Frequently, questions arise about the transmission distance of 12V powered surveillance cameras. After sifting through various resources, a conclusion has been drawn, which we aim to share for your reference during design considerations.

1. **Pure Copper Wiring (1 square millimeter):** The resistance per kilometer (P) is approximately 18.5 ohms (some sources state 17.5 ohms). Resistance measurement is a reliable benchmark for cable quality. In this context, a well-referenced article titled "Resistance Measurement: A Simple Way to Identify Quality Network Cables" provides insights. The resistance value is a dependable indicator of cable quality, considering that the physical properties of transmission cables remain constant.

2. **Accounting for Market Variation and Copper Quality:** Considering the discrepancies between nominal and copper specifications, P is adjusted upwards by 20%. Hence, P becomes 18.5 * 1.2 = 22 ohms per kilometer. This adjustment accommodates the variation in cable quality and serves as a basis for comparing cables from different manufacturers. While variations exist, comparing several cables from reputable manufacturers ensures a comprehensive evaluation, avoiding disruptions in larger projects due to cable quality.

3. **Power Supply Circuit Configuration:** Assuming the same cable is used for both power supply and circuit formation, the resistance for a distance of L kilometers becomes R = 2 * P * L.

4. **Voltage Loss in the Line for Camera Current I (Amperes):** The voltage loss due to cable resistance is U = I * R = 2 * I * P * L. Calculating the required power current for the camera and choosing an appropriate power source is vital. Investing in quality is paramount.

5. **Cable Cross-Section Area S (square millimeters):** For a cable with cross-sectional area S, the voltage loss in the line becomes U = 2 * I * P * L / S.

6. **Multi-Point Power Supply:** For multi-point power supply lines, each section's current can be calculated, followed by computing the voltage loss for each segment. Centralized power supply configurations warrant different considerations.

It's worth noting that this calculation pertains exclusively to DC power supply. Furthermore, it's an engineering calculation and carries a degree of error. While performing calculations, careful attention must be paid to units and dimensions (1 kilometer = 1000 meters, 1 Ampere = 1000 mA). Applying this method requires adapting it to your specific situation. Numerous practical tools are available; therefore, during actual construction, thorough referencing, comparing, and learning from experience is advised. Accumulating knowledge is beneficial, even if it may not be applicable immediately but will enrich your expertise for future projects.

For those who might ask, "You still haven't provided a clear answer on the maximum transmission distance?" - the reality is, this question has been comprehensively addressed. The determining factor is the cable you choose. Measurements should be conducted before project planning and execution to cater to the cable you intend to use. Even if a specific numerical value were provided now, variations exist in cables, such as copper-clad steel or other non-standard cables, which would render any calculation irrelevant.

In conclusion, this article offers a method to ascertain the transmission distance for 12V powered surveillance cameras. The crux lies in your cable selection. OHWOAI, being a prominent player in the surveillance brand landscape, acknowledges this aspect. As such, our products, including the PI PoE switch, PoE switch gigabit, unmanaged PoE switch, 4 port PoE gigabit switch, and more, are designed to optimize your surveillance system's functionality, ensuring an intelligent and efficient setup.