Grounding Grounding Grounding

This is my personal thread to share practices that have served my WISP well
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sirhc
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Grounding Grounding Grounding

Sat May 27, 2017 11:35 am

On direct strikes (tower hit) no, grounding will probably not save you but most damage to WISPs is not from direct strikes, or ESD (near strikes). Most damage is from ground current and sometime static discharges.

Ground current is the #1 cause of damage to WISP equipment and proper grounding and bonding all grounds together will most definitely save you.

Making sure electrical service ground rods are bonded to tower ground rods is VERY IMPORTANT. In fact making sure the Electrical service ground rod is in good condition each spring, corrosion free and TIGHT in the ground. If you have less than 2 ground rods on the electrical service add a second bonded to the first at least 4-6 feet away and if you have 2 ground rods and either are loose add a 3rd.

I also go to the pole where the transformer is and add a second ground rod there as often the utility company simply set a short ground rod in the same hole while setting the pole which is useless. Come a few inches off the pole and drive in a 5/8" 8-10 foot ground rod. Strip the #6 copper insulation off the wire coming down the pole to their ground rod and use a split bolt to secure #6 copper wire to your new ground rod with a copper acorn.

ESD is rare but Static and ESD protection is handled the same way. Make sure you run a #2 green wire up the tower from your tower's main ground bus bar at the base of the tower to an insulated ground bus bar near your antennas and then run #6 green to each antenna mount.

Make sure all ground wires run down hill never uphill, pretend they are pipes and if you put water in the top and make sure the wires would drain empty.

Static builds up on the antennas when wind blows across them at just the right humidity or dew point which is what happens in the spring, summer, and fall as it is normally hot and a cool front comes in and temperature drops rapidly with high winds which when the dew point hits the right amount huge amounts of static are generated on the tower and that static charge will look for a path to ground and you do not want the path chosen to be your Ethernet cable. This is another reason to always want a 10' or more service loop on your Ethernet cable at the top so the cable path is longer and less attractive than the intended ground wire path. This is also the same type of protection to help with ESD but as I said ESD is rare but people constantly confuse ESD and or storm damage with ground current and static damage.

Money and time spent on grounding is money and time well spent
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abdoudia
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Re: Grounding Grounding Grounding

Sat May 27, 2017 3:30 pm

How would ground antennas that have no ground lung like Ubnt Rockets ?

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Re: Grounding Grounding Grounding

Sat May 27, 2017 3:41 pm

A Rocket is not an antenna, it is just a radio. The antenna that you connect to it is grounded to the mast through the clamp. The radio is grounded to the antenna through the coax. The radio is also grounded through the ethernet cable both through the FTP foil drain and through the PoE neutral.

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Re: Grounding Grounding Grounding

Sat May 27, 2017 4:00 pm

A UBNT Rocket has DC negative bonded to chassis or earth ground.

This would be the outside of the SMA jumper cable that connects the radio to the antenna.

The antenna is connected to the tower and this DC negative in the Rocket is bonded to the antenna that is bonded to the tower that is connected to the ground rods.

Now a NanoStation and NanoBridge is insulted inside a plastic chassis and has no access to tower Earth Ground.
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Re: Grounding Grounding Grounding

Sat May 27, 2017 4:50 pm

So if I understand correctly no need to add the #6 ground cable to the Antenna since its connected to the tower that is already grounded?

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Re: Grounding Grounding Grounding

Sat May 27, 2017 5:07 pm

abdoudia wrote:So if I understand correctly no need to add the #6 ground cable to the Antenna since its connected to the tower that is already grounded?


I have no idea what language you are reading in but NO WHERE DID I SAY THIS.

Look electricity will take the path of least resistance until the current taking that path increases that paths resistance (heats up) to where the next path is now less resistance and the excessive current will now take the secondary path and so on and so on.

