What type of cable do I need?

Selecting the right type of cable for your electrical system is important from both a safety and performance perspective. Cable that is low quality or not designed to suit the application it is being used in can lead to breakages, poor connections, and poor equipment performance. The following guide includes a list of considerations you should make when selecting cable.

Purchase cable from a reputable supplier

It is strongly recommended that you purchase high quality cable from a reputable supplier. This can reassure you that the cable ratings are genuine and that the cables comply with the Australian Electrical Standards. Purchasing cable from a reputable supplier can also help protect you in the event of a cable failure or recall.

Match cable to the application

Not all types of cable are suitable for every application. There are three categories of cable you will encounter when shopping for your electrical system: auto, marine, and domestic.

Auto cable is used for most DC circuits and will probably be the best for fit for your electrical system because of its reliability, flexibility and durability. Its availability in a wide range of sizes and colours make it ideal for connecting various electrical appliances.

Marine cable is similar to auto cable, but it is usually tinned to prevent corrosion. In some instances, marine cable might also have a sheath that is rated against damage by oil and diesel when used in engine rooms. The extra protection provided by marine cable typically makes it slightly heavier, more expensive, and less flexible than auto cable.

Domestic cable should be reserved for AC wiring only. If your electrical system has an AC component to it, make sure that your domestic cables have a minimum of 7 strands. This is because cables that use a solid core or only a few strands of wire are not designed for the vibrations faced by mobile power systems and are not compatible with the crimps used in DC cable termination.

Confirm cable specifications

You will need to confirm that voltage and temperature ratings of the cables you are using suit your application. These values are typically based on the construction of the outer sheath of the cable and are typically printed on the cable (see the image below).

Voltage ratings are normally shown with two numbers. The first number is represents the voltage rating of the insulation to ground and the second number is the voltage rating from one insulated conductor to another insulated conductor. In the case of the Tycab cable below, the rating is 0.6/1kV, which means the cable is insulated to ground up to 600V and insulated to another insulated cable up to 1000V. These values far exceed the voltage you would see in most off-grid installations, but it is still good to confirm that they are listed.

Temperature ratings are typically shown as mix of letters and numbers. The Tycab cable shown below is rated to V90HT. A full list of temperature ratings and their meanings can be found in the Australian Electrical Standards.

Environmental contact ratings are the final consideration to make when selecting cable. In a caravan with composite paneling, you should confirm your cable is rated for contact with polystyrene. In a marine environment, you should confirm that your cable is resistant to oil/diesel, especially when used in an engine room. You can confirm this information with your cable manufacturer.

Match the insulation colour to the circuit

The colouring of your cable insulation or heat shrink should also be consistent to ensure that your system is safe, easy to install, and easy to troubleshoot. The standard cable colouring code is as follows

The DC negative on most installations will be black, with the exception being some marine installations where yellow is used to avoid confusion with the AC neutral wires. It is also common for black cable to be used for the positive and negative cables on DC installations, with red and black heat shrink used to differentiate between the two. To simplify installation and maintenance, you might also consider labeling the ends of cables with text to help identify them.

Summary

There is a lot to consider when determining what type of cable should be used. Generally speaking, high quality cable purchased from a reputable manufacturer, such as Tycab, should meet the needs of most off grid electrical systems. Enerdrive also carries a range of pre-cut and terminated cable kits, which are suitable for installing a wide range of Enerdrive products.