Re: CAT5e cable

On 4/20/2025 9:16 PM, Jeff Liebermann wrote:

On Sun, 20 Apr 2025 03:57:28 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:
 

I've been just picking up whatever (riser) cable is conveniently available,
in the usual 1000 ft boxes.  No real focus on manufacturer, etc.

 What type of outer jacket did you buy?  CL, CM, CMG, CMR, CMP, CMX,
CMX2, CMX3, etc?

CMR

Are you dealing with any kind of fire or smoke related requirements?
Some jackets trade slow burning, so that a fire doesn't spread as
quickly, for generating toxic smoke.  If you're installing cable in a
vertical shaft that is full of potentially combustible insulation, you
want something that smolders and not burn.  However, if the cable is
being run through an air shaft (plenum), you want something that
doesn't generate much toxic smoke.

Yeah, this is just riser cable.  I don't think it is allowed
to run wire through a plenum in a residence, here.

"Understanding Cable Jacket Ratings: CL, CM, CMR and CMP"
<https://www.cmple.com/learn/understanding-cable-jacket-ratings-cl-cm-cmr-and-cmp>
 Incidentally, for an interesting outdoor experiment, cut about 1 meter
of each type of cable, hold the wire vertically, and use a butane or
propane gas lighter to ignite the lower end of the cable.  Note which
types of cables smolder or burst into flames, and the amount of smoke
each type produces.  Also, wear heavy gloves, use eye protection, and
have a bucket of water nearby.

And, don't let it "drip" on you!

But, had to run some drops in EMT recently and noticed a marked difference
it the overall durability of the different cables that were being fed.
One seemed "flimsier" than the other -- no doubt related to the jacket
composition.

 Yep.  I've also seen this.  The cable was very brittle and could be
bent only a few times before it cracked.  However, it has been too
long and I can't recall what type of cable was being used.  It was in
a hospital so it probably was CMR flame retardant insulation.

The cable hasn't failed.  But, I noticed that it was just "flimsier"
than the other cables I had run in the same conduit.

Since you're complaining about the lack of "durability" and running
cable through EMT conduit, you might want to calculate the minimum
bend radius:
<https://www.truecable.com/blogs/cable-academy/minimum-bend-radius>

Yes.  Also conduit fill capacity.

I notice the cable from the (outdoor) modem has an even more duable
jacket.  But, attribute this to it being "outdoor" cable (none of the
stuff I've purchased has been thusly labeled)

 Outdoor cable usually mean UV resistant.  It can also be direct burial
cable where the space between the wires and outer jacket are filled
with silicon slime.  It does a good job of keeping the water out of
the cable, but does make a mess.  If used as a cable "drop" between
the pole and a building, it should have a messenger wire to keep the
Ethernet cable from stretching.  Lots of interpretations for "outdoor
cable".

It tends to be thicker (OD) so, unless some good reason to use it,
not the sort of thing I want in EMT as it reduces the number of
conductors that can be accommodated.

Any tips on what to look for in a *description* to select for the "nicer"?
cable?  (I could probably look at the markings on the jackets to identify
the different brands)

 Ummm... yes, it would be nice if you would disclose the maker and the
numbers on printed on the cable.

There are at least 7 different boxes in use.  I'd have to thumb through all
of the wires at the distribution panel to tabulate their various part
numbers.
The issue, here, was if there was some other aspect that I hadn't been
aware of when selecting the cables.  Of course, the boxes are pretty
skimpy on describing the cables:  CMR, 4pr 24AWG, copper, grey, etc.
(I've learned there are different interpretations for "grey" but that
isn't important to me)

"Ethernet Cable Identification for Beginners: Reading Print Legends"
<https://www.truecable.com/blogs/cable-academy/ethernet-cable-id-for-beginners#>
 Incidentally, watch out for CCA Ethernet cable.  CCA means copper clad
aluminum.  CCA is cheaper than 100% copper, but everything else about
it is horrible:
"Why You Should Stay Away from CCA Cables?"
<https://www.systoncable.com/stay-away-from-cca-cables/>

Yes.  All is well except for this "issue" -- which is tolerable just
requires extra care when feeding through EMT that isn't composed of
just straight runs.