Phase-to-Phase and Phase-to-Earth Connections in Portable Earthing Sets: What Buyers Should Specify

A request such as:

Three-phase portable earthing set, 50 mm², 5 m.

is not enough for a reliable quotation.

The supplier still needs to know which conductors must be interconnected, how the assembly connects to earth, whether a common connecting cluster is required, the distance between phases, the distance to the earth point, the individual lead lengths, clamp interfaces, and the required short-circuit duty.

Phase-to-phase short-circuiting and phase-to-earth earthing are also not always two alternative product categories. A complete portable earthing arrangement may require both functions.

The key procurement question is therefore not:

Do I need a phase-to-phase set or a phase-to-earth set?

It is:

What connection topology does the approved earthing arrangement require, and does the offered equipment match that topology?

Follow local regulations and your site safety procedure.

Quick Answer: Define the Connection Arrangement Before the Product Configuration

For a multi-phase AC system, buyers should first define:

• Which conductors must be interconnected
• Whether phase-to-phase short-circuiting is required
• How the conductors connect to earth
• Whether the earth path is common or individual
• Whether a connecting cluster is required
• Phase spacing
• Distance to the earth point
• Phase-lead lengths
• Earth-lead length
• Line-clamp interfaces
• Earth-clamp interface
• Fault current
• Rated time
• Required test evidence

Only after this should the supplier decide how the requirement is packaged into a complete portable earthing set.

IEC 61230:2008 applies to portable equipment for temporary earthing or earthing and short-circuiting of electrically isolated or de-energized AC and DC installations. Its scope includes equipment containing an earthing device, a short-circuiting device, or a combined earthing-and-short-circuiting device.

For available system configurations, buyers can review our portable earthing and short-circuit kits.

Earthing and Short-Circuiting Are Different Functions

The terms should be separated before preparing an RFQ.

Phase-to-Phase Short-Circuiting

In a multi-phase arrangement, short-circuiting interconnects the conductors that the approved system requires to be bonded together.

From a purchasing perspective, buyers need to define:

• Number of conductors
• Phase spacing
• Number of branches
• Branch lengths
• Connecting cluster, if used
• Conductor cross-section
• Line clamps
• Complete short-circuit rating

Phase-to-Earth Earthing

The earthing part provides the required connection between the conductor arrangement and the approved earth or reference point.

Buyers should define:

• Earth-point type
• Earth-point geometry
• Distance to the earth point
• Number of earth paths
• Earth-lead length
• Earth-lead construction
• Earth clamp
• Complete rating

Combined Earthing and Short-Circuiting

Many portable sets combine the two functions.

The conductors may first be interconnected through phase leads or a cluster, with the assembly then connected to the designated earth point through an earth lead.

This is why “phase-to-phase vs phase-to-earth” should not automatically be treated as an either/or purchasing decision.

Connection Function Is Not the Same as Equipment Configuration

This distinction is particularly important because buyers may confuse:

• Phase-to-phase vs phase-to-earth
• Single-phase vs multi-phase equipment

They answer different questions.

A set can use individual single-phase devices while still forming an approved multi-conductor earthing arrangement.

A multi-phase device can also incorporate both short-circuiting and earthing functions.

Our guide to single-phase vs multi-phase portable earthing sets explains the equipment-configuration decision separately. The current page focuses on the electrical connection arrangement.

“Three-Phase Earthing Set” Is Not a Complete Specification

This is one of the most common RFQ problems.

A buyer writes:

3-phase earthing set.

But several different equipment arrangements could match that description.

For example, the project may require:

• Three phase branches connected to one cluster and one common earth lead
• Phase-to-phase short-circuiting plus a separate earth connection
• Three independent phase-to-earth leads
• A multi-phase assembly with different phase and earth-lead lengths
• Dedicated connection points built into the equipment

The supplier should not have to guess.

A better RFQ defines the topology with a drawing and individual lead information.

The tender should answer:

• Are all three phases bonded together?
• Is a cluster required?
• Is there one common earth lead?
• Are there individual earth leads?
• Where is the earth point?
• How far is it from the phases?
• What are the phase-to-phase distances?
• Which clamp fits each interface?

