Choosing the correct cable gland size is one of the most important steps in electrical installation. However, many users are unsure how to match cable size with the right gland for cable. Because of this, wrong selection is very common in industrial and panel applications.

If the cable gland size is too large, sealing becomes weak. On the other hand, if it is too small, the cable can get damaged. Therefore, understanding the correct method is essential.

This guide explains how to select the right cable gland size using cable size, diameter, and practical steps. In addition, it focuses on brass cable gland selection, which is widely used in industrial applications.

Why Cable Gland Size Matters?

A cable gland is not just a fitting. Instead, it performs multiple important functions. It seals the cable entry, holds the cable firmly, and protects against environmental conditions. Because of this, the correct cable gland size ensures:

• Proper sealing and ingress protection.
• Strong grip on the cable.
• Protection from dust and moisture.
• Safe earthing in armoured cables.
• Long service life.

Moreover, using the wrong gland for the cable can lead to leakage or system failure. Therefore, correct selection should never be ignored.

Understanding Cable Size and Cable Diameter:

Cable gland size refers to the metric thread size of the gland body, which corresponds to the cable’s outer diameter. The most common metric sizes include M12, M16, M20, M25, M32, M40, M50, and M63. Choosing the correct size depends entirely on the outer diameter of your cable.

For example, an M20 brass cable gland typically accommodates a cable with an outer diameter ranging from 6mm to 12mm. Consequently, if your cable falls outside that range, you need a different size. Always measure the outer sheath of the cable before ordering, not the conductor size or insulation diameter.

Here is a quick reference to guide your selection:

• M12 — Cable OD: 3–6.5 mm
• M16 — Cable OD: 4.5–10 mm
• M20 — Cable OD: 6–12 mm
• M25 — Cable OD: 10–17 mm
• M32 — Cable OD: 15–21 mm
• M40 — Cable OD: 19–28 mm
• M50 — Cable OD: 28–38 mm
• M63 — Cable OD: 34–44 mm

These ranges may vary slightly between manufacturers. Therefore, always consult the manufacturer’s datasheet when specifying a gland for cable entry in critical installations.

Step 1: Measure the Cable Diameter

The first step in selecting the correct cable gland size is measuring the cable diameter. You can use:

• Vernier caliper
• Measuring tape
• Cable datasheet

Make sure to measure the outer sheath. Do not guess the value. Even a small mistake can affect the selection. Because cable thickness varies, actual measurement is always better than assumptions.

Step 2: Identify the Cable Type

Next, identify the type of cable you are using. This step is important because different cables require different gland designs. Common cable types include:

• Armoured cable.
• Unarmoured cable.
• Control cable.
• Instrumentation cable.

For armoured cables, the gland must also grip the armour properly. Therefore, a double compression brass cable gland is often preferred in industrial applications.

Step 3: Match Cable Diameter with Cable Gland Size

Once you have the cable diameter, the next step is to match it with the correct cable gland size. Each gland has a clamping range. This range defines the minimum and maximum cable diameter it can hold. For example:

• M20 gland → 6–12 mm cable diameter
• M25 gland → 10–18 mm cable diameter
• M32 gland → 15–22 mm cable diameter

Therefore, always choose a gland where your cable diameter falls within the range. This is the most reliable method to select the right gland for the cable.

Step 4: Use a Cable Gland Size Chart

A cable gland size chart makes selection easier. It connects cable size, cable diameter, and gland size. For example:

• 3 core 10 sq mm cable → approx. M20 or M25
• 4 core 25 sq mm cable → approx. M25 or M32

However, these values are only references. Because the actual cable diameter may vary, always confirm with measurement. Therefore, charts are helpful but should not replace actual checking.

Step 5: Consider Installation Conditions

Even after selecting the cable gland size, you must consider where the gland will be used. Important factors include:

• Indoor or outdoor installation.
• Exposure to moisture or chemicals.
• Vibration or movement.
• Hazardous environments.

Because of these conditions, material selection becomes important. A brass cable gland is widely preferred because it offers corrosion resistance and durability.

Why is the Brass Cable Gland Preferred?

A brass cable gland is one of the most commonly used options in industrial applications. It is preferred because:

• It resists corrosion
• It provides strong mechanical strength
• It ensures good electrical conductivity
• It performs well in harsh environments

Therefore, most industrial projects choose brass over other materials.

Cable Gland Accessories and Their Role:

Selecting the correct cable gland size is only part of the process. Accessories also play an important role in installation.

Common cable gland accessories include:

• Earth tags for grounding.
• PVC shrouds for protection.
• Locknuts for secure fixing.
• Washers for sealing.

These accessories improve safety and performance. In addition, they help maintain proper sealing and electrical continuity.

Common Mistakes to Avoid:

Many users make mistakes when selecting a gland for a cable. However, these can be avoided with a basic understanding. Common mistakes include:

• Selecting based only on cable size.
• Ignoring cable diameter.
• Not checking clamping range.
• Using an incorrect gland type.
• Mixing incompatible accessories.

Because of these mistakes, installations may fail. Therefore, always follow proper selection steps.

Choosing the Right Cable Gland Manufacturer

Apart from selecting the correct cable gland size, choosing the right manufacturer is also important. A reliable cable gland manufacturer and supplier ensures:

• Accurate clamping ranges
• Consistent quality
• Precision machining
• Availability of accessories

Volt Metal Industries is a brass cable gland manufacturer and exporter from India. The company supplies cable glands for both domestic and international markets. In addition, it offers CE, RoHS, and ISO certified products suitable for industrial applications.

Conclusion:

Selecting the correct cable gland size does not have to be complicated. Start with your cable size, measure the outer diameter, and match it to the appropriate metric thread. Then choose a brass cable gland with the right IP rating and clamping style for your application. Finally, complete the assembly with the correct accessories for a fully sealed and mechanically secure termination.

For product enquiries, technical specifications, or export quotations, visit us at:

 www.voltmetalind.com

 info@voltmetalind.com

 +91 9879332240