How to Specify a Portable Earthing Kit in a Tender: Engineering Inputs Buyers Should Provide

We often receive inquiries that only state the system voltage and required quantity.

For example:

We need ten portable earthing kits for a 33 kV system.

This is not enough to prepare a reliable technical offer.

A portable earthing and short-circuiting kit must match the application, approved fault-current duty, protection clearing time, connection points, lead arrangement, cable lengths, clamps, access conditions, operating tools, standards, marking, and acceptance documents.

Without these inputs, different suppliers may quote different assemblies under the same tender item. The prices may look comparable, but the technical scope may not be the same.

In this guide, we explain what engineers should define before procurement issues the tender, what suppliers should declare in their offers, and how buyers can compare technical responses before comparing price.

Follow local regulations and your site safety procedure.

Quick Answer: Define the Duty, Interface, and Configuration First

A portable earthing kit tender should define four things before asking for a quotation:

1. What electrical duty the set must withstand
2. Where and how the set will connect
3. What complete configuration the project requires
4. How compliance and delivery will be verified

Voltage class alone is not a complete specification.

The engineer should provide the application, electrical system, approved fault current, clearing time, work location, connection-point details, required lead arrangement, access conditions, applicable standard, and acceptance criteria.

The supplier should then declare the proposed cables, clamps, operating poles, ratings, materials, drawings, test evidence, markings, packing, and any technical deviations.

This division of responsibility makes quotations easier to compare and reduces technical changes after the order is placed.

Why “Portable Earthing Kit for 33 kV” Is Not a Complete Specification

A voltage level tells us something about the electrical installation. It does not define the complete portable earthing set.

The description below is too weak:

Supply portable earthing kit for 33 kV.

It does not answer the following questions:

• Is the kit for a substation, switchgear room, overhead line, underground cable system, railway system, or industrial plant?
• Is the system AC or DC?
• What is the approved short-circuit current?
• What is the protection clearing time?
• Where will the temporary earthing connection be made?
• Does the set connect to a conductor, busbar, ball stud, earth bar, fixed terminal, or another interface?
• What clamp opening and contact geometry are required?
• How many phase leads are required?
• Is the arrangement phase-to-phase, phase-to-earth, clustered, or based on individual leads?
• What cable lengths are needed?
• Is an insulating operating pole required?
• What standard and test evidence must be supplied?
• Does the project require serial numbers, kit IDs, or QR-based asset records?
• What accessories and storage case are included?

When these details are missing, each supplier must make assumptions.

One supplier may quote three separate leads. Another may quote a cluster arrangement. One may include an operating pole and storage case. Another may exclude them. Cable lengths, cross-sections, clamp types, ratings, and document packages may also differ.

The result is not a fair technical or commercial comparison.

Engineering Inputs Required Before Procurement Issues the Tender

Before preparing the tender, the project team should separate engineering decisions from supplier proposals.

The following table provides a practical starting point.

A supplier can propose a configuration after receiving these inputs.

However, the supplier should not invent the project fault current, clearing time, connection geometry, or acceptance criteria.

Define the Application and Actual Work Location

The first question we ask is:

Where will the kit be used?

A portable earthing kit for an outdoor substation may need different clamps, cable lengths, accessories, and operating poles from a kit used inside compact switchgear.

The application may include:

• Outdoor substations
• Indoor switchgear
• Motor control centers
• Overhead distribution lines
• Transmission lines
• Underground cable systems
• Railway or traction systems
• Generating stations
• Industrial electrical installations

The tender should also define the actual work point.

For example, “substation use” is still broad. The temporary earthing connection may be required at:

• A tubular busbar
• A flat busbar
• A conductor
• A transformer connection
• A feeder terminal
• A fixed grounding stud
• An earth bar
• A dedicated temporary earthing point

Each interface may require a different clamp design.

Our guide comparing substation, overhead-line, and underground-cable applications explains why one portable kit should not automatically be treated as universal across different work environments.