For a complete tender framework, see how to specify a portable earthing kit in a tender. The existing tender guide already treats application, fault duty, connection points, cable arrangement, and documentation as linked engineering inputs rather than independent product options.

What Buyers Should Specify for Phase-to-Phase Connections

The phase-to-phase part of the system should be defined by geometry, not just by the number of phases.

Useful RFQ inputs include:

• Number of phase conductors
• Center-to-center phase spacing
• Conductor or busbar geometry
• Clamp connection point
• Number of branch leads
• Individual branch lengths
• Connecting-cluster position
• Cable cross-section
• Cable material
• Clamp model or required jaw range
• Required fault-current duty
• Rated time
• Drawing reference

Phase spacing is especially important.

A portable assembly designed around 300 mm busbar spacing may not have suitable branch geometry for equipment with 1,000 mm or 1,500 mm spacing.

Do not ask the supplier only for:

Three phase leads, 1 m each.

Instead, provide actual dimensions from the equipment or approved design drawing.

What Buyers Should Specify for the Phase-to-Earth Path

The earth path should be treated as a separate engineering input.

Buyers should define:

• Earth-point location
• Earth-point material
• Connection geometry
• Distance from the conductor arrangement
• Required earth-lead length
• Cable cross-section
• Earth-clamp design
• Whether one common earth path or individual paths are required
• Fault-current requirement
• Identification and marking

This becomes important because the phase spacing and earth-point distance are rarely the same.

For example, the phase branches may each be relatively short while the earth point is several metres away.

One statement such as:

Cable length: 5 m

does not explain which cable is 5 m.

A clearer schedule might state separately:

• Phase A branch: ___ m
• Phase B branch: ___ m
• Phase C branch: ___ m
• Cluster-to-earth lead: ___ m

Lead lengths should come from the approved work geometry rather than a generic product catalogue.

For additional considerations around cable length, weight, slack, and electrical performance, see our portable earthing kit length selection guide. Excess cable length can add impedance, weight, storage difficulty, and handling problems, so more length should not automatically be treated as better.

Common Earth Path vs Individual Earth Paths

The RFQ should state whether the arrangement uses a common earth path or individual phase-to-earth paths.

Common Earth Path

A typical concept may be:

Phase conductors → branch leads → connecting cluster → earth lead → earth point

The buyer should define:

• Number of phase branches
• Cluster
• Earth lead
• Earth clamp
• Branch lengths
• Earth-lead length
• Complete rating

Individual Phase-to-Earth Paths

Another engineered arrangement may use separate earthing leads for individual conductors.

The buyer would then need to define:

• Number of leads
• Individual lead length
• Earth-point arrangement
• Clamp at each end
• Required ratings
• Identification

Neither arrangement should be selected simply because one has fewer components.

The approved topology should come from the system engineer, utility, employer procedure, or project specification.

What Does a Connecting Cluster Change?

A connecting cluster is not simply a convenient cable junction.

In a multi-phase portable earthing assembly, it may form part of the short-circuit current path and the transition to the earth lead.

Buyers should therefore confirm:

• Number of branch connections
• Cluster material
• Cluster design
• Cable interfaces
• Phase-lead cross-section
• Earth-lead interface
• Cluster identification
• Rated configuration
• Test-report coverage

If a test report includes one cluster design but the offered product uses another, the buyer should ask whether the new configuration is covered by the evidence.

The same principle applies to ferrules and cable terminations. Our grounding cable termination guide explains why ferrules, lugs, and clamp connections should be treated as parts of the current path rather than minor accessories.

Conceptual Connection Arrangements

The following examples are procurement concepts only. They are not installation instructions.

These examples do not tell a user which arrangement to apply in the field.

Application name alone does not determine the topology.

A substation, overhead line, switchgear installation, or industrial plant can use different approved arrangements depending on its system design, utility practices, fault duty, work method, and connection points.

Clamp Selection Depends on Both Paths

The phase clamp and earth clamp may have completely different interfaces.

A phase connection could involve:

• Round conductor
• Flat busbar
• Tubular busbar
• Dedicated ball stud
• Fixed earthing point

The earth connection may involve:

• Earth bar
• Grounding stud
• Structural connection point
• Dedicated earth terminal

Therefore, writing:

Grounding clamp included

is not sufficient.

