Lightning arresters?
William P.N. Smith
router to a remote AP (even with PoE, so there's no ground loop
problems) can damage the APs, so I'm looking for some CAT5 lightning
arresters that are compliant with PoE.
Does anyone have any experience with, or preferred vendors of such
things? I've got a _lot_ of Google hits that I'm looking over, but
real-life experiences and personal reccomendations (or warnings) are
much better than manufacturer's literature.
My all-time favorite gear for antenna feedlines has always been
PolyPhaser, but I'm not sure how their CAT5 gear is...
Thanks in advance for any hints!
William P.N. Smith
>I'm looking for some CAT5 lightning arresters that are compliant with PoE.
Oops, just realized I have to specify that I'm looking for lighting
arresters that are compliant with 802.3af PoE _SWITCHES_, as midspans
and switches put their power on different leads...
Al Dykes
CAT5 Ethernet devices are isolated at each end good for a few thousand
volts (4kV ?). ISTM that if you get a lightning hit close enough to
exceed that you're screwed in lots more ways than your APs.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. Proudly then, even more so in hindsight.
William P.N. Smith
>CAT5 Ethernet devices are isolated at each end good for a few thousand
>volts (4kV ?). ISTM that if you get a lightning hit close enough to
>exceed that you're screwed in lots more ways than your APs.
Well, http://geekho.com/IMG_0140.JPG probably could have been
prevented (poor picture, but it blew the cover open) with some
appropriate lighting arresters. The (protected) antenna on the top of
the tower had been removed for replacement when this happened...
I'm looking at http://www.polyphaser.com/datasheets/NX4-60.pdf for
now, but they are pretty pricey, anyone have any other thoughts?
Thanks!
CWatters
"Al Dykes" <ady...@panix.com> wrote in message
news:e5dhhv$ijt$1...@panix5.panix.com...
> CAT5 Ethernet devices are isolated at each end good for a few thousand
> volts (4kV ?). ISTM that if you get a lightning hit close enough to
> exceed that you're screwed in lots more ways than your APs.
But that's only really intended to protect against differential earth
problems not lightening. I don't think even the "old" fat ethernet that used
cable piercing taps would survive very close lightening strikes. I don't
think that was rated for use between buildings that could be on different
mains phases.
Perhaps you need to investigate solar power for the remote end so that you
can use fibre and media converters?
William P.N. Smith
>Perhaps you need to investigate solar power for the remote end so that you
>can use fibre and media converters?
The 'remote end' is the other side of the house, where the cables go
to the pole on the roof. Antennas, weather station sensors, WebCam,
wireless internet node, don't need converters, just need arresters.
w_tom
protection that can be overwhelmed IF protection is not installed where
wire enters a building. Telephone switching stations connected to
overhead wires everywhere in town work uninterrupted and undamaged
during every thunderstorm. Operating without damage is normal and
necessary when protection is properly installed.
Protection is not the protector. Yes Polyphaser protectors are
legendary. But that is not because Polyphaser protectors do something
mythical. Protectors don't stop or block damage as a 2K or 4K NIC
interface must if missing is ... well what does Polyphaser discuss
extensively? Earthing is the protection. Polyphaser protector is
superb because (when) it makes a short connection to a same earth
ground used by AC electric, phone line, cable TV, and ham radio
equipment.
If transients are properly earthed at a building entrance, then that
2K or 4K volt protection in network devices is not overwhelmed. But
again, does PoE ethernet have that common mode transient protection? I
have not seen the numbers.
PoE means protector must remain well above that voltage (42 volts?)
BellCore specs in that Polyphaser protector (because phone lines were
generations ago direct lightning strike protected) define a low voltage
protector. Galvanic isolation inside that PoE ethernet device should
be sufficient to make any transient below those BellCore specs to not
be destructive. However I don't know if a PoE spec for voltage
transient means a lower voltage earthed protector may be necessary.
Contact Polyphaser for their interpretation. Get specs (numbers) from
those PoE devices to learn of their internal protection numbers.
Whereas conventional ethernet has that 2K or 4K volt galvanic
isolation, I don't know if that also applies to power wires in PoE.
BTW, why long before WWII did we suffer direct lightning strikes
without damage - and not use fiber optics? Direct lightning strikes
without damage is routine if the human does his job in advance. I just
don't know what internal protection numbers are for the PoE wires;
whether those BellCore numbers are sufficient..
William P.N. Smith
>Earthing is the protection. Polyphaser protector is
>superb because (when) it makes a short connection to a same earth
>ground used by AC electric, phone line, cable TV, and ham radio
>equipment.
Agreed! In this case, the wires from the roof come into one side of
the house (where there's a separate ground wire to a
lightning-arrester-only ground rod), and the computer gear is all
(lessee) about 100 feet of wire away. Not ideal, but we don't live in
an ideal world...
