Ground Bar Hole, Port, Lug, Terminal & Position Counts
Ground bars are frequently described by the number of holes, ports, lugs, terminals, or usable conductor positions they provide. A buyer may request a 12 hole ground bar, a six-port terminal bar, or a grounding busbar with ten connection points, but these descriptions do not always represent the same physical design.
One hole may be used for mounting rather than electrical connection. A single lug can also require two holes, while one large terminal may accept several conductors. For this reason, the required number of grounding connections should be confirmed together with hole diameter, thread, spacing, conductor size, lug type, and mounting method.
Carsai manufactures custom copper, tinned copper, aluminum, and brass ground bars with customer-defined hole and terminal layouts. We can supply the machined bar alone or assemble it with studs, terminal screws, compression lugs, insulators, brackets, covers, and mounting hardware.
For the complete product range, visit our ground bar and grounding busbar manufacturer page.
What Do Hole, Port, Lug, Terminal, and Position Mean?
These terms are related, but they should not automatically be treated as interchangeable.
Hole
A hole is a physical opening in the metal bar. It may be:
- A plain through-hole
- A tapped hole
- A countersunk hole
- A counterbored hole
- A mounting hole
- A terminal hole
- Part of a two-hole lug pattern
A ground bar described as having eight holes does not necessarily provide eight conductor connections if two of those holes are used for mounting.
Port
A port normally means a usable conductor connection. Depending on the product, one port may consist of a tapped hole, stud, mechanical lug, screw-clamp terminal, or two-hole compression-lug pattern.
Lug
A lug is a connector attached to the bar for terminating a cable. It can be installed at the factory or supplied loose with the grounding assembly.
Terminal
A terminal is a defined electrical connection point. One terminal may use one hole, two holes, a stud, or a separate mechanical connector.
Position
A position usually refers to one planned connection location. It is useful when the final hardware may vary but the buyer needs a specific number of usable conductor points.
The drawing should state both the total number of physical holes and the number of usable electrical connections.
Common Ground-Bar Connection Counts
The following descriptions are commonly used for custom grounding products:
| Connection count | Common product descriptions | Typical uses |
|---|---|---|
| 2 | ground bar 2 hole, 2 hole ground bar, 2 terminal ground bar | Small enclosures, one incoming and one outgoing connection |
| 3 | 3 hole ground bar, 3 lug ground bar, 3 terminal ground bar | Compact machinery, local grounding points |
| 4 | ground bar 4 hole, ground bar 4 port, 4 hole ground bar, 4 lug ground bar, 4 port ground bar | Junction boxes, small panels and equipment |
| 5 | 5 hole ground bar, 5 terminal ground bar, 5 port ground bar, 5 position ground bar, 5 lug ground bar | Compact control cabinets and local distribution |
| 6 | ground bar 6 hole, ground bar 6 port, 6 port ground bar, 6 hole ground bar, 6 lug ground bar, 6 position ground bar, 6 terminal ground bar | Electrical panels, DIN-rail assemblies and cabinets |
| 7 | 7 terminal ground bar, 7 hole ground bar, 7 port ground bar, 7 position ground bar, 7 position grounding bar | Equipment cabinets and custom multi-circuit assemblies |
| 8 | ground bar 8 hole, 8 port ground bar, 8 hole ground bar, 8 terminal ground bar, 8 position ground bar, 8 lug ground bar | Panels, telecom equipment and industrial enclosures |
| 9 | 9 hole ground bar, 9 terminal ground bar | Custom panels requiring an uneven terminal count |
| 10 | ground bar 10 hole, 10 hole ground bar, 10 terminal ground bar, 10 position grounding bar | Larger cabinets and distribution assemblies |
| 12 | ground bar 12 hole, ground bar 12 terminal, 12 hole ground bar, 12 port ground bar | Panelboards, telecom racks and industrial systems |
| 20 | 20 hole ground bar | Large cabinets, equipment lineups and room-level grounding |
These descriptions identify the intended capacity, but a production drawing is still required to define the actual layout.
