Select an MCB busbar in this order: identify every connected device; verify its busbar terminal and choose pin, fork, or another supported interface; confirm pitch and contact dimensions; map poles and phase sequence across the complete lineup; select cross-section and ratings from documented project conditions; calculate teeth/modules and length; then specify end treatment, accessories, market, quantity, and sample approval.
MCB busbar selection worksheet
Use this worksheet before choosing a catalogue reference or sending a request for quotation (RFQ).
| Selection stage | Required input | Specification output | Stop point |
|---|---|---|---|
| 1. Device lineup | Manufacturer, exact models, types, poles, quantities, auxiliaries | Controlled left-to-right device schedule | Stop if any connected device is unidentified |
| 2. Terminal interface | Approved connection side, terminal type, drawing, photo, or sample | Pin, fork, alternative interface, or confirmation required | Stop if the busbar connection position is unclear |
| 3. Contact and pitch | Terminal centers, contact width/length, clamp position | Contact geometry and center-to-center pitch | Stop if only nominal module width is known |
| 4. Pole and sequence | Circuit arrangement, L1/L2/L3/N pattern, mixed devices | Pole count and repeated phase/neutral sequence | Stop if the physical lineup and circuit sequence disagree |
| 5. Electrical data | System voltage, design current, protective device, feed arrangement, applicable evidence | Product-specific cross-section and rating requirement | Stop if current suitability is inferred from cross-section alone |
| 6. Modules and length | Device widths, auxiliaries, tooth count, usable panel space | Required contacts and overall/finished length | Stop if modification or end treatment is undefined |
| 7. Complete assembly | Feed connector, end caps, covers, unused contacts, marking | Accessory and finishing bill of materials | Stop if exposed or unused positions are unresolved |
| 8. Approval and supply | Target market, quantity, documentation, sample plan | Approved model/drawing and repeat-order reference | Stop before volume order if fit is unverified |
This order matters. Choosing a cross-section or nominal pole count before verifying the terminal can produce a busbar that is electrically plausible but physically unusable.
Step 1: Define the complete protective-device lineup
List every device the busbar must connect from left to right. Record:
Manufacturer and full model reference
Device type: miniature circuit breaker (MCB), residual current circuit breaker (RCCB), residual current circuit breaker with overcurrent protection (RCBO), isolator, or another modular device
Pole configuration for each device
Quantity and physical order
Side-mounted auxiliary contacts, releases, or spacers
Intended incoming feed point
Top or bottom connection, where the device provides a defined choice
Do not reduce a mixed lineup to “twelve MCB modules” if it also contains an RCCB, RCBO, isolator, or auxiliary. Different device widths and terminal patterns can interrupt a repeated busbar sequence.
Official selection guidance in the ABB modular busbar catalogue explicitly separates terminal type, number of poles, device type, combinations, conductor size, and number of modules. Treating these as independent inputs is a sound starting point for any brand or supplier review.
Specification output: a left-to-right schedule such as `RCCB 4P + MCB 1P × 9`, with every exact device reference and auxiliary shown.
Step 2: Verify the busbar terminal interface
The device terminal controls whether a pin, fork, or another contact system can be considered. Check the device datasheet and accessory documentation for:
The terminal intended for a busbar connection
Whether a cable and busbar use separate or shared clamping paths
Supported pin, fork, blade, or dedicated accessory form
Terminal opening and clamp geometry
Contact insertion direction
Connection side
Restrictions created by adjacent devices or accessories
A visible screw does not prove that a fork busbar is supported. A rectangular opening does not prove that every pin busbar will fit. When the documentation does not show the contact path clearly, request the terminal drawing or use a physical sample.
The pin type vs fork type busbar guide provides the focused interface decision matrix. Its key rule is simple: neither format is universally better; use the one explicitly supported by the exact terminal.
Specification output: `pin`, `fork`, a defined alternative, or `confirmation required`, plus the document or sample that supports that classification.
Step 3: Confirm pitch and contact geometry
Pitch is the center-to-center spacing between successive contact positions. In a regular lineup of equal-width modular devices, the busbar pitch often follows the device terminal spacing. Mixed widths, distributed-neutral arrangements, and auxiliaries can create a different pattern.
