Low Voltage Lighting Cable Selector

This calculator will help you determine the minimum required cable size and the corresponding voltage drop for your electrical installation.

No suitable cable found for the given parameters.

Caution - for Guidance ONLY

NO guarantee as to the accuracy of these values is given. And they should be checked against some other source.

Where ever possible the transformer should be mounted near the light fitting, BUT not within 9 inches to protect the transformer from heat damage and to reduce the cable size required from the transformer to the light fitting.

When wiring 12v fittings either single or together, it must be remembered that lower voltage means higher current, (e.g. 1 x 50W 12v lamp alone requires 4.2 AMPS).

Therefore, the conductor size of the cable between the transformer and the fitting is larger than that used in 240v lighting circuits.

Due to the possibility of voltage drop, the correct choice of cable is vital. Undervolting by more than 0.6v reduces the efficiency, affects the colour of the light and may affect the lamp life.

The calculator above will help you make the correct choice of cable.

DO NOT lay under or encase the cable or transformer with roof insulation

Supplying more than one lamp from a single transformer can result in significant volt drop between lamps if wired in parallel, causing non uni-form illumination across the run of lamps. To overcome this we recommend using the IB FS020 fused splitter or a multi-outlet transformer.

Each lamp supply is protected by an anti-surge fuse which prevents the transformer output from being dragged down in the event of a short circuit in any one of the fittings

Note: The actual cable size and runs required to connect several lamps to the same transformer output must be equal to or greater than total load of the run

Allowances MUST be made for operating temperatures outside the above, for correction factors refer to the full IEE 16th edition regulations for tables.