WS-6-MINI Keeps crashing/rebooting?

[sirhc]

I am not sure what to say, you would think we would have seen the voltage fluctuating like your describing when we test them on the bench before we serialize them?

Also seems like pretty high odds that if there was a few defective units that somehow got past our testing that you would end up with 3?

We have seen this several times helping customers and every time it ended up being a poor grounding issue especially where the electric service was not bonded properly to the tower creating a ground potential difference between the tower and the electric service which pushes excess current through the switch and damages the switch because the bond between the tower grounding and service grounding is now the Ethernet cables since there is not a heavy gauge wire bonding them.

Please post up some pictures of your tower, box, and grounding system, would loke to see your gounding system:
Service grounding rods
Tower grounding system and rods
The bonding wire between the service ground rods and the tower grounding system.

[6gnet]

I haven't had the time to get pics posted but here are few things we noticed after inspection of all towers with minis:

1. One tower has electrical service ground connected (AWG6), no tower ground at all, voltage goes down to 43V and up to 48V but runs stable with 3 sectors and 1x af5x. The PoE cable is not shielded......no surge protector installed on it. PoE cable goes to 12 port netonix switch which is fine.
2. Second tower has electrical service ground only (AWG6), no tower ground at all, voltage goes down to 43V and up to 48V with 1 sector and one rocket ac lite, upon addition of second sector, switch freezes. The PoE cable is not shielded..... no surge protector installed on it. PoE cable goes to 12 port netonix switch which is fine.
3. One switch with voltage going up and down straight from the box... can't explain this one... both in the lab and on the tower it's acting like the above two.
3. Other towers with service ground only, voltage stable, switch stable, all ethernet cables are shielded...

Looks like the lack ethernet cable shielding even when the grounding is OK may cause problems with minis, we will make sure we have surge protectors on non-shielded cables (sometime replacing the cable is not possible).

Can anyone suggest surge protectors that would work from 60V up or so ? Ubnt surge protectors are 90V and up which I assume is too much for minis ?

One question comes to mind: if 12 port netonix switch is connected with mini with unshielded cable, how come the 12-port switch is OK while mini is having these freezing issues (which means they were damaged due to surge or other event)?

[sirhc]

All I can say is towers must be bonded to electrical service ground, this bonding should be #2 wire or better.

If supplying AC power to a tower from more than 25-30 feet then do not bring the Earth ground and use the tower grounding rods as Earth Ground.

Once the MINI is damaged from a ground potential differnce it is done for and will never work properly again.

Read this page
http://www.cablinginstall.com/articles/ ... pment.html

[sbyrd]

All I can say is towers must be bonded to electrical service ground, this bonding should be #2 wire or better.

If supplying AC power to a tower from more than 25-30 feet then do not bring the Earth ground and use the tower grounding rods as Earth Ground.

Once the MINI is damaged from a ground potential differnce it is done for and will never work properly again.

Read this page
http://www.cablinginstall.com/articles/ ... pment.html

[6gnet]

I can say for sure there was no ground potential difference as the only grounding was to the electrical service ground (both mini and the 12port switch in the building). We've measured 0.05 ohms (assuming the ohm meter is ok) between the end of the ground cable on the roof and the grounding copper bar in the building. No other grounding is available on these buildings. Out of 4 identical setups, 2 with FTP ethernet cables seem to be working ok with switch having stable voltage and not freezing and 2 with non-shielded (UTP) cables have had issues and this is why I'm assuming it must have been caused by surges.

Since we cannot replace these ethernet cables (brick building, cables in the wall, not replaceable) what else would you suggest ?

Here's a drawing showing how it's all connected:

-G

[sirhc]

Well if your diagram is to scale and I am sure it is not but if your ground run in green is longer than your Ethernet cable in blue (which is why you normally would put in an Ethernet service loop to insure your Ethernet cable run is longer than your intended ground wire run) then Static or ESD surges would still use your Ethernet cable run to get to Earth ground which would be through your switches.

