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In a low-voltage switchboard, cabinet space is rarely consumed by the fuse switch alone.
The actual space requirement also includes mounting structures, busbar connections, cable routing, terminals, bending space, and the clearance needed to install and maintain each component.
This is why replacing a traditionally fixed fuse switch with a busbar-mounted fuse switch can change more than the mounting method. It can change how the entire distribution section is arranged.
But how much space can actually be saved?
There is no single percentage that applies to every switchboard. The result depends on the number of devices, busbar arrangement, cable routing, cabinet dimensions, and the original mounting method. GRL states that its Busbar System can reduce installation time and cabinet space usage by up to 60% in applicable configurations.
The more useful question for a switchboard designer is therefore: where does the space saving come from, and how should it be estimated?
A fixed-mounted fuse switch is normally attached to a mounting plate or other fixed structure. Depending on the switchboard design, the installation may require mounting holes, bolts, support structures, and additional space for incoming and outgoing connections.
For a single device, the difference may appear relatively small. The effect becomes more noticeable when several fuse switches are installed in the same cabinet.
| Space Requirement | Fixed-Mounted Installation | Busbar-Mounted Installation |
|---|---|---|
| Device body | Required | Required |
| Mounting structure | Usually required | Integrated with busbar mounting arrangement |
| Mounting holes | May be required | Not required in the same way for busbar mounting |
| Connection to busbar | Separate connection arrangement may be required | Direct busbar mounting interface |
| Cable routing | Can require additional routing space | Can be simplified depending on the system configuration |
| Future repositioning | May require mechanical modification | Components can be repositioned on the busbar system |
The important point is that a busbar-mounted design does not make the fuse switch itself physically smaller. Instead, it can reduce the additional installation space around the device.
The main difference is how the fuse switch is connected to the distribution system.
With a conventional fixed installation, the switch is mounted to a support structure and then connected to the electrical distribution path. This can require additional mechanical and electrical connection work.
With a busbar-mounted fuse switch, the device is designed to attach directly to the busbar system. GRL’s DNH1 series, for example, is available in both fixed and busbar-mounted versions.
Busbar Mounted Fuse Switch
Busbar mounting: Busbar → Mounting interface → Fuse switch disconnector → Outgoing circuit
This changes the physical architecture of the switchboard.
Instead of treating every fuse switch as an independently mounted component, the busbar becomes both the electrical distribution path and the mounting infrastructure.
No.
This is an important distinction when evaluating busbar systems.
GRL’s published figure of up to 60% reduction in cabinet space usage refers to the overall installation approach, not a claim that the physical dimensions of every individual fuse switch are reduced by 60%.
The actual space saving can come from several areas:
Therefore, a realistic space calculation should compare the complete installation footprint, rather than comparing the dimensions of two switch bodies.
A simple way to evaluate a project is to divide the cabinet requirement into three areas:
| Area | What to Measure | Why It Matters |
|---|---|---|
| Component footprint | Width × height × depth of installed devices | Shows the physical space occupied by the equipment |
| Connection space | Busbar, terminals, cables, lugs and connection clearance | Often adds significant space beyond the device body |
| Installation space | Mounting plates, brackets, holes and service clearance | Determines how efficiently devices can be arranged |
The comparison can then be expressed as:
Space saving (%) = (Traditional installation space − Busbar installation space) ÷ Traditional installation space × 100%
For example, suppose a distribution section requires 1000 units of usable cabinet space with a conventional installation arrangement. If the equivalent busbar-mounted arrangement requires 700 units, the calculated space reduction would be:
(1000 − 700) ÷ 1000 × 100% = 30%
This example is only an illustration. It should not be interpreted as a guaranteed saving for a specific GRL product or switchboard.
The space advantage can become more noticeable when several outgoing circuits are installed in the same distribution section.
Imagine a cabinet containing six outgoing circuits. If every fuse switch requires an independent mounting position and connection arrangement, the designer must repeatedly allocate space for mounting, wiring, terminals, and access.
