Buying cables is hard. Especially when you see numbers like 12/20kV. It sounds technical. But it is actually simple. This guide helps you understand everything about 12/20kV medium voltage power cables. We are a cable factory. We make these cables every day. We will explain it in easy words. You will learn what it is. You will learn the specs. And you will learn how to buy the right one.
What is 12/20kV Medium Voltage Cable?
Let’s start with the basics. This cable carries electricity. It is for medium voltage (MV) use. The “12/20kV” part tells us the voltage level.
Here is what the numbers mean:
- Uo: This is 12 kV. It is the voltage from the core to the ground.
- U: This is 20 kV. It is the voltage between the cores (phases).
- Um: This is the highest voltage the system can handle. It is usually 24 kV.
We use this cable in cities and factories. It connects power stations to buildings. It also connects big machines. It is not for your house. House wiring is low voltage. This is for big power. It is strong. It is safe. And it lasts a long time.
Why Use 12/20kV Cables?
Why do people choose this specific cable? There are many reasons. First, it is standard. Almost every country uses it. Second, it is efficient. It moves a lot of power without losing much energy. Third, it is safe. It has thick insulation. This stops electricity from leaking.
You see these cables underground. You also see them in cables tunnels. They power big pumps. They power conveyor belts in mines. They power airports and hospitals. If a place needs a lot of steady power, they use 12/20kV cables. It is the workhorse of the power industry.
How is the Cable Built?
A cable is not just one piece of wire. It has layers. Each layer has a job. Let’s look at the inside. We use a standard called IEC 60502-2. Most factories follow this.
The Conductor (The Core)
This is the metal part. It carries the current. It is usually copper or aluminum. Copper is better for conductivity. Aluminum is lighter and cheaper. The conductor can be solid or stranded. Stranded means many small wires twisted together. This makes the cable flexible.
The Insulation (The Shield)
This is the most important part. It stops the electricity from escaping. For 12/20kV, we use XLPE. This stands for Cross-Linked Polyethylene. It is a special plastic. It handles heat very well. It is much better than old PVC or oil paper. XLPE is strong. It does not melt easily.
The Screen (The Shield)
We put a screen over the insulation. It is usually copper wire or tape. It creates a ground path. If the insulation breaks, the screen catches the current. This protects people and machines.
The Armor (The Protection)
This is the hard outside layer. It protects the cable from physical damage. We use steel wire or steel tape. If you bury the cable underground, rocks might hit it. The armor stops the rocks from breaking the core. It also stops rats from biting the cable!
The Outer Sheath (The Jacket)
This is the final skin. It is usually black polyethylene (PE). It stops water and UV light. It also protects against chemicals in the soil. We can make it fire-resistant if you need that.
Technical Specifications You Need to Know
When you ask for a quote, you need to give specs. Here is a simple table. It shows common specs for 12/20kV cables.
| Item | Specification | Details |
|---|---|---|
| Standard | IEC 60502-2 / BS 5467 | International quality standard |
| Voltage | 12/20 (24) kV | Rated voltage Uo/U (Um) |
| Conductor | Copper / Aluminum | Class 1 or Class 2 stranded |
| Insulation | XLPE | Cross-linked polyethylene |
| Screen | Copper Tape/Wire | 100% coverage |
| Armor | SWA / STA | Steel Wire or Steel Tape |
| Sheath | Black PE | UV and water resistant |
| Cores | 1C, 3C | Single core or Three core |
| Size (mm2) | 25mm2 – 630mm2 | Cross-sectional area |
A Note on Current Rating (Ampacity)
How much current can it carry? It depends on the size. It also depends on the ground temperature.
- A 95mm2 cable carries about 250 Amps in air.
- A 300mm2 cable carries about 500 Amps in air.
- A 500mm2 cable carries about 650 Amps in air.
- Note: If you bury it, the numbers go down because soil is hotter.
Always ask the engineer for the exact ampacity. Do not guess. Safety comes first.
Single Core vs. Three Core Cables
You have two main choices. You can buy Single Core (1C) or Three Core (3C).
Single Core Cables
This cable has one big conductor. You need three cables for a 3-phase system. You put them side by side.
- Pros: Easy to install. Good for long distances.
- Cons: You need more space. You need special clamps to hold them.
- Warning: Do not use magnetic clamps on single cores. It causes heat. Use non-magnetic materials.
Three Core Cables
This cable has three conductors inside one jacket.
- Pros: Saves space. Easier to handle. Cheaper to install.
- Cons: Heavier. Harder to pull around corners.
- Use case: Best for short distances inside buildings or panels.
Common Tests for Quality Control
How do you know the cable is good? We do tests. You should ask for the test report.
Routine Tests (Do this for every meter)
- Voltage Test: We put high voltage on the conductor for 5 minutes. It should not break down.
- Resistance Test: We check the conductor resistance. It must be low.
- Partial Discharge (PD) Test: We check for tiny sparks inside the insulation. Good cables have zero sparks.
Type Tests (Do this once a year)
- Heating Cycle Test: We heat the cable. Then we cool it. We do this many times. The insulation should not crack.
- Impulse Test: We hit it with a high voltage spike. It simulates lightning.
Ask your supplier for these reports. If they cannot provide them, do not buy.
Where is This Cable Used?
This cable is everywhere in heavy industry. Here are the top 5 places:
- Power Grids: Connecting substations to distribution points.
- Industrial Plants: Steel mills, cement factories, and chemical plants.
- Infrastructure: Airports, subways, and tunnels.
- Renewable Energy: Connecting wind turbines and solar farms to the grid.
- Offshore: Oil rigs and underwater connections (with special armor).
How to Choose the Right Supplier
You are looking for a factory. You want a good price. But you also want quality. Here is a checklist:
- Experience: Do they make MV cables? LV (Low Voltage) is different.
- Certificates: Do they have ISO 9001? Do they have CE, UL, or IECEx?
- Material: Do they use 100% virgin XLPE? Or recycled material? (Always ask for virgin).
- Testing: Do they have a high-voltage lab in the factory?
- Packing: Can they pack on steel drums? Can they put cable on pallets?
- Delivery: Can they ship on time?
Don’t just pick the cheapest one. A bad cable can cause a fire. It can cost millions in downtime. Spend a little more for safety.
Frequently Asked Questions
Can I use 12/20kV cable for 11kV systems?
Yes. 12/20kV is the standard for 11kV networks. The “12kV” rating is higher than 11kV. It is safe to use.
What is the difference between XLPE and PVC?
XLPE is for medium voltage. PVC is for low voltage (up to 1kV). XLPE handles more heat. XLPE is stronger. Never use PVC for 12/20kV.
How deep should I bury this cable?
Usually, you bury it 700mm to 1000mm deep. If you put it under a road, go deeper (1000mm). Use warning tape above the cable.
Can I pull this cable in winter?
Be careful. XLPE gets stiff in the cold. If you pull too hard, the insulation might crack. Try to install it when it is warmer than 0 degrees Celsius.
Conclusion
The 12/20kV medium voltage power cable is a key product. It moves big power safely. It uses XLPE insulation. It has steel armor for protection. You can choose copper or aluminum. You can choose single core or three core.
When you buy, check the specs. Ask for the test report. Look at the factory. Good quality saves money in the long run.
We hope this guide helped you. If you need a quote for 12/20kV cable, contact us. We make high-quality cables at fair prices. We ship to the USA, UK, Australia, and Africa. Let’s build your next project together.