
Metering and communication requirements
Applicable project specification
FAT/inspection requirements

If every detail is not yet available, the missing parameters can be identified during the technical discussion rather than being hidden as assumptions in the quotation.

Conclusion

The best LT panel RFQ is not necessarily the longest one.

It is the one that clearly defines the parameters that affect safety, performance, maintainability and price.

Start with the electrical system.

Define the fault level.

Prepare the feeder schedule.

Clarify the busbar, breaker, protection, enclosure, cable and control requirements.

Specify the applicable standards and verification requirements.

And most importantly, make every bidder state their assumptions and deviations.

When that is done correctly, quotation comparison becomes easier, engineering revisions reduce and the final panel has a much better chance of matching the actual project requirement.

Planning an LT panel, PCC, MCC or PMCC project?

Share your SLD and technical requirements with Wisdom Techno Solutions for an engineering review and project-specific panel proposal.

Related Guides

Frequently Asked Questions (FAQs)

1. What information is required for an LT panel quotation?

At minimum, provide the SLD, system voltage and frequency, assembly rated current, source/transformer details, prospective fault level, feeder schedule, panel location, IP requirement, form of separation, busbar preference, breaker requirements, cable entry details and applicable project standards. The feeder schedule and the fault level do most of the work, because together they fix the panel's physical size, busbar section and switchgear selection. If any of these are still open, state them as "to be confirmed" rather than leaving them blank — a stated gap gets clarified, while a blank gets assumed.

2. What is the standard for LT panels?

For many industrial power switchgear assemblies, IEC 61439-1 and IEC 61439-2 are key reference standards. Individual components such as circuit-breakers are covered by their applicable product standards, including IEC 60947-2 for circuit-breakers within its scope.

3. How is the short-circuit rating of an LT panel selected?

It should be based on the prospective short-circuit current at the panel location and the project protection/system study. Source impedance, transformers, cables, parallel sources and other system contributions may affect the available fault current.

4. What is the difference between breaker breaking capacity and panel short-circuit withstand?

Breaker breaking capacity relates to the breaker's ability to interrupt a specified fault current, while assembly short-circuit withstand addresses the ability of the switchboard busbar system, supports and enclosure to withstand fault-related thermal and mechanical stresses for a specified duration. The two are verified differently: breaking capacity belongs to the component under IEC 60947-2, and short-time withstand current Icw belongs to the assembly under IEC 61439-2. A panel fitted with a breaker of adequate breaking capacity can still be inadequate if the busbar system has not been verified for the same fault level and duration. This is why an RFQ should state both the required breaker interrupting rating and the required assembly withstand, typically for 1 second.

5. Should I specify copper or aluminium busbars?

Both can be engineered successfully. Selection should consider current rating, physical size, joints, thermal performance, short-circuit withstand, project standards, lifecycle requirements and economics rather than material name alone.

6. Which Form of separation should I choose for an LT panel?

The required Form should be selected according to the project's segregation, maintenance and operational requirements. Specifying a higher Form without a functional need can increase size and cost.

7. What documents should I ask for from an LT panel manufacturer?

Typical documents include the General Arrangement drawing, single-line diagram, power and control schematics, bill of materials, component datasheets, terminal plans, busbar details, design-verification and routine-verification documentation, FAT reports, protection settings where applicable, and final as-built drawings with the O&M manual. The commercial scope should also fix the submission stage, the number of revision cycles and who approves each document. Documentation left undefined is the most common cause of disputes at project closeout, because the drawings that matter for maintenance are the as-built ones and those are produced last.

8. Why should the fault level be included in the RFQ?

Because short-circuit requirements affect breaker selection, busbar withstand, supports, clearances and the overall assembly design. Leaving the fault level undefined forces the manufacturer to make assumptions.

9. What is the difference between a spare feeder and future space?

A spare feeder normally includes installed functional equipment, while future space reserves physical room for equipment to be added later. The RFQ should state exactly which is required.

10. Can a panel manufacturer prepare the specification from an SLD?

A manufacturer can help develop the requirement, but an SLD alone may not contain all necessary project parameters. Fault level, environmental conditions, operational philosophy, cable details, protection requirements and documentation expectations may still need to be confirmed.

LT Panel Specification

How to Prepare an LT Panel Technical Specification & RFQ: Complete Guide for Industrial Projects