Two-Hole Ground Bars
A ground bar 2 hole design is one of the simplest configurations. It may have one hole for an incoming grounding conductor and one for an outgoing conductor.
However, a 2 hole ground bar can also mean:
- Two electrical terminal holes plus separate mounting holes
- One two-hole compression-lug pattern
- Two tapped holes for small conductors
- Two studs installed on a copper bar
- One incoming lug and one enclosure-bonding connection
A 2 terminal ground bar should provide two usable electrical connection points, but it may contain more than two physical holes when mounting and support holes are included.
The RFQ should therefore identify which holes are terminals and which are used to mount the bar.
Three-Hole and Three-Lug Ground Bars
A 3 hole ground bar is suitable for a compact enclosure or equipment assembly with only a few grounding conductors.
A 3 lug ground bar normally means three cable lugs are attached to the bar. Each lug may use one or two mounting holes, so a three-lug bar could contain three, six, or more physical holes.
Similarly, a 3 terminal ground bar refers to three usable connection positions rather than a guaranteed three-hole layout.
Typical configurations include:
- One large incoming lug and two smaller outgoing terminals
- Three equal screw terminals
- Three studs with nuts and washers
- One two-hole lug plus one single-hole terminal
- Three cable-shield termination positions
Lug width and conductor bend radius should be considered even on a compact three-position bar.
Four- and Five-Position Ground Bars
Four- and five-position bars are widely used in junction boxes, small control panels, machine enclosures, generator controllers, solar equipment, and battery cabinets.
A ground bar 4 hole or 4 hole ground bar may contain four tapped conductor holes. A ground bar 4 port or 4 port ground bar should instead provide four usable conductor connections.
A 4 lug ground bar may require considerably more space because each lug has a body width, cable entry, fastener arrangement, and conductor bend radius.
Five-position products include:
- 5 hole ground bar
- 5 terminal ground bar
- 5 port ground bar
- 5 position ground bar
- 5 lug ground bar
For a five-position bar, one connection may be larger than the remaining four. This structure is common where one incoming grounding cable feeds several smaller equipment-grounding conductors.
Six- and Seven-Position Ground Bars
A six-position bar provides useful capacity without occupying the space required by a long distribution bus.
Common descriptions include ground bar 6 hole, 6 hole ground bar, ground bar 6 port, and 6 port ground bar.
The same general product may also be ordered as a:
- 6 lug ground bar
- 6 position ground bar
- 6 terminal ground bar
These versions may have different physical constructions. A six-lug assembly can be much larger than a six-hole screw-terminal bar because compression lugs need more spacing.
Seven-position designs are useful when a project has a specific number of circuits and does not need a standard even-numbered layout. The terms 7 terminal ground bar, 7 hole ground bar, 7 port ground bar, and 7 position ground bar should be clarified in the drawing.
A 7 position grounding bar should normally provide seven usable connection locations, even if additional mounting or support holes are present.
Eight-Hole Grounding Busbars
Eight-position bars are common in electrical panels, telecom enclosures, industrial equipment, and control cabinets.
An 8 hole ground bar may use one row of eight holes or two rows of four. Other configurations include:
- ground bar 8 hole
- 8 port ground bar
- 8 terminal ground bar
- 8 position ground bar
- 8 lug ground bar
Some project specifications use the descriptions grounding bus bar 8 holes or grounding busbar 8 holes. Both usually describe a grounding busbar containing eight terminal holes, but the specification should still confirm whether mounting holes are included in that number.
For larger lugs, a two-row design can provide more space than eight closely spaced holes in one line. However, cable routing and tool access must be checked before finalizing the pattern.
Six-, Eight-, and Ten-Hole Grounding Busbars
Grounding-busbar terminology is commonly used for bars serving several circuits or equipment sections.
Typical product searches include:
- grounding busbar 6 holes
- grounding busbar 8 holes
- grounding busbar 10 holes
These phrases are useful for identifying the approximate number of connections, but they do not specify:
- Hole diameter
- Tapped or through-hole construction
- Thread standard
- Bar thickness
- Hole spacing
- Conductor range
- Mounting method
- Material or plating
- Whether all holes are electrically usable
For example, a ten-hole grounding busbar may contain eight conductor terminals and two support holes. If ten electrical connections are required, the drawing should state “10 usable grounding terminals plus mounting holes.”