Fiber doesn't help because things like phone lines will also be on the
CAT5 cables, and those are more difficult and expensive to run over
fiber.
> PoE means protector must remain well above that voltage (42 volts?)
48V nominal, up to 52(?)V within spec. The switch/midspan thing just
means in my case that the data lines are only going to be clamped to
70(?) volts, not the 15(?) volts that they could use if the PoE
injectors were on dedicated "unused" pairs. I've found lots of
lightning arresters that only work on midspans, but only the
PolyPhasers that'll work with switches.
w_tom
about 70 volts on a 52 volt wire. Cat5 interfaces should be good for at
least 100 volts. But again, I don't have specific numbers. That's
not 100 volts continuous which is why protectors can earth such
tremenous transients.
Protectors are not filters. A filter does not provide effecitve
protection. Protectors are 'shunts' to earth. Protectors are best
when (for example) 50 meters from electronics. That separation between
a protector and transistor means better protection. A protector is
nothing more than a temporary connecting device (ie a switch) to earth.
A earthng connection that should be less than 3 meters, which is why
wires drop down to earth before rising back up to enter a building. A
connection that is better when 100 feet from transistors - not adjacent
to electronics.
Every incoming utility wire must use a common earth ground. No way
around that requirement since earthing - not a protector - is
protection. If CAT5 wire is earthed to a different ground, then
multiple earth grounds increase damage possibility. No way around that
common earthing requirement. Numerous solutions to fix the 'imperfect'
world from an Ohio utility is their 'good' solution. A 'preferred'
solution also demonstrated:
http://www.cinergy.com/surge/ttip08.htm
How do telcos install protection? Ideally a protector is up to 50
meters distant from switching computer transistors and near 0 meters to
a big, common, earth ground. IOW potectors on midspans don't really
accomplish much because they don't have that earthing connection common
to all other utilities..
William P.N. Smith
> http://www.cinergy.com/surge/ttip08.htm
Ah, that makes a lot of sense, I'll have the electrician run another
heavy wire between the lightning ground rod and the main power panel
to bond them together.
Should this bond wire go to the main power panel, or to the ground rod
for the main power panel?
Thanks!
CWatters
"William P.N. Smith" <news...@compusmiths.com> wrote in message
news:31fn729vp76e1j8rc...@4ax.com...
Try...
http://www.hyperlinktech.com/web/data_line_lightning_protectors.php
http://www.hyperlinktech.com/web/hgln_cat5-1.php
w_tom
accomplished and size of that bare copper wire. Earthing wire should
never be routed inside a building. Wires from each utility to those
earthing electrodes should be routed separate from all other wires (not
nylon tie wrapped together) so that earthing a transient does not
induce that transient on non-earthing wires.
Do not connect power panel to lightning ground electrode (the buried
rod). Lightning ground electrode and AC electric earth electrode
should be interconnected by a buried wire that makes them both a common
earth ground AND expands the earthing system. Interconnect the
electrodes. Do not ground a utility wire (telephone, cable TV, or AC
electric) directly to same electrode that is earthing a lightning rod.
Although both electrodes are interconnected, the distance from rooftop
lightning rod to AC electric box is longer; must first pass through
earth ground.
Bonding wire from AC panel to electrode should be routed 'less than
10 feet', no sharp bends, no splices, and not inside metallic conduit.
For example, some electricians will connect AC electric box by routing
an earthing wire up over foundation; exiting through wooden joists
instead of through concrete wall. Longer distance and more bends makes
earthing less effective. Earthing wire should, if necessary, pass
through concrete so as to exit above earth level; to shorten earthing
distance and to eliminate sharp bends. These requirements are beyond
what is demanded by code. These requirements make a protector more
effective.
William P.N. Smith
>http://www.hyperlinktech.com/web/data_line_lightning_protectors.php
Yeah, I know, but Hyperlink's definition of PoE is broken. They are
using _only_ the 'midspan' definition, where 1,2,3,6 are used for data
and 4,5,7,8 are used for power. Since I have a switch, I have phantom
power on 1,2,3,6, and since they state:
/*
The limits are +/- 15 volts on pins, 1, 2, 3 and 6 and +/- 58 volts on
pins 4, 5, 7 and 8.
*/
Their protectors would immediately go into conduction when the PoE
supply tried to turn on.
PolyPhaser seems to do it right, but of course they get ~$100 each for
theirs. I guess you get what you pay for... 8*}
CWatters
Use two cheap ones in parallel with some clever wiring? No forget I said
that :-)
Jeff Liebermann
<news...@compusmiths.com> wrote:
>My all-time favorite gear for antenna feedlines has always been
>PolyPhaser, but I'm not sure how their CAT5 gear is...
