We Value Your Privacy

We and our partners use technology such as cookies on our site to personalise content and ads, provide social media features, and analyse our traffic. Click below to consent to the use of this technology across the web. You can change your mind and change your consent choices at anytime by returning to this site.

Update Consent
Loading ...

How to Calculate the Voltage Drop for Street Lighting

Updated February 21, 2017

Voltage drop is a phenomenon in which the voltage through a circuit is converted to heat within the conductive material due to resistance within that material. Though voltage drop is of little consequence within a home or structure, it often comes into play when devices such as street lamps are powered several meters from a home or building. These large runs of conductive wire provide increased resistance that results in more voltage loss due to heat. Voltage drop can lead to improperly powered equipment or devices and in some cases may provide a safety hazard due to excessive heat within the conductive lines.

Loading ...
  1. Determine the resistance within the conductive material being used to supply the street lamp with power. These resistances are standardised and well known for the commonly used gauges of wire and are listed within the National Electric Code for easy reference. This resistance is given in terms of ohms per foot.

  2. Determine the voltage level to be used by the street lamp.

  3. Multiply the intended length of wire by the ohms-per-foot rating for that wire. This is the resultant overall resistance within the circuit wire.

  4. Multiply this resistance by the current within the wire. The current within the wire is dictated by the circuit to which the wire is connected in the breaker box of the building that connects the street lamp to the electrical grid. The resultant product is the estimated voltage drop within that specific run of cable.

  5. Tip

    If the voltage drop is excessive a larger, lower gauge wire, may be used to reduce the ohms-per-foot resistance and allow for a lower current to be used.

Loading ...

About the Author

Gabriel Dockery

Gabriel Dockery began writing in 2009, with his work published on various websites. He is working toward a Bachelor of Science in neuroscience in a transfer program between Ivy Tech College and Indiana State University.

Loading ...
Loading ...