In the tender, the application should be specific enough for the supplier to prepare the correct assembly drawing and component list.

Fault Current and Clearing Time Must Come from Engineering

Voltage class is not the same as short-circuit duty.

Two systems with the same nominal voltage may have different available fault currents and protection clearing times. The portable earthing set must be reviewed against the approved project duty, not against a general voltage label.

IEC 61230 applies to portable equipment used for temporary earthing or earthing and short-circuiting on electrically isolated or de-energized AC and DC installations and networks. It expresses withstand capability using rated current, rated time, and peak factor. It does not assign a rated voltage to the complete equipment, although equipment dimensions remain related to the installation voltage.

Therefore, the engineer should provide:

• Approved short-circuit current
• Required current duration
• Relevant peak-current requirement
• Protection clearing time
• Project or utility design reference
• Any required safety factor or local acceptance rule

We ask buyers to provide these approved values.

We should not estimate them from the voltage level alone. A supplier can help match the proposed assembly to the stated duty, but the supplier should not replace the system study or project engineer.

The tender should also define what evidence is required to support the supplier’s rating claim. This may include a test report, type-test reference, compliance statement, or another project-approved document.

For a detailed explanation of the standard and its procurement meaning, buyers can review our guide to IEC 61230 compliance for portable earthing equipment.

Define Every Connection Point and Clamp Interface

A portable earthing set is only useful when its clamps match the actual connection points.

The term “universal clamp” is not a complete engineering specification.

The tender should define the connection interface using dimensions, drawings, approved equipment data, or clear technical descriptions.

Useful inputs may include:

• Conductor material
• Conductor diameter
• Flat busbar width
• Busbar thickness
• Tubular busbar diameter
• Ball-stud diameter
• Earth-bar dimensions
• Terminal shape
• Contact-surface condition
• Required clamp opening
• Installation angle
• Available space around the connection point
• Obstructions or barriers
• Required adapter or fixed connection point

Photographs can help reduce misunderstanding, but photographs should not replace dimensions when clamp fit depends on geometry.

For switchgear and panel projects, restricted access may be as important as clamp opening. A technically suitable clamp may still be difficult to position if the cabinet depth, door opening, internal barrier, or clamp angle has not been considered.

Our guide to portable earthing for switchgear and panels provides more detail on interface and access control.

In the tender, ask the supplier to provide:

• Clamp model
• Clamp drawing
• Jaw range
• Contact-face design
• Connection method
• Material
• Rated duty
• Operating-pole interface
• Proposed adapter, if required

This allows the engineer to approve the physical interface before production.

Define the Required Lead Arrangement

The tender should describe the portable earthing kit as an assembly, not as unrelated cables and clamps.

The required arrangement may include:

• Individual phase leads
• Phase-to-phase leads
• Phase-to-earth lead
• Cluster or star-point arrangement
• Common connecting point
• Branch leads
• A separate earth lead
• Multiple parallel leads where approved
• Separate sets for different work positions

The engineer should define or approve:

• Number of phases
• Number of cables
• General arrangement
• Branch lengths
• Earth-lead length
• Required connection sequence identification
• Required color identification
• Whether the set must remain together as one asset
• Whether components may be replaced individually

The supplier should return an assembly drawing showing the proposed layout.

This is important because two quotations with the same number of clamps and the same total cable length may still represent different configurations.

For a clearer description of the full supply scope, see our guide to complete portable earthing kit components.

Cable Inputs Engineers Should Provide

Cable selection should not begin with one question only:

What cable cross-section do you offer?

The project team should provide or approve the inputs that control the cable proposal.