Drivel: Ever wonder what's inside a Polyphaser lightning protector? I
took apart an IS-PT50HN unit:
http://www.polyphaser.com/kommerce_productdetail.aspx?item=IS-PT50HN
About $70 retail or $18 used on eBay. Probably very sophisticated and
complex inside? Right?
Well... not exactly.
http://802.11junk.com/jeffl/pics/lightning/polyphaser-02.jpg
http://802.11junk.com/jeffl/pics/lightning/polyphaser-01.jpg
Sigh. I'm in the wrong business. The two parallel wires are a single
stage interdigital bandpass filter at 860-980MHz. It looks like 4
spark gaps in series. I guess that's so you get 4 lightning hits
before it totally shorts. The coil is to prevent grounding out the RF
signal.
Also, this is a friends lightning protection panel, where all his
antennas come together. It's not done yet. All the feedthru's and
boxes are lightning protectors.
http://802.11junk.com/jeffl/pics/lightning/panel.jpg
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 je...@comix.santa-cruz.ca.us
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Moe Trin
<ckuu729gom64jnsn9...@4ax.com>, Jeff Liebermann wrote:
>Drivel: Ever wonder what's inside a Polyphaser lightning protector? I
>took apart an IS-PT50HN unit:
> http://www.polyphaser.com/kommerce_productdetail.aspx?item=IS-PT50HN
>About $70 retail or $18 used on eBay. Probably very sophisticated and
>complex inside? Right?
Welll...
>Sigh. I'm in the wrong business. The two parallel wires are a single
>stage interdigital bandpass filter at 860-980MHz.
Yabbut designing interdigital filters is _hard_ work! Ya gotta go to
a technical library (or know where to buy ARRL books) and ya gotta use
mathematics!!! Then after your first design blows because you used
the wrong material for the circuit board, ya gotta try again!
NASA funded a program to act as a seed project for a "low cost" version
of a microwave landing system receiver for Gen/AV. The existing design
was from the high-price people, and the front end had three cavities
cast in AL, and a double balanced mixer. The winning "low cost"
design used microstrip, a 4 stage interdigital for the RF, and a 3
stage for the LO - the mixer was a single chip diode, and the
multiplier used to get the VHF output of the LO up to 4.8 GHz was
a Schottky diode used by the Japanese in UHF TV tuners. All of the
microwave stuff, including the antenna and a test coupler was on a
single 2 x 4 inch piece of G10. Total cost of the microwave parts
was under a buck. The assembly/test labor cost wasn't even that much.
(The high-price people spent more in tech labor costs tuning the
cavities, never mind the parts and assembly labor.) The "low cost"
house spent a bit more on the design - I think the final design was the
fifth iteration - but they'd recover it in production costs. Reading
some of the justification data they produced as part of the contract
was one he!! of an eye-opener for me. They were pricing components with
the costs to _four_ decimal places.
Old guy
John Navas
In <ccfk7252novr5guko...@4ax.com> on Sun, 28 May 2006 20:22:22
-0400, William P.N. Smith <news...@compusmiths.com> wrote:
<http://www.netgate.com/product_info.php?cPath=24&products_id=49>
Lightning Arrestor N-Male to N-Female $18
* Reliable Performance from DC ~ 3 GHz
* Voltage Rating: 90 Volt
* High Quality Construction
* Easily Replaced Gas Tube Element
* Multi-Strike Capability
* Bi-Directional Protection
* Protector will pass DC
* Mounting Bracket and Hardware Included
* 802.11b and 802.11g Compatible
--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>
William P.N. Smith
>William P.N. Smith <news...@compusmiths.com> wrote:
>>I'm looking for some CAT5 lightning
>>arresters that are compliant with PoE.
><http://www.netgate.com/product_info.php?cPath=24&products_id=49>
>Lightning Arrestor N-Male to N-Female $18
Gee, thanks, John. Should I use one per line on the CAT5 wire, with
the case grounded, or is there a way to use one per pair?
FWIW, I bought a few of these:
http://www.polyphaser.com/datasheets/NX4-60.pdf
To try...
John Navas
In <nvqa829ljsl9kj4o3...@4ax.com> on Tue, 06 Jun 2006 07:53:30
Sorry -- I missed the CAT5 part.
Polyphaser makes good stuff.
Here are some other options:
<http://www.hyperlinktech.com/web/data_line_lightning_protectors.php>
William P.N. Smith
>Here are some other options:
><http://www.hyperlinktech.com/web/data_line_lightning_protectors.php>
Is there an echo in here? Those don't work on (all) PoE
(configurations), though their ad copy pretends they do.