Unsure which cable size to choose for your wiring job?
Here are some easy steps you can take to make sure!
1. Find out the voltage
Start off with the Voltage the fitting is operating at. 240V? 12V? 110V?
2. Find out the total wattage
Next, work out the total number of Watts drawn (e.g. quantity of light bulbs x their wattage).
E.g. A light with 3 arms each with a 60 watt light bulb has a total wattage of 3 x 60W = 180 Watts
Getting this info will enable you to work out the Amps drawn by the fitting in Step 3.
3. Calculate the current
To calculate the Current (in Amps) drawn by a fitting, divide the Power (in Watts) by the Voltage (in Volts).
E.g. using the example above, 180 Watts / 240 Volts = 0.75 Amps.
4. Work out the conductor size
Now you know the Current, you can work out the cable conductor size you need from the table below. In our example, we know we need a cable rated safely above 0.75 Amps. So, for decorative lighting, 0.5mm (3A) or 0.75mm (6A) is usually sufficient.
Current Ratings for Flexible Cables
|Conductor Size, sq mm||Max Current, amp|
A mains-powered (240V) heater rated at 3000 Watts.
This draws a current of 12.5 Amps. (3000 divided by 240)
From the table above, it will need 1.5 sq mm flex.
A mains-powered (240V) light bulb rated at 100W
This draws a current of 0.4 Amp (100 divided by 240)
It will need 0.5 sq mm flex.
A 12V circuit of 20 LED bulbs, each rated at 3W
This draws a current of 5 Amp. [(20 multiplied by 3) divided by 12]
From the table above, it will need 0.75 sq mm flex.
I hope this has been helpful - if you have any queries please contact us.