The power over Ethernet (PoE) technology makes the installation of IP camera system simple. The single Ethernet cable can transmit both power and data to the IP camera. There is no need to deal with AC power sources at the edge. Where the cable reaches, the power and data arrive. Usually, each IP camera requires an independent cat5e/cat6 Ethernet cable. Sometimes, we may want to add a new IP camera at the scene to cover more areas. Re-wiring Ethernet cables could be a challenge especially while the construction is completed. Is there any plausible way to add the new IP camera without re-wiring the new cable? Firstly let’s take a quick look at the basic concept of PoE technology.
The Power over Ethernet (PoE) employs the twisted pairs to transmit power as well as data. The fast network (100mbps) only needs half of the twisted pairs (12-36) to transmit the data, which leaves another half of the twisted pairs (45-78) unused. At the very beginning, the PoE takes the spare pair (45-78) to send the power in parallel to the edge device. However, this solution only can provide fast network (100mbps). The 1000mbps network requires all 4 twisted pairs to send the data. Thanks to the development of technology, both data and power can go through the same twisted pairs. The splitter will separate the power from the data at the edge. Eventually, most of the PoE Switch can use the same twisted pair (1236) to transmit the power and data. If it is the 1000mbps network, the 4578 will be used to transmit the data as well. There is always power loss during transmission. As the twisted pair is so thin, the power loss becomes more serious. DC48V-DC55V is being used to inject to the twisted pair. The maximum power budget is 25.5W (PoE+) at the edge. This design guarantees the remaining voltage will be higher than 36V at the edge within 100 meters (328ft).
We may still need to understand the difference between 100mbps and 1000mbps networks. The 100mbps requires half of the twisted pairs and 1000mbps requires all the twisted pairs. What if we move half of the twisted pairs from 1000mbps? The 1000mbps network is backward compatible to 100mbps and it will downgrade to 100mbps automatically. As most of the IP cameras only need less than 10mbps, the fast network (100mbps) will be more than enough to carry a single IP camera. Now the most straightforward solution comes up to add the camera without wiring the new cable. We can reuse half of the twisted pair (45-78) to send to a second IP camera. As most of the IP cameras only support a 100mbps network. There is no difference after you move half of the twisted pairs from the existing cable.
What you will need is the passive Ethernet cable splitter to re-organize the twisted pairs. The cable splitter will split the cat5e or cat6 Ethernet cable into two groups with the same sequence. There are two RJ45 ports at both ends. Now you can connect two cameras at the edge. Meanwhile, link two RJ45 ports at the other end to the PoE switch. The passive Ethernet cable splitter only re-uses the existing cable by taking the spare twisted pair. It can’t save the PoE ports at the backend. You will need a second PoE port to supply the new IP camera. If there are no extra PoE ports available, the PoE injector could be a handy tool to convert the non-PoE ports to a PoE port. As previously mentioned, we can use the Ethernet cable splitter to add a second camera, because we assume the power and data are being sent through the same twisted pair, we got half of the spare twisted pairs in the single cable. This may not be the case with some of the equipment such as PoE NVRs or PoE injectors. Some of the PoE NVRs and PoE injectors still use the spare twisted pairs to send the power in parallel which is being separated from the data, because the design is more simple. You will need to pick the PoE injector with data and power over the same twisted pairs (12-36), otherwise, this solution will not work for both old and new cameras. You can try to find the power pin from the specification of the POE injector or PoE NVR. The power pin needs to be 12-36 which is the same as the data pin. Most of the PoE Switch use twisted pair 12-36 for both power and data now.
The second solution is the 1-in-2-out PoE extender. Technically, the PoE extender is an outdoor PoE Switch. It doesn’t take leverage of the spare twisted pairs. Simply you have to hook up the PoE extender to the main network by using the existing Ethernet cable. You are going to have second standard PoE ports from the PoE extender. There is no power source required for the POE extender. The PoE extender will be powered by your PoE injector and PoE Switch at the backend. While you are using the 1-in-2-out POE extender to add a new camera, only the power budget needs to be considered. As you have split the PoE power, you may face the problem of insufficient power for new IP cameras. If your PoE Switch only supplies PoE (14.4W), the PoE Switch may fail to supply enough power for two IP cameras. The PoE+ (30W) can be used to supply the power to the PoE extender. The PoE extender is a plug-and-play solution. There is no need for configuration. It also will not compromise the bandwidth. The bandwidth is still 1000mbps while it works with a 1Gpbs switch. With 1-in-2-out PoE extender actually you have expanded the PoE Network beyond 100 meters. Technically, you have 200 meters PoE from the edge device to the first PoE Switch. That is what the PoE extender stands for. One more thing to know is both PoE and non-PoE devices can be attached to PoE extender. The standard PoE will verify the edge device. If the edge device is a non-PoE equipment, the PoE extender only provides data without power. It is safe for standard POE to work with non-PoE equipment.
If getting one PoE port is still not enough, the PoE powered switch is another solution to increase the multiple PoE ports by using the single Ethernet cable. Working similarly as 1-in-2-out POE extender, the PoE Powered switch expands the PoE ports of up to 7. You can have 6 extra PoE ports. As the PoE powered switch is compatible with PoE++ (95W), which takes all 4 twisted pairs to send the power and data. As a result, there is 71W power budget from the PoE Switch. It is enough to power 7 IP cameras or other non-PoE equipment.
