Re: [AFMUG] Question on APC Arresters

Mon, 20 Mar 2017 18:30:07 -0700

There really is no good answer because there is no way to know where destructive impulses may be coming from. Too many surge suppressors can interfere with the data. I would say one on the circuit is generally good enough. If it is not good enough two probably would not be good enough either.
Many of my customers put them on both ends. That is OK as long as good grounding principles are followed. But if you have a large difference of potential in the grounds, two surge protectors can actually cause problems. 


-----Original Message----- 
From: Jerry Head

Sent: Monday, March 20, 2017 7:08 PM
To: [email protected]
Subject: Re: [AFMUG] Question on APC Arresters

So, at the risk of sounding none-too-bright (which might be accurate in
my case), is placing a SS on both ends of the Ethernet cable be the
recommended course here? I.E. Switch---SS---Ethernet up the
tower---SS--radio?
Both SS grounded to earth ground via #2 copper going up the tower?

On 3/20/2017 7:50 PM, Faisal Imtiaz wrote:

Netonix. Toughswitch. Tycon. Anything that isn't AF and is passive PoE 
blows.

That would be an in-correct statement or an in-correct assumption at best.


Most passive switches have some-sort of over load protection built into 
them. The question of how fast they react would be a valid one.




Matt you have to keep in mind that most equipment damage is not due to the 
'short' but due to the current flowing in the wrong direction..





Regards


Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 x 232

Help-desk: (305)663-5518 Option 2 or Email: [email protected]

----- Original Message -----

From: "Chuck McCown" <[email protected]>
To: "Matt Hoppes" <[email protected]>
Cc: [email protected]
Sent: Monday, March 20, 2017 7:58:53 PM
Subject: Re: [AFMUG] Question on APC Arresters

You never know which direction the surge is coming from, many times, 
perhaps
most times,  it comes from the power lines and originates in the NOC 
gear.
And with a piece of CAT 5 going in and out of a surge protector, you 
never

know what the surge protector is connected to.  A surge protector is

essentially a piece of CAT 5 or a CAT 5 coupler with a few extra 
components.

There really is no direction to them or a "tower side" to them.


I could  fuse all 8 wires.  And have double surge suppressors.  Or just 
put

surge on one side and label it "tower".


How do you detect the direction of a nanosecond rise time pulse?  You 
would

have to have an RF reflectometer on each of the 8 wires tied to some fast
logic.   You would want sub microsecond switches that open the CAT5 and

logic to figure out where the pulse comes from and send it where?  If it 
is

a powered wire on the POE where do you want that connected to during the
pulse?


All surge suppressors I have ever seen do things essentially the same way 
I

do things.

In any event, I will post this to the group.  Perhaps there is a learning
opportunity for me here.  Like to see if others have seen their POE blow
when shorted.  I personally have not seen this before.

-----Original Message-----
From: Matt Hoppes
Sent: Monday, March 20, 2017 5:46 PM
To: Chuck McCown
Subject: Re: Question on APC Arresters


I'm not sure what the better option is. Not clamp on the power side, 
isolate

and clamp on the tower side only?


So a surge comes in, break the connection between ground and tower and 
only

shunt tower side to ground.


Honestly we were extremely surprised to find these did anything on the 
near

side of the unit. That came as a shock.

Netonix. Toughswitch. Tycon. Anything that isn't AF and is passive PoE
blows.


On Mar 20, 2017, at 19:29, Chuck McCown <[email protected]> wrote:

So, what would you have a suppressor do?  Not clamp to ground?
I  have not run into POE switches that will blow if shorted.  They are
energy limited.
What kind of switch?

-----Original Message----- From: Matt Hoppes
Sent: Monday, March 20, 2017 4:28 PM
To: Chuck McCown
Subject: Re: Question on APC Arresters

So the problem we are running into is the suppressor fires and clamps
which shorts the power supply on the switch, which kills the switch
port.  Now I'm out both a switch port and a suppressor.... I'm not sure
what I've gained.

River Valley Internet
"We Never Forget You Have a Choice"
570-433-7070 x 700


On 3/20/17 6:13 PM, Chuck McCown wrote:
Yes, they are clamping the wire.  So think of most of our devices as 8
individual surge suppressors.  They will short the impulses to ground.
If (as is common) the impulses come in on all 8 wires at the same time,
all 8 wires are connected to ground and as a result they are also
connected to each other.

-----Original Message----- From: Matt Hoppes
Sent: Monday, March 20, 2017 4:06 PM
To: [email protected]
Subject: Question on APC Arresters

Hey Chuck...  was discussing your Ethernet arresters last night.

Is it normal operating mode for them, when they take a strike, to go
into a "short circuit" situation on both sides of the Ethernet port?
























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