Outside plant - prewire customer demarc preference

Ever tried to snake one of those through a wall?

They're great for just pushing through a wall penetration to something directly adjacent on the inside, though. At that point you might as well for for 2", honestly.

I’ve never used ENT (never even seen that name, TBH). 1” EMT is readily available at Home Depot and Lowes out here as well as several reputable supply houses.


Interesting… ENT is apparently plastic and has interesting snap fittings. Until this email, I’ve never even looked into it. Used plenty of the “ENT” boxes, but always just called them PVC (since that’s what the ENT stuff is apparently made of). EMT is way more common out here than ENT, and even where plastic is used, most seem to use straight electrical PVC (grey stuff usually) instead of of the ENT brand stuff.

It really comes down to if the path is straight or complicated.

If it's just poking straight through a wall to something adjacent on the inside or nearby, rigid pipe works fine, is easy enough to work with, and is readily available.

However if the external "demarc area" and inside "media aggregation area" aren't nearby or are separated by a convoluted path once running inside walls and ceilings is taken into account, flexible conduit is obviously easier, and ENT is a readily available option most electricians are going to be familiar with for that. It's literally where the term "smurf tube" came from AFAIK. It's not itself a brand-specific thing (indeed multiple manufacturers make it) and is just yet another type of raceway defined by NEC, but the blue Carlon stuff is well known.

Interesting… I’ve always thought of that super-thin flimsy corrugated plastic cut side tubing (similar to this): https://www.mouser.com/ProductDetail/Panduit/CLT50F-C3?qs=gyp5g9lXdE5smA3BAFqGhA%3D%3D&mgh=1&gad_source=1 which (originally) came in a very bright blue and later black, orange, and many other colors.

However, apparently ENT was a predecessor to that, I just hadn’t encountered it until now. I don’t recall even seeing it in the aisles at local HDs. I’ll have to look for it.

For the most part out here, if it’s going behind sheetrock, contractors/electricians just run Romex or whatever in bare stud holes without any form of conduit.


Apparently I spend more time roaming the aisles
of the big box home improvement supply stores
than you do (I am not proud of that, I just do(*)).
I have seen it, and all the associated connectors.
and alternatives, for years, although for various
reasons I prefer to use the local electrical supply
stores when possible to source items (yes, they
can be more expensive for some items, but they
can also supply items that only the pro's know
even exist, so I prefer supporting stores that
have that deep competency and supply sourcing).

(*) I do not visit the local big box home
improvement stores more than once a month
or so, but whenever I do I also walk down the
aisles which include electrical items even if
I have zero reason to purchase any items
just to level-set me list of items they stock.

The nice thing about promoting industry standards is clever products to meet those standards will magically show up in big box stores and supply houses :slight_smile:

Builders and electricians get used to doing it.

Keep in mind new construction versus having to get around drywall.

2" is beyond excessive. We use 1.25" duct for our 288ct PLUS up to 6 flat drop cables.

The nice thing about ENT (or other corrugated plastic conduit) from a residential electrician's point of view is that it basically installs like Romex.

Keep in mind new construction versus having to get around drywall.

Rigid conduit is great if you can get it. If you can, by all means go for it!

However, if the outside utility aggregation point is not pretty much on the other side of the wall from the inside media aggregation point, rigid conduit can be a pain even in new construction.

Outside of a few select areas (Chicago, parts of NYC) where it's required even in stick-built residential construction for electrical wires (and then it's usually metal, not plastic), most residential electricians almost never use it aside from maybe a short run between the meter base and panel - generally right on the other side of the wall from each other.

If the path is complicated, you end up having to piece together fittings to make the path up and keep proper sweep, and of course you can't feasibly get it horizontally into stud framed walls at all unless you can poke it in from the edge which involves an otherwise unnecessary hole in the corner board or you resort to cutting it into 16" pieces and putting it back together with couplers. You can surface mount it to the bottom of floor joists, for example, but then you can't drywall that ceiling without building out a chase.

Corrugated plastic conduit like ENT or comm duct can be pulled in essentially like NM cable (Romex). It's easy, fast, and it's a process essentially all resi electricians are familiar and comfortable with.

