The term ‘Voltage Drop’ relates to the amount of voltage loss that occurs through all or part of a circuit. This is a result of increased resistance which is a measure of the opposition to current flow in a circuit, measured in ohms (Ω). Electrical cables of any size and length carrying current always present resistance. Although it can affect the entire circuit, it is first apparent at the end of a cable run. A simple comparison would be a garden hose, where the pressure of water running through it reduces the further away it is from its source. The 4 main factors which contribute to voltage drop are cable length, wire temperature, wire material and the cross sectional area. Generally, 12V lighting systems can withstand a maximum voltage drop of up to 8% (1V) with no noticeable effects, on the basis that the correct cable / power source is used and it is within range of the LED lamp voltage. If significant voltage drop does occur, it can cause dim lighting, strobing or no power at all.

To reduce the risk of voltage drop, consider the following:

• Reduce cable runs – keep length to a minimum with no more than 12 fittings per circuit
• Highly conductive wire, e.g. copper. A tinned end can improve performance and longevity
• Use high quality, heat resistant rubber cable. Minimum H05RN-F
• Use thicker cable where possible (1.5mm² / 2.5mm²) with a secure, watertight connection

For a larger garden where this is not possible, consider laying a mains power feed to various points / areas where additional 12V transformers can be installed to create separate, smaller circuits. 240V fittings can also be connected to the mains feed if required.

Suggested maximum cable run includes cable supplied with each fitting, adaptors and connector cables. Where longer cable runs are required, use thicker cable such as 1.5mm² / 2.5mm² which have a lower resistance and reduce voltage drop. Cable runs can be increased by up to 50% (approx) when thicker cable is used.

For longer cable runs, thicker cable is recommended. The below table is for 1.5mm and 2.5mm 2 core cable.

The above tables are a guide only. We strongly recommend that the voltage is checked with a volt meter at each fitting prior to final placement. Some external factors can affect performance, such as placement of cable etc.