Record both the spacing and the contact geometry:
Center-to-center pitch
Pin width and contact length, or fork width, opening, and contact length
Contact thickness where controlled by the product drawing
Required insertion or engagement position
Vertical and horizontal offset from the device reference surface
Clearance from insulation, terminal shrouds, and adjacent components
KASEEY's published busbar range illustrates why these fields must be explicit. Selected S-series pin descriptions use 4 mm pin contacts, while selected G-series fork descriptions use 11 mm fork contacts. Published families also differ in contact length and finished length. These are model-family examples, not universal dimensions.
Do not use nominal device width as the only pitch evidence. Verify the terminal centers on the exact device drawing or an approved sample.
Specification output: a controlled interface line such as `pin contact; width __ mm; contact length _ mm; pitch __ mm`, with unknown values left for confirmation rather than guessed.
Step 4: Map poles, phase sequence, and neutral positions
Pole count describes how many conductive paths the busbar carries, but it does not fully describe their physical sequence. Build a contact-by-contact map across the complete lineup.
Common arrangements may include:
Single-phase repetition
Two- or three-phase repetition
Four-conductor L1-L2-L3-N patterns
1P+N device patterns
Distributed-neutral patterns
Mixed RCCB/MCB or RCBO arrangements
The Schneider Electric comb-busbar selection guide shows why the sequence must be explicit: its product-specific examples distinguish standard pole arrangements, distributed neutral, module counts, and layouts containing auxiliaries. Those examples apply to the named Schneider systems, but the selection principle is broader—map the actual device arrangement rather than inferring it from “3P” or “3P+N.”
Create a simple lineup table:
| Physical position | Device terminal | Required conductor | Busbar contact present? |
|---|---|---|---|
| 1 | Device A terminal 1 | L1 | Yes / no |
| 2 | Device A terminal 2 | L2 | Yes / no |
| 3 | Device A terminal 3 | L3 | Yes / no |
| 4 | Device A terminal 4 | N | Yes / no |
| … | Continue across the full lineup | Confirm sequence | Confirm alignment |
The completed table should reveal skipped positions, wider devices, neutral repetition, and interruptions before a physical sample is made.
Specification output: pole configuration plus the exact repeating or non-repeating sequence, supported by the circuit diagram and device lineup.
Step 5: Select cross-section and documented electrical ratings
Cross-section is an essential conductor parameter, but it is not a universal current-selection shortcut. Do not create a generic rule such as “X mm² always equals Y A” for every busbar.
Review the following together:
System voltage and frequency where relevant
Design current and protective-device arrangement
Incoming feed position and whether the busbar is fed from one end, the center, or another approved point
Product-specific current and voltage data
Conductor cross-section and construction
Connected device terminal data
Enclosure and installed conditions
Short-circuit or other performance data required by the project, where published and applicable
Destination-market and assembly requirements
KASEEY publishes cross-section and current-related data for named product families. Some descriptions label the value as a reference current. Keep that wording attached to the exact model and confirm project suitability from the product documentation and complete assembly conditions.
If the required electrical data is absent from the proposed product document, request it. Do not fill the gap by borrowing a rating from a busbar with a similar-looking conductor.
Specification output: required conductor cross-section plus the exact product-specific rating evidence and project conditions used for approval.
Step 6: Calculate tooth count, modules, and finished length
Determine how many contact positions are needed and how they align with device modules.
Count physical positions
Start from the device schedule, not the outgoing-circuit count. A multi-pole device occupies more positions than a 1P MCB, and an auxiliary can add width without requiring a main busbar contact.
For each position, mark:
Device width in modules or controlled millimetres
Whether an active busbar contact is required
Which phase or neutral reaches that contact
Any skipped or insulated position
Start and end clearances
Define length form
Decide whether the project needs:
A fixed-length closed busbar
A standard finished length
A longer busbar intended for an approved cutting process
A custom finished length
KASEEY's published range includes both compact closed products and longer finished busbar families. The existence of multiple length forms does not mean every product may be modified in the same way. Cutting method, end insulation, exposed conductor treatment, and dimensional tolerances must follow the exact product instructions or an approved supplier process.
