28/05/2026
Are You Losing Power Before It Even Reaches the End of the Cable? ⚡
Voltage drop is one of those things that catches people out on longer cable runs, and by the time you notice the problem (dim lights, motors running slow, equipment behaving oddly), the installation is already done. Getting your calculations right before you pull the cable saves a serious amount of time and money.
The key factors to work through are the cable length, the current the load will draw, and the cross-sectional area of the conductor you're using. Copper cable is the go-to for most domestic and commercial jobs thanks to its conductivity, but on longer runs, sizing up is often necessary to keep voltage drop within the BS 7671 limit of 3% for lighting and 5% for power circuits. The installation environment matters too. Outdoor or underground runs will typically call for armoured cable, which has different resistance characteristics you'll need to factor in. Getting this wrong doesn't just affect performance, it can create compliance issues on your next inspection. 🔌
Have you ever had to re-run a cable because the voltage drop wasn't accounted for first time round? Or are you currently working out the right cable size for a longer run and not sure where to start? Drop your questions below. Our team has over 200 years of combined industry experience and we're happy to help you get it right from the start.
https://www.powerdiscount.co.uk/