These may include:

• Approved fault-current duty
• Clearing time
• Required cable lengths
• Approved cable route
• Required or preferred cross-section
• Conductor material
• Flexible cable requirement
• Sheath or insulation requirement
• Color
• Environmental exposure
• Minimum bending or handling expectations
• Termination requirement
• Storage and transport limits

The supplier should declare:

• Conductor material
• Actual conductor cross-section
• Cable construction
• Number and type of strands
• Overall diameter
• Sheath or insulation material
• Supplied length
• Termination method
• Ferrule or end-fitting type
• Assembly rating
• Supporting test evidence

Cable length must be treated carefully.

A longer cable is not automatically better. It may improve reach, but it also changes handling, storage, routing, weight, impedance, and the complete assembly design.

The tender should define the required connection distances or an approved length range. It should not simply ask for the longest available cable.

Our article on portable earthing lead selection factors explains why fault duty, clearing time, cross-section, length, flexibility, terminations, and clamp compatibility must be considered together.

Define Operating-Pole and Access Requirements

The tender should state whether the kit requires an insulating operating pole.

It should describe the access condition rather than leaving the supplier to guess the field method.

Useful inputs include:

• Indoor or outdoor use
• Ground-level or elevated connection
• Cabinet or open conductor
• Fixed or telescopic pole requirement
• Required transport length
• Required storage length
• Interface-head requirement
• Clamp operating mechanism
• Space restriction
• Carrying method
• Required pole bag or case

The tender should not create its own safe working distance unless this has been approved by the project procedure.

Instead, it should state the required access condition and ask the supplier to declare the proposed pole type, working length, collapsed length, interface, and relevant documents.

The approved operating distance and work method should follow the project design and site procedure.

Define the Complete Supply Scope

Many tender disputes come from unclear supply boundaries.

One bidder may include a full assembly. Another may quote only cables and clamps.

The tender should clearly state whether the supply includes:

• Phase clamps
• Earth clamp
• Copper leads
• Ferrules
• Lugs or end fittings
• Common connecting point
• Cluster connection
• Adapters
• Insulating operating pole
• Pole heads
• Storage bag or case
• Component labels
• Kit identification label
• Inspection record
• User documentation
• Spare clamps
• Spare fittings
• Cleaning or storage accessories
• Assembly drawing
• Test and compliance documents

A “kit” should not be considered complete only because several parts are packed in one bag.

The components, ratings, interfaces, markings, documents, and carrying system should match the approved application.

Separate Engineer-Defined and Supplier-Declared Information

A strong tender does not require the engineer to design every manufacturing detail.

It also does not leave critical project decisions to the supplier.

The responsibilities should be separated clearly.

Engineer-Defined Mandatory Inputs

The engineer should define:

• Application
• Electrical system
• Voltage class
• Approved fault current
• Clearing time
• Work location
• Connection interfaces
• Required lead arrangement
• Access limits
• Applicable standard
• Acceptance criteria
• Required documents
• Site-specific restrictions

Supplier-Declared Technical Information

The supplier should declare:

• Proposed configuration
• Cable cross-section
• Cable construction
• Actual cable lengths
• Clamp models
• Clamp jaw ranges
• Clamp and connector materials
• Ferrule and termination design
• Operating-pole type
• Assembly rating
• Test-report references
• Marking system
• Packing method
• Inspection and storage information

Optional or Custom Inputs

The buyer may also define:

• Cable color
• Customer logo
• Multilingual labels
• Asset numbers
• QR codes
• Storage-bag format
• Spare components
• Custom packing
• Site or department codes

This structure keeps engineering responsibility clear.

The engineer defines the required duty and interfaces. The supplier declares how the proposed equipment meets them.

Portable Earthing Kit Technical Data Schedule

A technical data schedule helps procurement compare offers line by line.

This table should be completed before price comparison.

Otherwise, a lower price may simply reflect shorter cables, different clamps, fewer accessories, lower document coverage, or excluded operating poles.

Require a Technical Compliance and Deviation Schedule

Every bidder should respond to each technical requirement.

A useful response format includes:

• Comply
• Partially comply
• Alternative offered
• Not applicable
• Deviation
• Supporting document reference

General statements are not enough.

