Voltage drop and quality of video surveillance: 3 countermeasures

There are different indicators that affect the effectiveness of a video surveillance system. Today let’s talk about the voltage drop in the cable line of CCTV equipment. How to determine the voltage drop on the camera resistance? What do you need to do to reduce the risk of voltage drop? Read the answers in this article.

What is a voltage drop? 

The length of wire from the CCTV camera to the DVR affects voltage quality. A long cable reduces the voltage. The voltage drop has two significant disadvantages:

  • it degrades the quality of the resulting image;
  • it reduces the operating reserves of equipment for video surveillance.  

The increase in voltage consumption depends on the increase in resistance of the camera. When the voltage drops, it causes an increase in power consumption.

The article “Can video cameras work without electricity? Top 3 Solutions” might be informative for you.

Cable resistivity formula

When choosing video surveillance equipment, consider the importance of selecting the right cable. Wire specifications from the manufacturer can help determine the resistance of your cable.  

The voltage drop in the cable is affected by the resistance. This is clearly seen in the formula: 

U of the cable = I of the camera * R of the cable, where 

R – resistivity, ohm/m;

U – voltage, V;

I – power consumption, mA.

To calculate the resistivity of the cable, use the following expression:

R=p*L/S, where

S – wire cross-section, sq.mm.

L – length of wire, m;

p – conductor resistivity.

From the formula, you can see that thin and long wire gives more resistance. Selecting the wiring according to the optimal cross-section will keep the voltage in it.    

When will voltage problems start? 

First of all, the voltage is affected by the connection of the infrared illumination. The resistance in the mains changes. This in turn affects the resistance of the video camera. Each camera has a different voltage level. The surveillance camera starts to consume more power, thereby reducing the cable voltage. And this lasts until the minimum voltage is reached on the camera.

Determining the optimal voltage value for the power supply and observing this indicator in the system operation will allow the camera to switch easily from the night mode to the day mode. The calculated voltage reading will be retained and the quality of the video surveillance will not deteriorate.

3 countermeasures

There are three ways to counteract or avoid voltage drops in the cable:

  1. Using a heavy-duty power supply. The cable must have a large cross-section. The power figures depend on the results obtained after calculating the level of voltage drop.     
  2. Using a video camera with the optimum voltage. The lower limit is 10V.
  3. Location of the power supply close to the camcorder. PSU allows you to adjust the voltage.

Read the article “Complete list of expenses for home video surveillance“.

Simple video surveillance format

An affordable and simple video surveillance system is offered by Faceter. Smart video surveillance of good quality, analytics for business, facial recognition, and other smart features are offered by Faceter. The user chooses the set of necessary functionality. Updating is automatic, only the owner has access to the cloud archive at any time from anywhere in the world.

A pair of smartphones and Faceter software is enough to equip a video monitoring system at home, for example. The choice of tariffs allows you to use cloud video monitoring even for free.   


Modern technologies are evolving exponentially. Artificial intelligence and computer vision are no longer new concepts. Due to market growth and demand for video surveillance installation not only for businesses but also in private homes, video monitoring applications are improving. With Faceter you will always be aware of events at your surveillance object online, including for 0 rubles.

Александр Вебер

Alexander Weber

Specialist in video surveillance, video analytics, cloud storage systems. Consultant on the integration of video surveillance systems and tools in various business sectors. Over 10 years of industry experience.

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