What Size of Armoured Cable for an EV Charger?

Many EV owners opt to install a dedicated EV charger at their homes for convenience and faster charging. However, to ensure a safe and effective charging solution, selecting the right size of armoured cable is crucial.

In this article, we will discuss the factors to consider when determining the appropriate size of armoured cable for your EV charger installation.

What’s the Importance of Armoured Cables?

Armoured cables are electrical cables designed for protection in challenging environments. They consist of a conductive core (wires) insulated with a non-conductive material, surrounded by a metallic layer for mechanical and environmental protection.

This metallic layer, often made of steel or aluminum, gives the cable its “armour.” Armoured cables are commonly used in situations where cables are exposed to physical damage, moisture, or other adverse conditions.

Why is Proper Sizing of Armoured Cables Important?

Selecting the correct size of armoured cable for your EV charger is vital for several reasons:

Safety Assurance: An undersized cable can lead to overheating due to the increased current passing through it. This can not only damage the cable but also pose a significant fire hazard. Proper sizing ensures that the cable can safely carry the load without risking electrical fires or accidents.

Efficiency: Properly sized cables are essential for maintaining high efficiency in electrical systems. Undersized cables can lead to voltage drops, where the voltage decreases as it travels along the cable. Voltage drops can cause inefficiency in the charging process, leading to longer charging times and decreased performance. When charging an EV, efficiency is vital to ensure you’re getting the maximum charging speed.

Preventing Overheating: Inadequate cable sizing can result in cables overheating, which not only jeopardizes safety but can also damage the insulation and conductors, leading to expensive repairs or replacements. A properly sized cable will operate within safe temperature limits, ensuring the longevity of the cable and reducing maintenance costs.

Future-Proofing: Properly sizing armoured cables also involves considering future needs. If you’re planning to upgrade your EV charger to a higher-capacity unit or add more charging points, having a cable with some extra capacity can save you from the need to rewire your installation later on. This future-proofing can save both time and money in the long run.

Reliability: A properly sized cable ensures that your EV charger functions reliably. You won’t have to worry about intermittent issues or unexpected interruptions in your charging sessions, providing peace of mind for EV owners.

Cost Savings: While it might seem tempting to cut costs by using smaller cables, the long-term cost implications can be significant. Using an appropriately sized cable from the outset can help you avoid the expense of repairs, replacements, or system upgrades that might be necessary if the cable is too small.

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What Factors to Consider When Choosing the Size of Armoured Cable?

Charger Capacity: The first step is to identify the charger’s capacity. EV chargers come in various sizes, typically measured in kilowatts (kW). For example, a Level 1 charger is typically around 2 kW, while a Level 2 charger can range from 3.5 kW to 22 kW. Knowing your charger’s capacity is essential for cable sizing.

Distance: The length of the cable run from the electrical panel to the EV charger location is crucial. Longer cable runs result in higher voltage drop, which can affect charging efficiency. Measure the distance accurately to calculate voltage drop.

Voltage: In North America, residential electrical systems usually operate at 120/240 volts, while some countries have different standards. Ensure your cable is rated for the appropriate voltage.

Load: Consider other electrical loads on the same circuit. If the circuit powers other appliances or outlets, factor in their power requirements when sizing the cable.

Voltage Drop: Voltage drop is the reduction in voltage along the cable’s length due to resistance. To maintain efficient charging, aim for a voltage drop of 3% or less. You can calculate voltage drop using online calculators or electrical engineering resources.

Also read: EV Battery in Hot Temperature: 5 Things to Know

What Size of Armoured Cable Do You Need?

Each case in different, but let’s assume the most popular case, that these are your specifications:

EV Charger:

  • Operating Voltage: 240 volts
  • Amperage: 32 amperes
  • Charging Capacity (Power): 7 kW
  • Charger Type: Level 2 (most typical for home charging)

EV:

  • Charging Capacity: 7 kW

Cable Size:

  • Cable Type: Copper is recommended for optimal conductivity and safety.
  • Voltage Drop: Aim for a voltage drop of 3% or less for efficient charging.
  • Typical Cable Length: For a typical home charging setup with a cable length of 25-50 feet (7.6-15.2 meters), a 10 AWG (American Wire Gauge) copper cable should suffice.

A 10 AWG copper cable is commonly used for Level 2 EV chargers in residential settings and can handle 240 volts and 32 amperes. It provides a good balance between cost, safety, and performance.

However, if your cable length exceeds the typical residential range, you might need a slightly thicker cable, such as an 8 AWG, to maintain the recommended voltage drop.

What Type of Armoured Cable Should You Pick?

Armoured cables come in various types, such as steel-armoured or aluminum-armoured. The choice of material depends on factors like cost, installation requirements, and the local environment.

Steel-armoured cables offer better mechanical protection, while aluminum-armoured cables are lighter and may be preferred in certain situations.

Additionally, you may want to consider the cable’s insulation type. Common types include PVC (Polyvinyl Chloride), XLPE (Cross-Linked Polyethylene), and EPR (Ethylene Propylene Rubber).

The choice of insulation depends on factors like temperature, environmental conditions, and local regulations.

Summary

It’s important to note that local electrical codes and regulations may vary, so it’s always a good idea to consult with a qualified electrician or follow any local guidelines for EV charger installations to ensure compliance with safety standards.

Additionally, some EV manufacturers may have specific recommendations for cable size, so it’s a good practice to check your EV’s manual or contact the manufacturer for any specific guidance.