Examples of weak supplier responses include:

• Standard model
• Suitable for 33 kV
• As per customer requirement
• Equivalent
• High-quality copper cable
• Universal clamp
• IEC standard

These statements do not show whether the proposed assembly matches the tender.

We recommend asking suppliers to identify every deviation and reference the related datasheet, drawing, test report, or technical note.

A technical deviation should be reviewed before the commercial offer is accepted.

Documents Suppliers Should Return with the Tender

The tender should state whether documents are required:

• With the bid
• After technical approval
• Before production
• Before shipment
• With the delivered equipment

This prevents document requirements from being discussed only after the product has been manufactured.

Marking and Traceability Requirements

Portable earthing sets should remain identifiable after delivery.

The tender may require:

• Kit ID
• Serial number
• Batch number
• Cable identification
• Clamp identification
• Rated-current information
• Rated-time information
• Standard reference
• Manufacturing date
• Customer asset number
• Site code
• QR code
• Inspection status field

The tender should also define whether identification is required only at kit level or on major individual components.

For multi-site utilities and contractors, component-level identification can help prevent cables, clamps, poles, and bags from being mixed between sets.

Our guide to identification and traceability for portable earthing sets explains how serial numbers, labels, QR codes, and records can support asset management.

Define Delivery Acceptance Before Production

A good tender does not stop after supplier selection.

It also defines how the delivered set will be checked.

Delivery acceptance may include confirmation that:

• The supplied configuration matches the approved drawing
• Cable quantities match the technical schedule
• Cable lengths match the approved values
• Cable cross-sections match the approved proposal
• Clamps match the approved interface drawings
• Operating poles and adapters are included
• Ferrules and end fittings match the approved design
• Labels are readable
• Kit IDs match the documents
• Test evidence refers to the supplied model or assembly
• The component list is complete
• The storage case is included
• Spare components are included
• Packing is suitable for the agreed transport method
• All deviations were approved before production

We prefer to resolve configuration, marking, documentation, and packing requirements before production.

This reduces disputes during receiving inspection and project handover.

Weak Tender vs Better Tender

Weak Tender Description

Supply portable earthing kit for 33 kV.

This description does not define the electrical duty, interfaces, complete configuration, documents, or acceptance criteria.

Better Tender Description

Supply a portable earthing and short-circuiting set for a 33 kV outdoor substation. The proposed set shall match the engineer-approved fault-current duty and clearing time. It shall be suitable for the identified busbar and earth-bar connection points. The bidder shall provide an assembly drawing, cable data, clamp interface details, operating-pole information, standard and test-document references, identification markings, technical deviations, component list, and packing details.

This is still only an RFQ wording example. It is not a complete engineering specification.

The project engineer must add the actual fault duty, connection dimensions, required configuration, site constraints, and acceptance criteria.

Common Portable Earthing Kit Tender Mistakes

Specifying Voltage Level Only

Voltage class does not define fault duty, clearing time, clamp interface, cable arrangement, or access.

The tender should include the actual engineering inputs.

Leaving Fault Current and Clearing Time Blank

The supplier should not guess these values.

They should come from the project engineer, approved system study, utility data, or other accepted design information.

Not Defining the Actual Application

A portable earthing kit for switchgear may differ from one used on an overhead line or outdoor busbar.

The tender should state the work environment and actual connection point.

Failing to Provide Interface Dimensions

A clamp can have the correct electrical rating but still be physically incompatible.

Provide drawings, dimensions, or approved interface details.

Treating Components as Independent Items

Cables, clamps, ferrules, connectors, and operating poles should be evaluated as one assembly.

A strong cable does not correct an unsuitable clamp or weak termination.

Requesting IEC 61230 Without Defining the Required Evidence

A standard reference alone does not explain which report, declaration, marking, or document the buyer expects.

The tender should state the required evidence.