Ten- and Twelve-Position Ground Bars
A ground bar 10 hole or 10 hole ground bar is suitable for medium-sized electrical and industrial assemblies. A 10 terminal ground bar should provide ten usable terminal positions, while a 10 position grounding bar may use holes, studs, or lugs depending on the design.
A 12 hole ground bar provides additional capacity and is commonly used in:
- Electrical panels
- Panelboards
- Control cabinets
- Telecom racks
- Server cabinets
- Battery systems
- Industrial equipment
- Building grounding systems
Equivalent descriptions include ground bar 12 hole, ground bar 12 terminal, and 12 port ground bar.
A 12-position design may use:
- Twelve equal tapped holes
- Ten small terminals plus two large lugs
- Two rows of six holes
- Four two-hole lug patterns plus four single-hole terminals
- Twelve studs
- One main incoming connection and eleven branch terminals
The best layout depends on the conductor and lug sizes rather than the count alone.
Twenty-Hole Ground Bars
A 20 hole ground bar is generally intended for a large cabinet, equipment lineup, electrical room, telecom facility, or industrial grounding system.
A long twenty-hole bar requires careful planning of:
- Bar length and thickness
- Hole spacing
- Support quantity
- Support locations
- Lug orientation
- Conductor routing
- Spare terminal positions
- Mechanical deflection
- Installation access
- Packaging and transportation
If every connection uses a large compression lug, twenty positions may require a significantly longer bar than twenty small tapped terminals.
Long bars may also require an additional center support to prevent bending during installation.
Ground Bars for 2/0 and 4/0 Lugs
Large grounding conductors are often identified by American wire sizes such as 2/0 and 4/0 AWG.
A ground bar with 2 0 lug should include a lug rated for the specified 2/0 conductor and compatible with the conductor material. A ground bar with 4 0 lug requires a larger lug and usually more installation space.
The drawing should define:
- Conductor size and material
- Mechanical or compression lug
- One-hole or two-hole mounting
- Lug manufacturer or dimensional standard
- Mounting-hole diameter
- Center-to-center spacing
- Required fasteners
- Lug orientation
- Installation torque
- Whether the lug is installed or supplied loose
The text “2 0” or “4 0” alone does not define the mounting-hole pattern. Different lug designs for the same conductor size can use different hole diameters and spacing.
Hole Diameter and Thread Selection
Ground-bar terminal holes may be plain, tapped, countersunk, counterbored, or fitted with studs.
Plain through-holes
These are commonly used with compression lugs, bolts, washers, and nuts. The hole must suit the fastener while maintaining enough material around the edge.
Tapped holes
Tapped holes allow screws or studs to be installed directly into the bar. The bar must be thick enough to provide adequate thread engagement.
Common thread systems include:
- Metric threads such as M4, M5, M6, M8, M10, and M12
- Imperial machine-screw threads
- UNC or UNF threads
- Customer-specified stud threads
Two-hole lug patterns
Two-hole lugs reduce rotation and are common for larger conductors. The drawing must define both hole diameter and center-to-center spacing.
Do not identify a two-hole lug pattern only by conductor size because lug dimensions can vary between suppliers.
Hole Spacing and Edge Distance
Hole spacing affects conductor access, mechanical strength, and manufacturability.
Insufficient spacing can cause:
- Lug bodies to overlap
- Washers to interfere
- Limited tool access
- Conductors to bend too sharply
- Reduced copper between holes
- Difficulty adding or removing terminals
- Increased risk of installation errors
The drawing should show center-to-center dimensions rather than relying on visual proportions.
Edge distance should also be sufficient to avoid weakening the bar around terminal and mounting holes.
Terminal Count vs. Current Capacity
A greater number of terminals does not automatically mean a higher electrical capacity.
