| Author |
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Guest
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 Posted:
Wed Jul 20, 2005 11:07 pm Post subject:
Harsh Environment Cat5? |
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Hi,
I'm helping select a Cat5 cable for use in a new house on a small
island, which definitely qualifies as a marine environment. I've used
Belden Direct Burial Cat5 in this application before and it seems to
hold up well (except where the silicone grease has been wiped off the
ends of the wires and they have been left out in the sun), but I'd
like to check if there's something better available.
This is for inside a single dwelling, so it won't actually be used for
direct burial, but it's a really harsh environment and I'd like it to
last for many decades...
I'm assuming Cat5(e?) will be good enough for as far as I can see into
the future, and the builder really doesn't want to spend a ton of
money putting in (say) fiber in the hopes that he choses the right one
and it becomes useful sometime eventually...
Thanks! |
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Guest
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| Posted:
Thu Jul 21, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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Dale Farmer <dale@cybercom.net> wrote:
| Quote: | Pull in pvc conduit so cable can be easily replaced later.
|
Unfortunately, this isn't the way they wire houses here, it's all the
flexible conduit cast in cement, and I really doubt there'll be any
way to pull something new or replace it later.
I was thinking of dielectric grease around the connectors too. Would
I be better off with FEP cable insulation or 'direct burial', which is
essentially flooded with dielectric grease?
[Also, kinda of a rathole, but is it worth going to Cat5E, Cat5E+,
Cat6, or something else exotic, or is Cat5 really all that's required
to go all the way up to gigabit ethernet? I was getting all
interested in Belden DataTwist 600e till I found out it's
$752/1000ft!]
Thanks! |
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Dale Farmer
Guest
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| Posted:
Thu Jul 21, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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William, P., N., Smith wrote:
| Quote: | Hi,
I'm helping select a Cat5 cable for use in a new house on a small
island, which definitely qualifies as a marine environment. I've used
Belden Direct Burial Cat5 in this application before and it seems to
hold up well (except where the silicone grease has been wiped off the
ends of the wires and they have been left out in the sun), but I'd
like to check if there's something better available.
This is for inside a single dwelling, so it won't actually be used for
direct burial, but it's a really harsh environment and I'd like it to
last for many decades...
I'm assuming Cat5(e?) will be good enough for as far as I can see into
the future, and the builder really doesn't want to spend a ton of
money putting in (say) fiber in the hopes that he choses the right one
and it becomes useful sometime eventually...
Thanks!
|
Pull in pvc conduit so cable can be easily replaced later. regular cat
5 cable should be fine. By the time the cable has started to go south,
the wall jacks will have corroded and need replacing as well. You
can use some potting compound or dielectric grease to protect bare
metal in the back after you install it.
--Dale |
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glen herrmannsfeldt
Guest
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| Posted:
Thu Jul 21, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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William wrote:
(snip)
| Quote: | [Also, kinda of a rathole, but is it worth going to Cat5E, Cat5E+,
Cat6, or something else exotic, or is Cat5 really all that's required
to go all the way up to gigabit ethernet? I was getting all
interested in Belden DataTwist 600e till I found out it's
$752/1000ft!]
|
I believe that for a house, where you are unlikely to get near
the 100m requirement, that Cat 5 is fine for gigabit.
Cat5E has slightly better attenuation and related characteristics
which are length related.
My guess would be that Cat5 should be fine to about 80m, where
you would want 5E from 80m to 100m.
Though as far as I know, the gigabit standard was written
for Cat5 without the E.
Except for the price and how hard it is to install, DataTwist
is a pretty nice cable. Variations in wire spacing within the
pair cause variations in impedance which, over a long cable, mostly
increases attenuation. DataTwist has the wires in the pair bonded,
similar to the two wires in ordinary lamp cord, so the spacing stays
much more constant.
Two effects increase attenuation with frequency, skin effect and
impedance variations.
-- glen |
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J. Clarke
Guest
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| Posted:
Thu Jul 21, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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William P. N. Smith wrote:
| Quote: | Dale Farmer <dale@cybercom.net> wrote:
Pull in pvc conduit so cable can be easily replaced later.
Unfortunately, this isn't the way they wire houses here, it's all the
flexible conduit cast in cement, and I really doubt there'll be any
way to pull something new or replace it later.
dielectric grease
I was thinking of dielectric grease around the connectors too. Would
I be better off with FEP cable insulation or 'direct burial', which is
essentially flooded with dielectric grease?
[Also, kinda of a rathole, but is it worth going to Cat5E, Cat5E+,
Cat6, or something else exotic, or is Cat5 really all that's required
to go all the way up to gigabit ethernet? I was getting all
interested in Belden DataTwist 600e till I found out it's
$752/1000ft!]
|
Gigabit was designed around CAT5, but there were some requirements that
nearly all existing CAT5 met that weren't spelled out on the CAT5
standard--that's why CAT5E is "enhanced" instead of CAT6--it's CAT5 that
has been tested for the additional requirements. 5E is sufficient for
gigabit--it appears at this time that some higher grade will be required
for 10 gig. Still, if the environment is as harsh as you say, going to
CAT6 might give you a little more service life--if it starts with more
headroom then it should, all else being equal, take longer for it to
deteriorate to the point that it is no longer usable.
