Grounding of PTP820S and PTP820C Radio installation

We have people asking do we need LPU for PTP820S and PTP820C installation. This paper will address those concerns.

PTP 820S and PTP820C includes built-in surge protection for its Ethernet and power interfaces. PTP 820S’s surge protection implementation complies with surge immunity standard IEC 61000-4-5 level 4. For the area where there is no severe lighting, there is no need for addtional LPU as long as the grounding is done properly during the instalaltion. More details about grounding will be covered later in the paper.

In areas in which severe lighting conditions are likely to occur, it is strongly recommended to add additional protection by placing lightning protectors on all electrical Ethernet cables, near the connection points with the PTP 820 unit.

The recommended LPU for PTP820S or PTP820C is  "C000000L033A  Gigabit Surge Suppressor (56V)"

Now let's focus on how to do the grounding properly. The following picture shows proper tower grounding:

1. For customers using optical (SFP) cables, no grounding is required.

2. For customers using Ethernet cables, grounding is critical.

2a. To ensure proper grounding, the Ethernet Cable RF-45 plug must be shielded with a crimping tail.


2b. For PTP820C and PTP820S installations Cambium highly recommends the following CAT5E cable : "N000082L016A PTP 820 CAT5E Outdoor 100m drum".  The preparation of cable and correctly crimping the RJ-45 connectors is critical in the field.

2c. The Ethernet cable should be  grounded every 50 meters using Ethernet Cable Grounding kit. " N000082L017A PTP 820 Grounding Kit for CAT5e F/UTP 8mm cable"

grounding kit.jpg

2d: On the front of each PTP 820 radio unit:

- Loosen the nut, plain washer and serrated washer from the GND stud, using the metric offset hexagon key and the wrench.

- Place the cable lug (supplied with the grounding kit) on the screw.
- Secure the cable lug.
- The second side of the GND cable should be connected to the main ground bar or terminal ground bar of the site.
- Perform a resistance test between the 2 lugs of the GND cable. Verify that the result is 0-2 ohms.

Note: The unit’s grounding screw terminal is permanently connected to protective earth in a building installation in accordance with applicable national code and regulations by a service person.
A 2-pole circuit breaker, a branch circuit protector, suitably certified in accordance with applicable national code and regulations, rated maximum 20A, shall be installed for full power disconnection in a building installation.
Any outdoor antenna cable shield is permanently connected to protective earth in a building installation.