A busbar-mounted architecture creates a common installation structure-Multiple Fuse Switches on One Busbar
This makes the cabinet layout more modular. GRL also describes its Busbar System as allowing components to be repositioned or swapped on the busbar, which can be useful when a switchboard requires modification or expansion.
In other words, the benefit is not simply “less space per switch.” It is also “less duplicated installation infrastructure between switches.”
Cabinet space is only one part of the comparison.
The installation method can also affect engineering and assembly time.
For example, GRL describes its busbar-mounted DNH1 design as using a dedicated installation structure that can be mounted onto the busbar without the same drilling process required for fixed installation. The company’s product information specifically compares the DNH1 busbar-mounted version with its fixed-mounted version.
| Installation Step | Traditional Fixed Mounting | Busbar-Mounted Design |
|---|---|---|
| Prepare mounting position | Required | Defined by busbar arrangement |
| Drilling / mounting holes | May be required | Can be avoided in the busbar mounting process |
| Mechanical fastening | Separate mounting operation | Mount directly to busbar interface |
| Electrical connection | Separate connection arrangement | Integrated with busbar mounting system |
| Repositioning | May require new mounting work | Can be repositioned along the system depending on configuration |
This can be particularly useful for distribution cabinets that need frequent modification, expansion, or different outgoing circuit arrangements.
A busbar-mounted fuse switch is particularly relevant when cabinet space and distribution layout are important design constraints.
GRL’s DNH1G series is available in 160A, 250A, 400A, 630A and 800A versions, with both fixed and busbar installation options, depending on the model.
Space saving should not be the only selection criterion.
Before choosing a busbar-mounted fuse switch, check the complete interface between the switch, busbar and cabinet.
| Check | Question to Ask |
|---|---|
| Rated current | Does the switch match the required continuous current? |
| Rated voltage | Is the switch suitable for the system voltage? |
| Fuse size | Does the switch accept the required NH fuse size? |
| Busbar system | Does the mounting interface match the selected busbar? |
| Cabinet dimensions | Does the complete assembly fit the available space? |
| Connection direction | Are incoming and outgoing connections compatible with the cabinet layout? |
| Maintenance access | Can the fuse and switch be operated and maintained safely? |
| Additional functions | Are auxiliary contacts, microswitches or fuse monitoring required? |
For example, GRL’s DNH1 busbar-mounted products are available with optional fuse links, microswitches and fuse monitoring depending on the configuration.
A busbar-mounted fuse switch should not be evaluated simply by asking how many millimeters smaller the switch is.
The more useful comparison is between two complete cabinet architectures.
A conventional fixed installation may require separate mounting structures, connection arrangements and additional wiring space for each device. A busbar-mounted system uses the busbar as a common electrical and mechanical infrastructure, allowing multiple devices to be arranged around the same distribution structure.
GRL states that its Busbar System can reduce cabinet space usage by up to 60% in applicable configurations, while also reducing installation work and allowing components to be repositioned or swapped.
However, the actual saving for a particular project should always be calculated from the complete cabinet layout, including device dimensions, busbar arrangement, connection space, cable routing, and maintenance requirements.
Key takeaway: The main advantage of a busbar-mounted fuse switch is not that the switch itself becomes smaller. It is that the electrical connection, mechanical mounting, and component arrangement can be integrated into one distribution architecture, allowing the available cabinet space to be used more efficiently.
If you are designing a low-voltage switchboard and need to reduce cabinet space, simplify installation, or arrange multiple outgoing protection devices on a common busbar, GRL can provide busbar-mounted fuse switch configurations for different current ratings and applications.
The DNH1 series includes fixed and busbar-mounted versions, with options such as fuse links, microswitches and fuse monitoring depending on the model.
with your busbar size, rated current, fuse size, cabinet layout, and number of outgoing circuits to discuss a suitable configuration.
Request a Busbar Fuse Switch Solution | Explore DNH1G Fuse Switch Disconnectors | Learn About the GRL Busbar System
Recommended internal links: Busbar System, DNH1G Fuse Switch Disconnector, Fuse Switch Disconnector, LV Switchboard Protection, Busbar-Mounted Fuse Switch.
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