John Wooden once wrote, “It’s the little details that are vital. Little things make big things happen. I love these word because although I would never call the correct cable selection for an installation a little thing, it is a vital choice, most don’t give it much thought."

This affects the operation of the installation as a whole, it has a direct impact on the installations life span, it directly impacts the components used and most importantly WILL impact safety and the safety of those around it. It can mean life or death!!

I have tried to explain this in a simple way, based on the diagrams presented. This little experiment had quite an impact on me in its ability to get the point across.

As displayed in (Fig 1) we have a very simple experiment illustrated in the schematic. We will use this diagram to discuss load, the effect this has on current flow and in turn on our cable and by extension components. We will the see how this will affect the life span and operation of our installation and thus why cable selection is so imperative and not the place one should look to cut costs.


What we see here in (Fig 1) is a circuit with a Cell (Power Supply), going through a Switch and on through a Light Bulb (this will serve as our indicator) and finally through a Fan before we complete the circuit.


As now illustrated in (Fig 2) use your finger to apply pressure to the fan. This represents load. Observe the effect on the light bulb (indicator). The bulb will get brighter and brighter as you exert more and more pressure. This indicates that more current is being pulled through the system.

What effect will this have?

Put simply the extra current causes the cable to heat up and creates extra heat in the entire installation. PVC cables in general are made to run at 70 degrees Celsius. If the cable selected is on the border or perhaps slightly under the required specification for the installation and any other possible factors like ambient temperature, radiant heat from other cables or components, the cable can run over the specified temperature. This causes the plasticizers used in the PVC to exhume to the surface making the cable age quicker as the sheath becomes brittle and in severe situations can crack.

Note too that if the cable sheath cracks due to this incorrect use/selection of the cables it can cause arcing and thus be a danger.

Cable selection is a vital part to any installation and Alvern Cables has a well-trained team ready to assist in this process.