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).
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).
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.
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.