Installation guide: proper grounding methods and best practices for Wireless configuration

Author: Salvador Bertenbreiter November 19th 2009


This guide will explain you the steps you must follow for a proper installation of Ubiquiti equipments in outdoor environments. It also covers basic Wireless configuration through the Web GUI, for a strong and reliable link.

The examples are based on a Nano M5, in any case, the procedure is nearly the same for all AirMAX and 802.11a/b/g series (Nonetheless, for 802.11a/b/g equipments, you must upgrade the standard PoE power supply included in the box with a PoE adapter providing earth grounding/ESD protection, such as Ubiquiti’s PoE-15 or PoE-24). NEVER USE a PoE adapter with an output voltage of more than 24volts, or else you will fry your device. The extra grounding recommendations were taken from WHT posts in the UBNT forum, thanks to WHT for that.

A proper grounding installation will prevent most ESD problems, such as a dead Ethernet chip, some device instabilities and auto-rebooting. In any case be aware that there is no such thing as protection against a direct strike by lightning.

Proper grounding installation

Requirements

Requirements for AirMax equipments

Outdoor FTP cable
  • The device to be installed
  • FTP or STP outdoor Cat. 5e cable (for under 30 meters of length you can use the included PoE-15 adapter, when a cable which length of over 30 meters is required, you must use the PoE-24 adapter) pre-crimped with RJ45 shielded plugs (recommended). Never use a UTP cable for outdoor installations, because then your devices would not be protected against ESD.

If you want to crimp the cable by yourself, you also will need the following:

  • At least two RJ45 shielded connectors
  • A RJ45 crimper tool

Requirements for 802.11a/b/g equipments

  • Same as for the AirMax series, but also replace the PoE power supply included by a a PoE adapter providing earth grounding/ESD protection, like the Ubiquiti PoE-15 or PoE-24).

Steps

Steps when using FTP/STP cable pre-crimped w/ RJ45 shielded connectors

  • Install the device (in our example a Nano M5) in a pole or tower, using the Plastic Straps included in the box. Make sure you have a clear LOS (Line of Sight) between the devices to be connected. This applies for both Point-to-Point and Point-to-Multipoint links, since it is a key requirement for a strong and stable wireless link. In some cases, you may establish a nLOS (Near Line of Sight) link, it isn’t recommended, but in case this is your only option remember that 2.4GHz waves have “better penetration” through walls and trees than 5.8GHz waves.
  • Connect the RJ45 shielded connector to the Nano M5 (or your respective device) RJ45 female port. Then close the Nano’s cover.
  • Hold the cable to the pole using plastic straps, using one strap every 60-90cms.
  • Connect the other side of the cable (also by using a RJ45 shielded connector) to the PoE adapter in the port labeled “POE”.
  • Connect a standard UTP or FTP cable between your Router or switch and the PoE adapter in the port labeled “LAN”.
  • Finally, connect the power cable to the PoE adapter. Make sure your electrical system is properly grounded. If the power supply system of your home/office/tower does not have proper grounding, none of the previous steps will be good to prevent ESD problems.

Steps using FTP/STP cable crimped by yourself

  • Install the device (in our example a Nano M5) in a pole or tower, using the Plastic Straps included in the box. Make sure you have a clear LOS (Line of Sight) between the devices to be connected. This applies for both Point-to-Point and Point-to-Multipoint links, since it is a key requirement for a strong and stable wireless link. In some cases, you may establish a nLOS (Near Line of Sight) link, it isn’t recommended, but in case this is your only option remember that 2.4GHz waves have “better penetration” through walls and trees than 5.8GHz waves.


  • See this section to learn how to crimp an UTP cable guide. You may skip it if you already know. The only difference between crimping an UTP cable and a FTP cable is that the second one has a small wire under the foil. This wire (preferably 2cm longer than other wires) should be wrapped around the outside of the shield when installing the shielded RJ45 plug. It is very important to have direct contact between the foil and the shield of the RJ45 connector.
  • Connect the RJ45 shielded connector to the Nano M5 (or your respective device) RJ45 female port. Then close the Nano’s cover.
  • Hold the cable to the pole using plastic straps, using one strap every 60-90cms.
  • Connect the other side of the cable (also by using a RJ45 shielded connector) to the PoE adapter in the port labeled “POE”.
  • Connect a standard UTP or FTP cable between your Router or switch and the PoE adapter in the port labeled “LAN”.
  • Finally, connect the power cable to the PoE adapter. Make sure your electrical system is properly grounded. If the power supply system of your home/office/tower does not have proper grounding, none of the previous steps will be good to prevent ESD problems.

Other recommendations (quoted from this WHT post) for extra grounding protection are as follow:

    - Try to extend some metal at least a foot above the NS to serve as a "preferred strike point" for lightning and ground that puppy.
    - Use a grounded Ethernet protector just before the spot where it enters the building.

In my opinion, the above measures are not really necessary for standard installations, but if for any reason, you wish some extra protection, that is how it works.


Recommended Wireless configuration for a strong and reliable link

Thanks to the simplicity of AirOS and Ubiquiti equipment with integrated signal LEDs, to run a multi-km wireless link has become really easy (Provided you have a clear LOS and normal interference levels). You may check this article (http://www.ubnt.com/wiki/index.php/How_to_bridge_internet_connections) to learn how to do a point-to-point link.

But in most cases, to achieve maximum performance and stability you will need to carry out some precision settings. There is no unique set of pre-established parameters for a reliable “all scenarios” link. Sometimes, you will need to play with two or more parameters combinations to obtain a strong link. However, there are a few hints that can help:

  • Disable the ACK Timeout Auto Adjustment.



  • For point-to-point links, set the “Distance” (it automatically adjusts the ACK Timeout value) to 125% of link distance in both devices. 125% is not a binding value, only a recommendation. In some, you may get better performance using 110% or 115%, just try different values.
  • For multipoint-to-point links, set the “Distance” on the AP to 125% of the farthest client distance. For the Stations (CPE), set the “Distance” on each Station to 125% of the AP to this client’s distance. Again, 125% is not a binding value, only a recommendation.
  • If your link’s environment has much interference, then try changing the Channel. If this doesn’t improve your performance or stability, try reducing the Channel Width to 10MHz (remember, that will make your network invisible for most, if not all, WiFi devices of the standard, but not for Ubiquiti devices).





  • You can check your Client Connection Quality, CCQ, on the device’s Main Page.
  • My last one recommendation is that you use strong Wireless Security; I recommend the use of a WPA2-AES. You can read more about Wireless Security in the AirOS Manual.