
How to calculate volt drop
Apply your own customisations to the generated PDF certificates, such as the default certificate colour and even the default pen ink colour.
- Enter the load value in Amps.
- Enter the supply voltage.
- Enter the cable length.
- Select a cable type.
- Select the phase (single phase / three phase).
- Calculate
Volt Drop Calculation Example
- Load: 32 Amps.
- Supply voltage: 230V.
- Cable length: 15 meters.
- Cable type: Flat twin and earth.
A Flat Twin & Earth 6.0mm² volt drop mV/A/m = 7.3, so 7.3 x 32 Amps x 15 meters / 1000 = 3.5 volts.
Online Volt Drop Calculator
Give this free online voltage drop calculator a go, or download the app.
Volt Drop Regulations
525.1 – In the absence of any other consideration, under normal service conditions the voltage at the terminals of any fixed current-using equipment shall be greater than the lower limit corresponding to the product standard relevant to that equipment.
525.201 – Where fixed equipment current-using equipment is not subject of a product standard the voltage at the terminals shall be such as not to impair the safe functioning of that equipment.
525.202 – The above requirements are deemed to be satisfied if the voltage drop between the origin of the installation (usually the supply terminals) and a socket-outlet or the terminals of fixed current-using equipment does not exceed that stated in Appendix 4, section 6.4.
Source: BS 7671