You might find <http://www.rjfield.com/> of interest.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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Guest
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| Posted:
Thu Jul 21, 2005 5:58 am Post subject:
Re: Harsh Environment Cat5? |
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glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:
| Quote: | Except for the price and how hard it is to install, DataTwist
is a pretty nice cable.
|
There's a tool at
http://www.newark.com/productimages/standard/3765751.jpg for only
$6.82 for splitting the pairs apart, I had assumed that that tool and
the usual punch-block 110 tool would be all I'd need for installing
the cable.
I've guesstimated the longest run is about 150 feet, maybe I'll dive
back into the Belden catalog for Cat5e-ish DataTwist FEP cable...
The failure mode is likely to be corrosion of the wire, 110 terminals,
and jacks, or disintegration of the insulation, which is why I'm
looking at FEP-insulated or silicone grease flooded (direct burial, or
outside plant) cable.
Thanks! |
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glen herrmannsfeldt
Guest
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| Posted:
Thu Jul 21, 2005 8:20 am Post subject:
Re: Harsh Environment Cat5? |
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William wrote:
(snip)
I have never tried it, but the tool should help. Still, it is at
least one extra step.
| Quote: | I've guesstimated the longest run is about 150 feet, maybe I'll dive
back into the Belden catalog for Cat5e-ish DataTwist FEP cable...
The failure mode is likely to be corrosion of the wire, 110 terminals,
and jacks, or disintegration of the insulation, which is why I'm
looking at FEP-insulated or silicone grease flooded (direct burial, or
outside plant) cable.
|
I believe that 110 terminals are supposed to be gas tight, though
maybe that still isn't good enough. Bell was always good at doing
things right so that they wouldn't have to come back and fix them later.
-- glen |
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J. Clarke
Guest
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| Posted:
Thu Jul 21, 2005 4:20 pm Post subject:
Re: Harsh Environment Cat5? |
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glen herrmannsfeldt wrote:
| Quote: | William wrote:
(snip)
There's a tool at
http://www.newark.com/productimages/standard/3765751.jpg for only
$6.82 for splitting the pairs apart, I had assumed that that tool and
the usual punch-block 110 tool would be all I'd need for installing
the cable.
I have never tried it, but the tool should help. Still, it is at
least one extra step.
I've guesstimated the longest run is about 150 feet, maybe I'll dive
back into the Belden catalog for Cat5e-ish DataTwist FEP cable...
The failure mode is likely to be corrosion of the wire, 110 terminals,
and jacks, or disintegration of the insulation, which is why I'm
looking at FEP-insulated or silicone grease flooded (direct burial, or
outside plant) cable.
I believe that 110 terminals are supposed to be gas tight, though
maybe that still isn't good enough. Bell was always good at doing
things right so that they wouldn't have to come back and fix them later.
|
They're gas tight, which is fine for light corrosion, but if you're getting
the kind of heavy stuff that occurs in a marine environment then the
contacts can be attacked from the exposed surfaces. Or the wire may simply
corrode through--used to have a very nice electronic organ that died that
way, and that wasn't a particularly bad environment, just waterfront (not
even beach-front--it was on a tidal estuary about 12 miles inland from the
beach) property in Florida. I finally gave up on replacing the transistors
on the frequency synthesizer boards when their leads corroded through-it
was a regular occurrance. In retrospect I should have potted them in
epoxy, but that was a long time ago when I knew a lot less about certain
things than I do today. Salt spray gets into _everything_. You don't
realize how much it gets into stuff until you move inland.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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James Knott
Guest
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| Posted:
Thu Jul 21, 2005 10:15 pm Post subject:
Re: Harsh Environment Cat5? |
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William P. N. Smith wrote:
| Quote: | This is for inside a single dwelling, so it won't actually be used for
direct burial, but it's a really harsh environment and I'd like it to
last for many decades...
|
You shouldn't expect any cable to last decades. The plastic will harden and
crack over the years, etc. |
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glen herrmannsfeldt
Guest
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| Posted:
Thu Jul 21, 2005 10:15 pm Post subject:
Re: Harsh Environment Cat5? |
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J. Clarke wrote:
(snip)
| Quote: | They're gas tight, which is fine for light corrosion, but if you're getting
the kind of heavy stuff that occurs in a marine environment then the
contacts can be attacked from the exposed surfaces. Or the wire may simply
corrode through--used to have a very nice electronic organ that died that
way, and that wasn't a particularly bad environment, just waterfront (not
even beach-front--it was on a tidal estuary about 12 miles inland from the
beach) property in Florida.
|
(snip)
I think you are right, but the phone companies must have a solution
for this, as they do supply phone lines to such houses. Maybe they
do use grease on the 110 blocks.