Here are some good posts on grounding:
viewtopic.php?f=30&t=1816
viewtopic.php?f=30&t=188
viewtopic.php?f=17&t=1786&start=30#p13447
viewtopic.php?f=30&t=1429

Simple questions to test your common sense ability:
1) Which is a better conductor with less resistance COPPER or STEEL?

2) Is your tower and mounts all one piece of steel or all welded together to become one piece or is it made up of many pieces of galvanized and or painted steel bolted together?

3) Does a joint where steel is bolted together make a good conductor of electricity or does the paint and many years of corrosion create resistance at very joint of your tower?

Now that you have answered the basics here is one final question to see if you have any common sense:
Pretend you are a charge of energy built up on your antenna and or mount and you are seeking the path of least resistance to Earth Ground.

Would you think the STEEL tower with its many sections bolted together where each joint is painted and corroded over the years has less resistance than your Ethernet COPPER wire that uses gold plated connectors at each junction to get to Earth ground?

If you were an electrical charge which path would you take?

If after reading and taking the above quiz you still think that you do not need a dedicated copper ground wire running up your steel tower to a ground bus then to each antenna mount then best of luck to and be ready for many tower climbs over the years to replace equipment.

Look at the bright side, it is a good cardio workout.
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Re: Grounding Grounding Grounding

Sat May 27, 2017 7:10 pm

Maybe I was not clear on my question,

I have round wire running on all my towers with #6 wire connected to Radios Like Airfiber, Mimosa,SAF where there is a ground lung.

what i want to know is the proper way of grounding a sectorial antennas or a PowerBridge M10 , since they do not have a ground lung.

Should drill a whole on the mount and screw in the ground wire ?

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Re: Grounding Grounding Grounding

Sat May 27, 2017 8:07 pm

No, Nanostation, NanoBridges, PowerBeams are isolated from the tower inside their non conductive plastic chassis and it's best to leave this way.

If you run a ground wire from your ground bus to the mount that a sector, dish, or any radio is mounted to you are providing a path for ESD or static charges to follow to ground instead of seeing the Ethernet cable as the best less resistant path to ground.

Even though a Nanostation is isolated in a plastic chassis if the static or ESD charge is large enough it "can" arch through the plastic but once again if the mount is grounded chances of this happening is greatly decreased.

Make sure:
electric service ground rods are in good condition and maybe add another
tower ground rods are in good condition
consider adding a ground rod to utility pole transformer
electric service and tower ground rods are properly bonded
you have a dedicated #2 ground wire running up tower to ground bus near radios and #6 wire to each mount that holds a radio.

All of these practices are spelled out in crayons in the posts I provided above.
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Re: Grounding Grounding Grounding

Sat May 27, 2017 8:16 pm

Everything is clear now thanks ! :hurray:

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Lightning rod/Grounding question

Mon Sep 03, 2018 3:38 pm

Hi Chris,
We are located in Panama, where lighting strikes in rainy season are an almost daily occurrence. Our towers are about 100' high, and we have a lightning rod at the top of the tower. It is connected to a #4 or #6 cable that goes all the way down and is bonded to our grounding array. The grounding array usually consists of a 30' diameter ring of 4/0 copper cable encircling the tower base. It is exothermically welded to a minimum of 3 grounding rods.

This grounding array is also bonded to the service ground of the electrical service, and the ground of any related equipment (Netonix, power supply or charge controller etc...). We use RFArmour connectors and Ubiquiti ToughCable in order to ensure a grounding path from radio to Netonix, then to ground. We will be implementing your solution of grounding the radio antennas at the top of the tower, but should that be bonded to the lightning rod
/ground cable? Are we risking sending energy through our equipment as it is apparently all tied together.

Is this a good idea? We are still losing lots of equipment, both radios, and as you know, switches.

In some cases we have moved to solar in order to isolate ourselves form utility-based surges, this has worked well so far, but we still lose equipment.


I understand all too well that a direct lightning hit is usually something we can do little about.

thanks for all your help.

Al

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