Copper Busbar | Copper Busbar Size and Current Rating | Copper Busbar Ampacity Chart | Choosing the Right Copper Busbar: Key Factors to Consider

Copper busbars are an essential component in electrical power distribution systems and are used to conduct electrical current between various components such as transformers, circuit breakers, and distribution panels. The specification of copper busbars depends on several factors such as maximum current, voltage drop, ambient temperature, and available space.

General Specifications for Copper Busbars:

1. Material: Copper busbars are typically made of high-conductivity copper with a minimum purity of 99.9%.

2. Cross-sectional area: The cross-sectional area of the busbar is determined by the maximum current that the busbar will carry. The current rating of the busbar is proportional to the cross-sectional area of the conductor.

3. Thickness: The thickness of the busbar is determined by the mechanical strength required to support the weight of the busbar and to withstand the electromagnetic forces that arise from high currents.

4. Shape: Copper busbars come in a variety of shapes including rectangular, square, round, and custom shapes. The shape of the busbar can affect its current-carrying capacity and voltage drop.

5. Surface finish: The surface finish of the busbar can impact its electrical conductivity and resistance to corrosion. Common surface finishes include bare copper, tin-plated copper, and nickel-plated copper.

6. Insulation: In some applications, copper busbars may need to be insulated to prevent electrical arcing and to protect personnel from electrical shock. Insulation can be achieved using a variety of materials such as PVC, epoxy, or silicone.

7. Mounting method: The mounting method for copper busbars can vary depending on the specific application. Common mounting methods include bolt-on and clamp-on.

Copper busbars are commonly used in electrical power distribution systems to conduct electrical current between various components such as transformers, circuit breakers, and distribution panels. The specification and selection of copper busbars depend on several factors such as the maximum current, voltage drop, ambient temperature, and available space.

General guidelines for selecting copper busbars:

1. Determine the maximum current: The maximum current that the busbar will need to carry is the primary factor in determining the size and thickness of the copper busbar. The current rating of the busbar is dependent on the cross-sectional area of the conductor.

2. Determine the voltage drop: The voltage drop across the busbar should be kept within acceptable limits. The voltage drop is dependent on the current, the length of the busbar, and the resistance of the copper.

3. Determine the ambient temperature: The ambient temperature affects the conductivity of copper. The maximum operating temperature of the copper busbar should be considered when selecting the thickness and size of the busbar.

4. Select the type of copper busbar: There are several types of copper busbars, including solid bars, laminated bars, and plated bars. The type of busbar selected will depend on the specific application and operating conditions.

5. Select the busbar shape: The shape of the busbar can impact the current-carrying capacity and voltage drop. The most common shapes are rectangular, round, and square.

6. Determine the mounting method: The mounting method will affect the size and shape of the busbar. The most common mounting methods are bolt-on and clamp-on.

Based on the above factors, a copper busbar selection chart can be created that lists the recommended size, thickness, shape, and current rating for various applications. However, it is important to note that the selection of a copper busbar should be done by a qualified electrical engineer or designer who has expertise in the specific application and operating conditions.

Copper busbars are available in a range of sizes and configurations to accommodate different electrical power distribution systems. The selection of a copper busbar depends on several factors such as the maximum current, voltage drop, ambient temperature, and available space. Here is a general copper busbar selection chart that can be used as a reference:

Copper Busbar Ampacity Chart

Busbar Size (mm)	Current Rating (A)	Voltage Drop (mV/A/m)
12 x 3	40	14.5
12 x 6	80	7.2
12 x 10	120	4.3
20 x 3	65	8.7
20 x 6	130	4.3
20 x 10	210	2.6
30 x 3	100	5.8
30 x 6	200	2.9
30 x 10	320	1.8
40 x 3	135	4.3
40 x 6	270	2.2
40 x 10	425	1.4
50 x 6	320	1.8
50 x 10	500	1.1
50 x 20	900	0.6
60 x 10	600	0.9
60 x 20	1050	0.5
80 x 10	850	0.7
80 x 20	1600	0.4
100 x 10	1050	0.5
100 x 20	1900	0.3

Frequently Asked Questions (FAQ) on Copper Busbar

1. What is a Copper Busbar?

A copper busbar is a solid strip or bar of copper that is used to conduct electricity within electrical installations. Copper is often used because of its excellent electrical conductivity, mechanical strength, and corrosion resistance.