Check enclosure fit
The finished busbar must fit the usable panel width while leaving the required space for end treatment, incoming connection, and adjacent components. Confirm that the first and last contacts align with the intended terminals after all device and auxiliary widths are included.
Specification output: exact active-contact count, physical-position map, and overall or finished length with defined end condition.
Step 7: Specify feed method, end treatment, and accessories
The conductive comb is only one part of the assembly. Define how power enters the busbar and how exposed or unused positions are controlled.
Depending on the selected system, the bill of materials may need:
Incoming connector or feed terminal
End caps
Protective covers
Tooth or contact covers for unused positions
Wiring bridges or related connection parts
Phase or circuit marking
Mounting or spacing accessories
Packaging that protects contact geometry during transport
Confirm whether the feed arrangement changes the documented electrical boundary. If the busbar has been shortened, specify the approved end treatment and inspection criteria.
KASEEY's modular-device busbar systems organize the discussion around the terminal, conductor definition, accessories, sample fit, and repeat supply rather than treating the bare busbar as an isolated item.
Specification output: a complete accessory list and a drawing showing the feed point, unused contacts, and both ends.
Step 8: Create the approval and repeat-order package
Before volume supply, convert the selected configuration into controlled evidence. A useful package includes:
Customer project or assembly reference
Full device schedule and circuit arrangement
Busbar model or controlled drawing revision
Material and cross-section
Pin or fork geometry
Pitch, poles, phase sequence, and contact count
Overall/finished length and end condition
Product-specific electrical data used for review
Accessories and incoming connection
Target market and required documents
Marking and packaging
Approved sample or first-article record
Repeat-order reference and revision-control method
If the protective-device platform, pitch, sequence, or geometry is nonstandard, route the project through a custom busbar and OEM review. Custom development should begin from an approved interface drawing or physical device sample, not an unsupported compatibility claim.
Hypothetical worked specification
The following example demonstrates the output format only. The blank values must be completed from the exact device and project documentation; it is not a product recommendation.
| Field | Hypothetical project entry |
|---|---|
| Device lineup | One 4P RCCB followed by nine 1P MCBs; exact manufacturer and models attached |
| Connection side | Bottom, subject to device documentation |
| Interface | Pin candidate; terminal drawing and sample review required |
| Contact geometry | Pin width ___ mm; pin length ___ mm; clamp position per attached drawing |
| Pitch | ___ mm center-to-center, verified across the complete lineup |
| Conductors | L1-L2-L3-N through the RCCB, followed by defined phase repetition across outgoing MCBs |
| Cross-section | ___ mm², selected against project current and product-specific data |
| Contact positions | Per attached position map; auxiliaries and skipped positions identified |
| Finished length | ___ mm including approved end condition |
| Feed and accessories | Incoming connector, end caps, unused-contact protection, marking |
| Target market | ___ |
| Quantity | Prototype ___; production ___ |
| Approval | Drawing review, physical sample fit, documentation review, signed reference |
The value of the example is the completeness of the fields. It deliberately does not insert a universal pitch, cross-section, or current value.
Final MCB busbar RFQ checklist
Send all applicable items in one technical package:
Device manufacturer and exact model references
Device types, poles, quantities, and left-to-right order
Auxiliaries, spacers, or mixed-width components
Connection side and approved busbar terminal
Terminal drawing, clear photographs, or physical sample
Pin, fork, or alternative interface
Contact width, length, and other controlled geometry
Pitch and position map
Pole count, phase sequence, and neutral pattern
System voltage, design current, feed arrangement, and required rating evidence
Conductor cross-section
Active contacts, modules, skipped positions, and finished length
Incoming connector, end caps, covers, and unused-contact treatment
Target market and document requirements
Quantity, marking, and packaging
Sample or first-article approval requirement
Controlled repeat-order reference
The selection is complete when the reference is repeatable
An MCB busbar is not fully selected when pin or fork, poles, and cross-section have been chosen. Selection is complete when the exact device lineup, interface, geometry, conductor sequence, ratings, length, accessories, and approval evidence point to one controlled reference.
To request a KASEEY review, submit the completed checklist through the contact page. Where fit cannot be confirmed from documentation, include a device sample or agree on a sample-approval stage before production ordering.