The RFQ should identify the actual interface at both ends.

Our grounding clamp selection guide explains how buyers should match clamp geometry to round conductors, flat or tubular busbars, earth bars, ball studs, and other defined connection points.

Fault Duty Must Match the Actual Connection Arrangement

Once the topology is defined, the buyer should check whether the proposed assembly supports the required fault-current duty.

IEC 61230 is based on the electrodynamic and electrothermal effects of short-circuit current in portable earthing and short-circuiting equipment.

The important procurement question is not only:

Is the kit rated 25 kA for 1 second?

It is:

Was the relevant assembly configuration evaluated for the required rating?

Changing any of the following may affect the evidence review:

• Conductor cross-section
• Cable material
• Lead arrangement
• Connecting cluster
• Ferrules
• Phase clamps
• Earth clamp
• Cable length
• Number of branches

A rating printed in a catalogue should therefore be linked to the actual tested or technically supported configuration.

For a detailed explanation of current, rated time, peak factor, and evidence scope, see our portable earthing kit fault-current rating guide.

Test Evidence Should Match the Offered Drawing

One of the strongest RFQ requirements is:

Supplier shall provide a connection drawing identifying the offered assembly and the relevant test-evidence configuration.

A report review should check:

A report showing the correct kA value but a materially different assembly should trigger technical review.

This is also why type-test and delivery documents should not be treated as interchangeable. Our guide to IEC 61230 type tests vs routine tests explains the difference between design validation and delivery verification.

Ask for a Drawing, Not Only a Product Name

Two suppliers can both quote:

Three-phase portable earthing set

while offering very different assemblies.

One may supply:

• Three phase clamps
• Three branch leads
• One connecting cluster
• One earth lead
• One earth clamp

Another may supply:

• Three independent leads
• Three conductor clamps
• Separate earth connections
• No cluster

These should not be compared from the commercial product name alone.

A useful supplier drawing should identify:

• Phase clamps
• Earth clamp
• Phase leads
• Earth lead
• Connecting cluster
• Cable cross-sections
• Individual cable lengths
• Ferrules
• Connection IDs
• Assembly reference

The drawing becomes the bridge between:

RFQ → supplier quotation → test evidence → production → inspection

What Buyers Should Put in the RFQ

For complex projects, include a sketch or engineered connection diagram with the RFQ.

What Suppliers Should Return

A useful supplier technical submission should include:

• Proposed connection drawing
• Equipment configuration
• Number of phase clamps
• Number of earth clamps
• Number of phase leads
• Number of earth leads
• Connecting-cluster design
• Cable material
• Cable cross-sections
• Individual cable lengths
• Cable construction
• Ferrule design
• Clamp models
• Clamp jaw ranges
• Complete kit weight
• Rated current
• Rated time
• Peak-current basis
• IEC 61230 test reference
• Applicable drawing number
• Product marking
• Packing arrangement
• Technical deviations

This allows the buyer to compare complete configurations rather than generic product names.

Common Buyer Mistakes

Writing Only “Three-Phase Earthing Set”

The number of phases does not define the connection topology.

Treating Phase-to-Phase and Phase-to-Earth as Alternative Product Categories

A complete arrangement may require both short-circuiting and earthing functions.

Confusing Single-Phase Equipment with Phase-to-Earth Only

Single-phase describes equipment configuration. It does not automatically define the complete system topology.

Assuming Multi-Phase Equipment Always Uses One Earth Lead

The actual arrangement should be confirmed from the project specification and drawing.

Giving One Cable Length for the Entire Set

Phase branches and the earth lead may require different lengths.

Ignoring Phase Spacing

Incorrect branch geometry can make an otherwise suitable set incompatible with the actual equipment.

Ignoring the Earth-Point Interface

The earth clamp may need a completely different geometry from the phase clamps.

Approving a kA Rating Without Checking the Configuration

The test evidence should be connected to the offered assembly.

Comparing Products Without Drawings

The same commercial name may describe different connection arrangements.

Asking the Supplier to Define the Site Earthing Philosophy

The supplier can configure equipment to a requirement. The approved earthing arrangement should come from the responsible engineering and site-safety framework.