2. Why is Copper Preferred for Busbars?

Copper is widely preferred for busbars due to its:

• High conductivity: Copper has a higher current-carrying capacity than aluminum.
• Durability: Copper is strong and has a long lifespan with resistance to oxidation and corrosion.
• Ductility: It can be easily fabricated into different shapes and sizes.

3. What Are the Common Applications of Copper Busbars?

Copper busbars are used in various applications, such as:

• Electrical panels and switchboards.
• Transformers.
• Power distribution in industrial plants.
• Electrical substations.
• Battery banks.

4. How Do I Choose the Right Size of a Copper Busbar?

The size of the copper busbar depends on the current load it needs to carry and the temperature rise allowed in the system. The busbar's cross-sectional area determines the current-carrying capacity (ampacity). You'll also consider factors like:

• Ambient temperature.
• Installation environment.
• Required voltage drop.

5. What is the Current Carrying Capacity of Copper Busbars?

The current carrying capacity of a copper busbar depends on its cross-sectional area, installation method, and ambient conditions. Below is a general guideline, although actual capacity can vary depending on specific conditions.

Copper Busbar Size and Current Rating

Copper busbars are typically available in various standard sizes (measured in mm for width and thickness). The current rating (ampacity) is based on the cross-sectional area and varies depending on the installation.

Busbar Size (Width x Thickness mm)	Cross-Sectional Area (mm²)	Approx. Current Capacity (A)
20 x 3	60	150
25 x 3	75	180
25 x 6	150	320
40 x 3	120	250
50 x 6	300	500
63 x 6	378	600
80 x 10	800	950
100 x 10	1000	1100
125 x 10	1250	1300

6. How is the Current Rating of Copper Busbars Calculated?

The ampacity of copper busbars is generally calculated based on:

• Cross-sectional area (width x thickness).
• Ambient temperature.
• Insulation type and installation method (enclosed or exposed).
• Maximum allowable temperature rise (often 30°C over ambient temperature).

7. What is a Copper Busbar Ampacity Chart?

A copper busbar ampacity chart provides the current-carrying capacity of different sizes of busbars based on their width, thickness, and cross-sectional area. This chart helps in selecting the appropriate busbar size for your specific application.

Here’s a simplified Copper Busbar Ampacity Chart for quick reference:

Busbar Size (Width x Thickness mm)	Current Capacity (A) at 30°C rise	Current Capacity (A) at 50°C rise
20 x 5	210	240
50 x 6	570	640
100 x 10	1100	1200
150 x 10	1500	1600
200 x 12	2100	2300

8. Can Copper Busbars be Used for Grounding?

Yes, copper busbars are commonly used for grounding purposes in electrical systems due to their excellent conductivity, which helps maintain low resistance for grounding circuits.

9. How Do You Joint Copper Busbars?

Copper busbars are usually joined using bolted joints or welded connections. Bolted joints are most common as they allow for easy disassembly and maintenance, while welding provides a more permanent connection.

10. What are the Standard Sizes for Copper Busbars?

Copper busbars come in a variety of standard sizes (width x thickness) based on the application. Common sizes include:

• Width: 20 mm, 25 mm, 50 mm, 100 mm, 150 mm, etc.
• Thickness: 3 mm, 5 mm, 6 mm, 10 mm, etc.

11. How Do Ambient Temperature and Installation Affect Busbar Ampacity?

Ambient temperature and installation type significantly affect the ampacity of a copper busbar. Higher ambient temperatures or enclosed installations can reduce the busbar's current-carrying capacity, so derating factors must be applied in such cases.