[6gnet]

It's not to scale, ethernet is longer for sure (there's about 6ft service loop at the bottom of the pole) then the grounding cable and the grounding cable is quite thick (14mm2 which is about AWG6) comparing to ethernet. Still I can suspect that ESD might have caused it since the 2 buildings had UTP cables and these are the ones that have issues now hence the question about surge protectors. Ubnt surge protector has discharge lamps that start working at 90V, is this good enough for the mini or do we need something more sensitive ?

-G

[sirhc]

It's not to scale, ethernet is longer for sure (there's about 6ft service loop at the bottom of the pole) then the grounding cable and the grounding cable is quite thick (14mm2 which is about AWG6) comparing to ethernet. Still I can suspect that ESD might have caused it since the 2 buildings had UTP cables and these are the ones that have issues now hence the question about surge protectors. Ubnt surge protector has discharge lamps that start working at 90V, is this good enough for the mini or do we need something more sensitive ?

-G

I wish I could answer that question for you but I have ZERO experience with Ethernet Surge Protectors and do not have a single one in my entire WISP network which is 15 towers and over 750 devices. I have only lost 1 radio on a tower due to surge damage and that was from Sprint removing the grounding wire when they left the tower which I talk about in my one grounding post under SIRHC'S CORNER here on the forums. I did lose equipment from direct tower strikes and the last one of those was over 4 years ago and they were DIRECT STRIKES as one blew a light off the tower and the other blew a cell carriers panel off the tower and killed a ton of turkey buzzards that called the tower home.

viewtopic.php?f=30&t=1429

BUT I DO HAVE SOME KICK ASS GROUNDING SYSTEMS!

[sirhc]

By the way we can repair those WS-6-MINI's for $75 each if you want them repaired.

We put new boards in them.

[6gnet]

I wish I could answer that question for you but I have ZERO experience with Ethernet Surge Protectors and do not have a single one in my entire WISP network which is 15 towers and over 750 devices. I have only lost 1 radio on a tower due to surge damage and that was from Sprint removing the grounding wire when they left the tower which I talk about in my one grounding post under SIRHC'S CORNER here on the forums. I did lose equipment from direct tower strikes and the last one of those was over 4 years ago and they were DIRECT STRIKES as one blew a light off the tower and the other blew a cell carriers panel off the tower and killed a ton of turkey buzzards that called the tower home.

viewtopic.php?f=30&t=1429

BUT I DO HAVE SOME KICK ASS GROUNDING SYSTEMS!

I did read your post few times before and I do agree that proper grounding is a must. We've had our share of issues due to improper grounding (on one occasion grounding cable was there but not connected anywhere in the building). I assume you ran only FTP cables on that tower ? I've also seen a difference between regular FTP cable and the carrier FTP cable from Ubiquity during high winds on a really tall tower (cables are 95m long each). We now use only the carrier FTP cable from ubnt on that tower especially that it's got TV and FM antennas (our antennas are on a 120m (393ft) level, while TV/FM atennas are around 300m (985ft) level). No surge protectors there at all and we did have 2 direct lightning strikes recently that did not effect antennas or the WS-10-250AC that we have there.

On these smaller buildings on the other hand, with pre-ran UTP external ethernet cable, we have to come up with a working solution so minis don't die on us. I can take a hit (by hit I mean connectivity will break) during high winds or near by ESD for as long as it does not damage the mini. WS-xx-250AC seem to be unaffected during the time when the mini goes bad on the same building.

Perhaps Netonix can improve the PoE input on them by using 70V discharge lamps or other solution that would help at least not damage the mini. I will try to put the ubnt surge protector once I replace one of the minis and see if it helps. The question is will mini handle up to 90V ESD or is it also too much ? I tested these protectors and they do seem to start shorting at around 83V to 91V (3 out of 5 around 83V).

-G