-- glen |
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Guest
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| Posted:
Fri Jul 22, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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James Knott <james.knott@rogers.com> wrote:
| Quote: | You shouldn't expect any cable to last decades. The plastic will harden and
crack over the years, etc.
|
That's pretty much why I went with the FEP insulated cable, even
though I don't need the plenum rating for fire. I'm going to pick up
a few tubes of silicone grease for corrosion protection as well. The
CFO said to go with the DataTwist 600e cable, as it's the best stuff
that will function today and have the best chance of future-proofing.
Ask me again in a couple of decades and I'll let you know how it holds
up. 8*)
Thanks for all the input, gang! |
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J. Clarke
Guest
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| Posted:
Fri Jul 22, 2005 12:20 am Post subject:
Re: Harsh Environment Cat5? |
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James Knott wrote:
| Quote: | William P. N. Smith wrote:
This is for inside a single dwelling, so it won't actually be used for
direct burial, but it's a really harsh environment and I'd like it to
last for many decades...
You shouldn't expect any cable to last decades. The plastic will harden
and crack over the years, etc.
|
Only if it was crap to begin with. The electric power cabling in my house
has not hardened or cracked in more than 30 years, and the cable in my
parents house was fine last time I looked at it, at which point it had been
in place for over 50.
The conductor may corrode but without UV exposure the insulation on any
cable that meets any reasonable electrical code will not "harden and crack"
in just a few decades.
If there _is_ UV exposure then you should be using a cable rated for such
use.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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James Knott
Guest
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| Posted:
Fri Jul 22, 2005 7:10 am Post subject:
Re: Harsh Environment Cat5? |
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J. Clarke wrote:
| Quote: | Only if it was crap to begin with. The electric power cabling in my house
has not hardened or cracked in more than 30 years, and the cable in my
parents house was fine last time I looked at it, at which point it had
been in place for over 50.
The conductor may corrode but without UV exposure the insulation on any
cable that meets any reasonable electrical code will not "harden and
crack" in just a few decades.
If there is UV exposure then you should be using a cable rated for such
use.
|
I've seen decades old power wire insulation that's crumbling. The aging of
plastic is a fact, in that the plasticizers that make it flexible,
evaporate with time, even without UV. As an example, take a look at some
food storage containers that are a few years old. They're not as flexible
as they were originally and will eventually crack. |
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J. Clarke
Guest
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| Posted:
Fri Jul 22, 2005 8:20 am Post subject:
Re: Harsh Environment Cat5? |
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James Knott wrote:
| Quote: | J. Clarke wrote:
Only if it was crap to begin with. The electric power cabling in my
house has not hardened or cracked in more than 30 years, and the cable in
my parents house was fine last time I looked at it, at which point it had
been in place for over 50.
The conductor may corrode but without UV exposure the insulation on any
cable that meets any reasonable electrical code will not "harden and
crack" in just a few decades.
If there is UV exposure then you should be using a cable rated for such
use.
I've seen decades old power wire insulation that's crumbling.
|
How old, and what kind of plastic was used? If you go back far enough then
there is no plastic of any kind in the insulation--it's varnished cambric.
That in general _is_ crumbling now. After that rubber was used--it also is
crumbling now. Some of the early plastics may not be holding up either.
But any wire installed in a building in the US that is less than 4 decades
old that is "crumbling" is just plain _crap_ that should never have passed
inspection.
| Quote: | The aging
of plastic is a fact, in that the plasticizers that make it flexible,
evaporate with time, even without UV. As an example, take a look at some
food storage containers that are a few years old.
|
So? It appears to have escaped your notice that there are many kinds of
plastic and the kind from which food storage containers are made is
generally not the kind used to insulate electrical wiring.
| Quote: | They're not as flexible
as they were originally and will eventually crack.
|
This is true for some kinds of plastic but not for all. The hardening
mechanism is usually crosslinking, not "evaporation of plasticizers" and
the reason that UV accelerates aging of plastics is that it increases the
rate of crosslinking. Most modern electrical insulation is already heavily
crosslinked, so that ceases to be an issue.
Now, please explain to me why I can take a piece of wire installed in a
house in 1968, more than three decades ago, and bend it back and forth
until the copper inside the insulation work-hardens and breaks, without any
cracks or any other kind of indication of failure appearing in the
insulation, if such insulation will "crumble" in "decades".
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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J. Clarke
Guest
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| Posted:
Fri Jul 22, 2005 4:20 pm Post subject:
Re: Harsh Environment Cat5? |
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James Knott wrote:
| Quote: | J. Clarke wrote:
Now, please explain to me why I can take a piece of wire installed in a
house in 1968, more than three decades ago, and bend it back and forth
until the copper inside the insulation work-hardens and breaks, without
any cracks or any other kind of indication of failure appearing in the
insulation, if such insulation will "crumble" in "decades".
Compare that insulation with new cable and see if it's as flexible.
|
If it is it's not enough for me to be able to tell the difference. But even
if it is a little stiffer after 30 years, so what? That's a _long_ way
from "crumbling". Now the cheap Rat Shack cable on my antenna rotor _is_ a
bit stiffer than new (I inspected it a while back while I was putting up a
DirecTV dish)--not _much_ stiffer but some. It's been sitting out in the
sun for more than 30 years. Still doesn't crack when flexed.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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