Contrary to popular belief, you do not need a surge suppressor to clamp so
close to the 'normal' voltage on the line.

Most well-designed products actually contain basic integral surge
suppression.  One of the most common questions I get is whether or not some
of my products contain surge suppression 'built in'.  I always answer no,
even though the answer is actually "absolutely".

Take for instance my SyncInjector products.  Every data line connected to a
connector goes through a surge suppression circuit before it touches the
rest of the circuit.  The power circuit for the injection has surge
suppression built in as well.   And so on.   BUT... this surge suppression
is meant to protect the device, not any connected devices, so when someone
asks if there's built in surge suppression I do answer as I said above - no.

The purpose of an external surge suppressor is to shunt any current away
that the device cannot handle through it's internal surge suppression
structures.   Most on-board suppression is designed for relatively low
voltages and/or currents.     Most devices will at least handle a very
short and low current 15kV pulse.  Beyond that it depends on the design of
the device.   The external surge suppression is needed to shunt away the
rest of the overvoltage - and for that whether it's 30V or 60V or more is
more academic than anything.  Yes, a 30V suppressor will likely protect you
better than a 60V one.  But the 30V suppressor is far more likely to fail
as well.

Personally, I just recommend a clamp voltage of around 60-100V for most
wisp usages.   With gigabit and four-pair power, anything else is just
asking for trouble.

-forrest

On Mon, Dec 1, 2014 at 11:49 AM, Matt Hoppes <[email protected]>
wrote:

> Maybe we're using different terms?
>
> I use surge arresters that clamp around 30 volts for my 24 volt devices.
>  Why would I use a 97 volt SA on a 24 volt device?
>
> On 12/1/14, 1:47 PM, Josh Luthman wrote:
> > Why?  You should always use HV.
> >
> > Josh Luthman
> > Office: 937-552-2340
> > Direct: 937-552-2343
> > 1100 Wayne St
> > Suite 1337
> > Troy, OH 45373
> >
> > On Dec 1, 2014 1:46 PM, "Matt Hoppes" <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> >     Standard for the regular radios.
> >
> >
> >     Matt Hoppes
> >     Director of Information Technology
> >     Indigo Wireless
> >     +1 (570) 723-7312 <tel:%2B1%20%28570%29%20723-7312>
> >
> >     On 12/1/14, 1:45 PM, Mike Hammett wrote:
> >     > Did you use standard or High Voltage surge suppressors?
> >     >
> >     >
> >     >
> >     > -----
> >     > Mike Hammett
> >     > Intelligent Computing Solutions
> >     > http://www.ics-il.com
> >     >
> >     >
> >     <https://www.facebook.com/ICSIL><
> https://plus.google.com/+IntelligentComputingSolutionsDeKalb><
> https://www.linkedin.com/company/intelligent-computing-solutions><
> https://twitter.com/ICSIL>
> >     >
> >     >
> >
>  ------------------------------------------------------------------------
> >     > *From: *"Matt Hoppes" <[email protected]
> >     <mailto:[email protected]>>
> >     > *To: *"Ubiquiti Users Group" <[email protected]
> >     <mailto:[email protected]>>
> >     > *Sent: *Monday, December 1, 2014 12:23:12 PM
> >     > *Subject: *Re: [Ubnt_users] airFiber Surge Arresters
> >     >
> >     > OK... so the TS *will* completely fry if you short one port.
> >     >
> >     > On 12/1/14, 1:21 PM, Seth Mattinen wrote:
> >     >> On 12/1/14, 10:05, Matt Hoppes wrote:
> >     >>> You short any PoE switch and normally you'll at least take out
> >     the port,
> >     >>> if not the entire switch -- in the case of a TS.
> >     >>
> >     >>
> >     >> A managed POE device should see shorts as an over current fault
> and
> >     >> shutdown the port. If it fries itself that's a poorly designed
> >     device or
> >     >> one that needs a fuse ahead of it and the fuse was omitted (i.e.
> >     why you
> >     >> put a fuse in front of a packetflux passive injector).
> >     >>
> >     >> I've accidentally shorted my share of POE connected cables either
> >     across
> >     >> pairs or to ground and none of the switches or injectors blew up.
> At
> >     >> worst they threw SNMP traps about overcurrent faults (manged) or
> blew
> >     >> the fuse (passive standalone). None were fatal to devices.
> >     >>
> >     >> ~Seth
> >     >> _______________________________________________
> >     >> Ubnt_users mailing list
> >     >> [email protected] <mailto:[email protected]>
> >     >> http://lists.wispa.org/mailman/listinfo/ubnt_users
> >     >>
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