Ground-bar performance depends on:
- Material
- Width and thickness
- Connection resistance
- Lug contact area
- Fastener torque
- Conductor size
- Temperature rise
- Fault-current requirements
- Installation environment
A twelve-hole bar can have a smaller conductive cross-section than a six-hole heavy-duty bar. The terminal count and electrical rating should therefore be evaluated separately.
Material and Finish Options
Custom multi-position ground bars can be made from:
Bare copper: commonly selected for indoor panels and controlled industrial environments.
Tinned copper: used where improved surface protection is required, including telecom, outdoor, marine, and humid applications.
Aluminum: offers lower weight but requires compatible lugs, suitable surface preparation, and an appropriate cross-section.
Brass: suitable for some compact terminal bars requiring many tapped holes and good machinability.
Material selection can also affect the recommended hole size, thread depth, plating process, and lug compatibility.
Direct and Insulated Mounting
Mounting holes should not be counted as conductor positions unless they intentionally form part of the electrical connection.
A bar can be:
- Directly mounted to an enclosure
- Installed on insulating standoffs
- Attached to a mounting plate
- Fixed to a wall bracket
- Mounted vertically in a rack
- Installed inside a protective box
- Supplied with a removable cover
When insulators are used, the support-hole pattern must be separated from the terminal layout. The complete fastener arrangement should prevent unintended contact where electrical isolation is required.
Custom Manufacturing and Inspection
Carsai can manufacture ground bars with custom terminal counts through:
- Material cutting
- CNC drilling or punching
- Tapping
- Countersinking or counterboring
- Milling
- Deburring
- Bending where required
- Tin or nickel plating
- Stud, lug, and hardware assembly
- Insulator and bracket installation
- Dimensional inspection
- Labeling and packaging
Inspection can cover:
- Total hole quantity
- Terminal quantity
- Hole diameter
- Thread size
- Center-to-center spacing
- Edge distance
- Lug pattern
- Stud height
- Bar dimensions
- Plating appearance
- Insulator position
- Hardware completeness
A hole-location table can be used for complex designs to prevent ambiguity and simplify inspection.
Information Required for Quotation
To quote a custom multi-position ground bar, provide:
- Drawing or dimensioned sketch
- Material and finish
- Bar length, width, and thickness
- Number of usable conductor positions
- Total physical hole quantity
- Mounting-hole locations
- Hole diameter
- Thread size and depth
- Lug or terminal type
- Conductor sizes
- Hole spacing and edge distance
- Stud and fastener requirements
- Direct or insulated mounting
- Quantity
- Delivery destination
A request stating only “12-hole ground bar” is not enough for accurate manufacturing because the hole type, dimensions, spacing, and mounting arrangement remain unknown.
Frequently Asked Questions
Does a 12-hole ground bar always provide twelve terminals?
Not necessarily. Some holes may be used for mounting or may form pairs for two-hole lugs. Specify the number of usable electrical connections separately.
What is the difference between a port and a hole?
A hole is a physical feature in the bar. A port normally means one usable conductor connection, which may contain one hole, two holes, a stud, or a mechanical lug.
Can one bar contain different terminal sizes?
Yes. One bar can combine small tapped holes, larger studs, one-hole lugs, two-hole lugs, and dedicated mounting holes.
Can you supply the lugs and terminal hardware?
Yes. Lugs, studs, screws, washers, nuts, insulators, brackets, and covers can be installed or supplied loose according to the drawing.
Can you manufacture nonstandard terminal counts?
Yes. We can produce ground bars with the exact number of holes, ports, lugs, terminals, or positions required by the project.
Can the holes be arranged in two rows?
Yes. Two-row layouts are useful for wider bars, higher terminal counts, and applications requiring more space between large lugs.
Request a Quote
Carsai manufactures custom ground bars with 2 to 20 or more holes, ports, lugs, terminals, and conductor positions for electrical panels, telecom racks, control cabinets, equipment enclosures, and industrial grounding systems.
Send us your drawing, material, bar dimensions, hole count, terminal count, hole diameter, thread sizes, spacing, conductor sizes, mounting arrangement, accessories, and quantity for quotation.
