Lightning Suppressors

So I’ve read over the previous threads and searched for this topic. I’ve found a few hits and quite a bit of good information. I also referred one of my superiors to the threads and he ordered some of the equipment.

I’m not sure if what was ordered is 100% correct or not. This is what we’re trying to do and the problem we’re having…

We have our CMM Micro wired using shielded cable to this: … tegory=337 and from this to our access points at the top of the tower. When I do this all the AP’s boot up correctly, etc. except they randomly drop off…different intervals, no patterns, etc. they randomly lose power and their “link” lights on the CMM will turn off until they reboot and re-establish connection.

We also ordered a: (Model #RRDN4543A) - 8-port Surge Prot 1-POE/1-GPS box and 6 POE Surge Prot Cards (1 backup). It is my understanding that this box is mounted to the top of the tower and the AP’s are powered through it. However - when we did this…we had the exact same problem with AP’s randomly dropping off the map in no order, with random time intervals.

I just want to make sure of two things:

1) We have the correct equipment
2) We’re doing this right, lol.

I have been reassured of both but the first CMM box scares me. The details seem right but the name with GPS/CMM2/CMM3 kind of scares me.

Just wondering how long your grounding cable is; if it is >= to the length of your cat 5 you are hindering the grounding capability of your surge suppression system.

With your AP’s rebooting, make sure you have them set to revieve timing, I have seen AP’s reboot or become inactive when they multiple AP’s on a CMM generate GPS sync, it causes errors as there are now up to 8 GPS signals ( 6 AP’s and 1 or 2 backhauls ).

The proper way to config this from tower would be to have it in this order;

Radios: AP / Backhaul -> CMM3 Surge Suppressor Box -> CMM2
GPS: GPS -> Surge Supprssor / Grounding -> CMM2 GPS Radio Card

Double check your APs to make sure that they are recieving GPS signal from the CMM, best thing is to log into them and make sure they can see at min 3 to 4 satellites.

If this is happening to all the AP’s I would start looking more at the CMM2 being you cause, it is rare that 6 APs fail at a tower and do the exact same thing.

By and chance did you have a lighting strike, or brown out that would affect the CMM?

One more thing;

If this installation got hit by lightining and you had to replace everything; did you replace the GPS cable?

Also did you replace the cables going from the AP’s down to the surge suppressor, or did you just reuse them; If the previous equipment took a lightining strike and fried I have seen cat 5 cable fuse together if there was too much voltage running through the cables. Good way to check; if the pins on the cat 5 ends had any scorch marks on them, if it is a short run which it sounds like it’s under 30 feet, replace the cat5 cable; good idea to use shielded on this as well.

Well to be honest we reused the cable for both the GPS and the access points. The AP’s work perfectly fine -until- you hook in either of the surge suppressor boxes. The grounding cable is less than a foot. The cat5 cable is 4-5 ft. When you first hook the box up…everything appears fine. Walk away for a few hours and I notice on my intermapper that my AP’s have been dropping in random orders…and sometimes it’s every 30 seconds…othertimes it’s once every 20minutes.

However, they do not drop off at all if you have them hooked straight into the CMM Micro

All AP’s are set to receive power on the power port. AP’s are getting sync from satellites as well.

Bump - Anyone have any ideas?

The only thing I can think of is the since we reused the cable from the AP’s down it could be a problem but I would think if it works fine normally…doesn’t make sense not to work with the suppressors, yes?

Do you have other RF kit on the tower or another tower close by…

Try something for me, take the APs from the tower and bring them to ground level use the same cable (if possible, if not attacch a new long cable), see if the problem is happening at ground level, and then start hoisting the kit up and see if the problem starts when you get to a certain height…

I had this problem at a tower which had alot of RF.

It has the same problem on the ground.

Also it’s a POE llightning suppressor - what does that have to do with RF?

what if you take it back to the office… and try it there… do you have a different CMM/ different GPS module…

I do - yes. I can’t take my current AP’s down though…and I don’t have a spare AP to test it with on a different CMM/GPS

I’m baffled.

I think the surge protector is messing with the timing sync…

Me too - I just don’t get why it works for everyone else and not for me, heh.

blame it on Murphy…

as a test take off the grounding cable so the surge protectors are NOT grounded… see if the problem persists…

Yeah I think that’s the next logical step. The problem is I have to order some AP’s first to test with.