How We Review a Portable Earthing Arrangement Inquiry

When we receive an inquiry, we review the topology before finalizing the equipment configuration.

We Confirm the Required Function

We identify whether the project requires earthing, short-circuiting, or a combined arrangement.

We Identify Which Conductors Must Be Connected

We confirm the number of conductors and required phase-to-phase relationship.

We Confirm the Earth Path

We identify whether the project requires a common or individual earth path.

We Review the Connecting Cluster

Where a cluster is required, we confirm its position, branch interfaces, and relationship to the earth lead.

We Confirm Phase Spacing

Actual equipment dimensions are used to define branch geometry.

We Confirm the Earth-Point Distance

The earth lead is specified separately from the phase branches.

We Match Clamps to Each Interface

Phase clamps and earth clamps are selected from the actual connection points rather than from voltage alone.

We Review Cable Lengths Separately

Each branch and earth lead is checked against the project geometry.

We Compare the Drawing with Fault-Current Evidence

The proposed assembly should be supported by the relevant current, time, and configuration evidence.

We Declare Configuration Deviations

Any difference from the RFQ or approved drawing should be identified before production.

For substation projects, these decisions should be coordinated with the actual busbar, feeder, transformer, and earth-point interfaces. See our substation electrical safety solutions for broader application context. The current substation page also identifies portable earthing equipment as part of the station safety equipment system.

FAQ

Is phase-to-phase short-circuiting the same as phase-to-earth earthing?

No. Phase-to-phase short-circuiting interconnects the required conductors. Phase-to-earth earthing provides the required path to the designated earth or reference point.

Does a complete portable earthing set need both functions?

It depends on the approved arrangement. IEC 61230 covers earthing devices, short-circuiting devices, and combined earthing-and-short-circuiting equipment.

Is a three-phase earthing set always three phase leads plus one earth lead?

No. The product name does not define the complete topology. Buyers should review the connection drawing.

Is phase-to-earth the same as single-phase equipment?

No. Single-phase and multi-phase describe equipment configuration. Phase-to-earth describes the electrical connection function. See our single-phase vs multi-phase guide for the separate configuration decision.

Can individual phase-to-earth leads replace an integrated multi-phase assembly?

This should only be defined through the approved engineering arrangement and supported equipment rating. It should not be treated as a field substitution based on product availability.

Do phase leads and the earth lead need the same length?

Not necessarily. Their lengths should be based on the actual conductor spacing and distance to the earth point.

Do all leads have to use the same cross-section?

Do not assume this from the product name. The required conductor designs must follow the project engineering, fault duty, applicable standard, and supported assembly configuration.

Does changing the connection arrangement affect the fault-current evidence?

It can affect the evidence review because the current path may involve different leads, clusters, ferrules, clamps, or lengths. Buyers should verify that the report covers the proposed configuration.

What information should buyers send with an RFQ?

Send the connection arrangement, number of conductors, phase spacing, earth-point distance, individual lead lengths, clamp interfaces, fault current, rated time, applicable standard, and preferably a connection drawing.

Practical Buyer Summary

Do not purchase a portable earthing set from the words:

Three-phase grounding set.

Instead, define:

• Which conductors need short-circuiting
• How the assembly connects to earth
• Common or individual earth paths
• Connecting-cluster requirement
• Phase spacing
• Earth-point distance
• Individual phase-lead lengths
• Earth-lead length
• Phase-clamp interfaces
• Earth-clamp interface
• Cable cross-section
• Fault current
• Rated time
• Test-evidence configuration
• Connection drawing

The most important distinction is:

Phase-to-phase and phase-to-earth describe connection functions. Single-phase and multi-phase describe equipment configurations.

A strong procurement process should connect:

Required conductors → phase-to-phase bonding → earth path → cable geometry → clamps and interfaces → fault duty → tested drawing → supplier approval

Once the connection topology is defined, buyers can then decide whether an integrated multi-phase assembly or another approved equipment configuration best fits the project.

For the next step, review our portable earthing and short-circuiting kit range and use the connection drawing, fault-duty requirement, lead lengths, and clamp interfaces as the basis for quotation.

Follow local regulations and your site safety procedure.