How to Choose the Right SWA Cable: Size, Armouring, and Voltage Explained

Steel Wire Armoured (SWA) cables are a popular choice for electrical installations that require ruggedness, mechanical protection, and safety. They can be found in industrial settings, commercial buildings, and even outdoor or underground power distribution. The role of SWA cables is to provide electrical power consistently even in the harshest of environments.

Nevertheless, it is not as easy as it looks to pick the correct SWA cable. One has to be careful because a wrong selection can cause the conductor to get overheated, a voltage drop, a shorter lifecycle, or, worst of all a major safety hazard. In this article, you will learn how to select the right SWA cable based on the essential three criteria: cable size, armoring, and voltage rating as explained by SWA Cable Suppliers.

What Is an SWA Cable?

SWA cables as per SWA Cable Manufacturers are power cables that have been given an additional layer of protection in the form of steel wire armoring. The steel wires act as a shield and thus help to prevent the cable from being damaged by force, pressure, or other environmental components.

An SWA cable usually has the following elements:

• Conductors (usually copper or aluminium)
• Insulation layer
• Bedding
• Steel wire armour
• Outer sheath

Because of this tough design, SWA cables are perfect for places that have to deal with moisture, soil, vibrations, or one of those scenarios where a cable is more likely to get damaged accidentally.

Why It Is Crucial to Choose the Right SWA Cable

Choose the correct SWA cable and you get:

• Power transmission that is safe
• Electrical performance that is efficient
• Electrical standards compliance
• Service life that is extended
• Maintenance and repair costs that are reduced

The problems, such as overheating, a breakdown of insulation, voltage drop, or inefficiency of the system, are just some of the outcomes when an incorrect or an undersized cable is used. Conversely, choosing excessively sized cables without a justifiable reason only ramps up the expenses without giving you any extra advantage.

Choosing the Right SWA Cable Size

Typically, cable size means the cross-sectional area of the conductor, which is mostly measured in square millimetres (mm²). Installation of the wrong size cable can be very dangerous, as it would not be able to carry the current safely.

1. Current Carrying Capacity

One of the most important factors to consider when selecting the size of a cable is how much load current is going to be drawn. In fact, the size of the cable should be such that it can handle the maximum load current without the cable temperature going beyond the safe limits.

• The total electrical load connected
• Continuous vs intermittent load
• Future expansion requirements

Ensure that you never operate a cable at its maximum rating; carry out all the necessary precautions, such as allowance of safety margin.

2. Voltage Drop Considerations

Every conductor wire has a certain resistance. When electrical current passes through the wire, voltage drop takes place due to the resistance of the conductor. The loading of the equipment will be reduced and the equipment will even get overheated if the voltage drop is too high.

• Cable length
• Conductor material
• Cable size
• Load current

If the distance of the cable run is quite long, then you will probably have to increase the size of the cable to ensure the voltage at the load end is within the acceptable limit.

3. Installation Method

Basically, the way the cable is installed, besides the place it is installed at, greatly determines the heat dissipation of the cable and therefore affects its current carrying capability (ampacity).

• Buried underground
• Laid in ducts
• Installed on cable trays
• Fixed to walls

The truth of the matter is that cables that are installed underground or are put inside the closed spaces may warrant bigger sizes given the limited capability of heat dissipation.

4. Ambient Temperature

At higher ambient temperatures, the cable will not be able to get rid of heat effectively because the temperature difference that Drives the heat flow will be smaller. In other words, if a cable has to be installed in hot surroundings, then derating factors come into play, meaning a bigger cable size than normal will be required.

Understanding Armouring in SWA Cables

Armoring has been the primary feature of SWA cables and it is through armoring that the cable has been able to give mechanical protection and, at times, electrical earthing.

1. Purpose of Steel Wire Armour

Steel wire armoring is one of the ways the cable withstands harsh environments, and it is through armoring that the cable is able to:

• The main role is to prevent the cable from being damaged by external forces such as impact and compression.
• Helps the cable to stretch without breaking when the cable is being pulled in.
• Also serves as the fourth wire and the earth in certain situations.

On the other hand, given these advantages, SWA cables are still very much in demand for outdoor, underground and industrial applications.

2. When Armouring Is Necessary

Cables should be armoured in the situations and conditions where they are:

• Directly buried in the soil
• Exposed to physical/mechanical impacts
• Located along areas with heavy pedestrian and vehicle traffic
• Deployed in industrial or construction sites with high level of activities

Armoring is a great idea if extra safety measures need to be taken for indoor or protected installations, though it may not always be mandatory.

3. Single-Core vs Multi-Core SWA Cables

Cable sheath can be done differently for various cable types:

• The outermost layer of multi-core cables is usually made of steel wire armour.
• Normally single-core cables have aluminium wire armour so as not to get the magnetic heating effect.

Choosing the right armoring type is both a safety and security decision.

4. Earthing Considerations

In many instances, it is possible and likely that the cable armour itself is used as the protective earth conductor. There are, however, several factors that influence this, such as the cable size, installation method, and local electrical codes. If the armour is being used for this, make sure that the earth continuity is adequate.

Final Thoughts

It is a great challenge to choose the right steel wire armoured cable, which is also the one that the installation and utilization environment, armoring, and voltage are all taken care of properly.

By deciding on the right cable size, the most suitable armoring, and the proper voltage level, you are guaranteeing an electrical installation that is safe, efficient, and durable.

An SWA cable that is properly chosen, apart from giving protection against mechanical damage and weather conditions, will make sure that the load is kept constant and that the safety standards are met. Therefore, if you allow a reasonable amount of time for proper cable selection, you will come to realize that it is a very important stage in every electrical project because it diminishes the risks, operating costs, and time of non-availability of the system.

Also Read: What Is Type 275 Cable? Complete Guide to Uses, Standards, and Performance