Using One Line Item for Different Applications

Substation, overhead-line, switchgear, and underground-cable sets may require different configurations.

Separate line items are clearer when interfaces or applications differ.

Comparing Price Before Technical Deviations

A lower price may be based on a different scope.

Complete the technical comparison and deviation review first.

Asking for Documents After Production

Test, marking, traceability, and certificate requirements should be agreed before production.

Late requests can cause delay or document mismatch.

How We Review a Portable Earthing Tender Inquiry

When we receive a tender inquiry, we review it in a fixed order.

We Confirm the Application

We first identify the site, equipment, and intended work point.

We Review the Approved Fault Duty

We ask for the approved short-circuit current, clearing time, and any peak requirement.

We Check the Connection Interfaces

We review conductor, busbar, earth-bar, stud, terminal, or other connection-point details.

We Review the Lead Arrangement

We confirm the number of leads, branch arrangement, earth lead, cable lengths, and connection layout.

We Match Clamps, Cables, and Operating Poles

We treat these items as one proposed assembly.

We Prepare an Assembly Proposal

Where required, we provide a drawing and component schedule for technical approval.

We Identify Technical Deviations

We explain where the proposed product differs from the tender.

We Confirm Documents and Markings

We confirm the datasheet, test evidence, compliance statement, labels, serial numbers, and traceability.

We Confirm Packing and Delivery Scope

We check the storage case, accessories, spare parts, labels, and packing list.

This process allows the buyer to review one complete technical proposal instead of a list of disconnected components.

FAQ

Is voltage class enough to specify a portable earthing kit?

No. Voltage class does not define the available fault current, clearing time, connection interfaces, cable arrangement, cable length, clamps, operating poles, documents, or acceptance criteria.

Who should provide the fault current and clearing time?

These values should come from the project engineer, approved system study, utility data, protection design, or another accepted engineering source. The supplier should not guess them from the voltage level.

Should the engineer specify the cable cross-section?

If the project has already approved a cross-section, it should be included in the tender. If suppliers are allowed to propose one, the tender should provide the approved fault duty and require supporting technical evidence and engineering approval.

Why are connection-point drawings needed?

They help the supplier match the clamp opening, contact face, geometry, angle, and access condition. Photographs can support the review, but dimensions are often still required.

Can one tender specification cover substations and overhead lines?

Only when the engineering duty, interfaces, configuration, and access conditions are genuinely the same. In many projects, separate line items are clearer and easier to evaluate.

What documents should suppliers submit with the tender?

The document package may include a technical datasheet, assembly drawing, component list, cable data, clamp drawing, operating-pole data, test evidence, compliance statement, marking sample, packing details, and technical deviation schedule.

Should every component have a serial number?

Not always. The project may use one kit-level ID or combine a main kit ID with component-level markings. The tender should state the required traceability level.

When should technical deviations be reviewed?

They should be reviewed before the commercial offer is accepted and before production begins. An unapproved deviation can affect rating, interface fit, supply scope, documentation, or delivery acceptance.

Practical Buyer Summary

A reliable portable earthing kit tender cannot be prepared from voltage level and quantity alone.

The engineering team should define:

• Application
• Electrical system
• Fault current
• Clearing time
• Work location
• Connection interfaces
• Lead arrangement
• Cable distances
• Access conditions
• Applicable standard
• Documents
• Traceability
• Acceptance requirements

The supplier should declare:

• Proposed assembly
• Cable construction and size
• Cable lengths
• Clamp models and interfaces
• Operating poles
• Ratings
• Test evidence
• Marking
• Packing
• Technical deviations

Procurement should compare completed technical schedules before comparing price.

The final tender should create a clear path from engineering input to supplier proposal, technical approval, production, delivery inspection, and asset registration.

For project sourcing, buyers can also review our portable earthing and short-circuiting kits after the required engineering inputs have been confirmed.

Follow local regulations and your site safety procedure.