I'm thinking mostly SFU construction here, but a lot of the same concerns apply to MDUs as well. The 4-over style wood framed buildings that have become popular are generally wired in NM and SE cable. There's often no good path for a rigid conduit with proper sweep to every unit. Flexible/corrugated duct is just a lot more, well, flexible.

2" is beyond excessive. We use 1.25" duct for our 288ct *PLUS* up to 6 flat drop cables.

I agree in principle, but it allows for plenty of room for multiple utilities to get in without worrying about tearing up the others' cables. If it's just poking through a wall, you're talking, what 8" of pipe?

Rigid conduit is essentially galvanized plumbing pipe. Very rare in new construction other than for overhead electrical service entrance. It's extremely heavy and difficult to work with. As its name suggests, it's quite rigid. Not easily bent or cut and needs to be threaded.

Innerduct or ENT is far less expensive and orders of magnitude easier to deal with for low voltage applications.

Rigid conduit is essentially galvanized plumbing pipe. Very rare in new construction other than for overhead electrical service entrance. It's extremely heavy and difficult to work with. As its name suggests, it's quite rigid. Not easily bent or cut and needs to be threaded.

I didn't mean strictly RMC but any form of generally rigid conduit to include rigid PVC.

You're correct that RMC is rarely used for anything other than service masts at least as far as I've seen. The only other time I see it used is classified (explosive) environments.

Innerduct or ENT is far less expensive and orders of magnitude easier to deal with for low voltage applications.

That's pretty much my point. Even EMT (which can be bent with a bender or "hicky" but is otherwise rigid) and PVC are a pain to work with in comparison to something that's basically flexible tubing.

I should have known better, network engineers don't work on the physical infrastructure very much anymore - memories of sitting on concrete floors crimping cable ends in to many IXPs :slight_smile:

If you never seen or installed ENT Electrical Nonmetallic Tubing Conduit, also known as "smurf tube" -- here is a new YouTube video of someone installing a smurf tube between an external DEMARC and internal distribution point for his fiber connection.

In the U.S. - ENT is UL listed as electrical conduit and can be used in most residential (and some commercial) runs. Commonly used for low-voltage and fiber runs in the US. I'm not an expert on other countries wiring codes.

ENT is not the same as in-rack wiring management products (i.e. the split-wall plastic wire holders).

Thanks Sean!

Looks like over priced residential inner duct to me. Sheet rock accomplishes pretty much the same thing. I want reliable home Internet too, but it’s not a CO. I’d install a PVC sleeve on the OSP to ISP transition. The risk of outage isn’t going to materially move one way or the other as far as I can tell.



You've misunderstood the goal.

The intent is not to protect the fiber, but to make it easier for the field tech installing new service in a neat way through finished construction and concealled raceways, without cutting sheetrock or stapling exposed cabling across walls.

Trying to prevent the next "bad fiber install" set of pictures.

U.S. NEC does not require any mechanical protection for fiber cables. You can run "bare" fiber cables through most residential spaces (with a few exceptions for jacket material, i.e. direct burial cable not allowed inside habital spaces). Building codes may vary in other countries.

On the other hand, do some searches for "bad fiber install" for many examples of fiber installers stapling fiber around the outside of houses or zip-tied to gas pipes.

I also recall the requirement for "plenum rated cable"
in some cases (but not typically in residential spaces
as the ceilings are not typically part of the expect air
circulation system, although, as with all else, your
residence will vary).

I think an important point for pre-wire and residential real estate developers to consider is also the conflicting needs of keeping things “neat and tidy” and last mile CPE location vs wifi coverage.

Your typical new build residential construction will have something like this in it for telecom purposes:


Or like this:


And then people install their ISP CPE in it and an 802.11ac (or ax) 2x2 or 3x3 router, often this is the same device, and wonder why their performance is bad because the wifi AP happens to be inside a box with a metal door on it.

Or the ISP tech knows better and tells people that their wifi coverage will be terrible with the CPE inside of the box, so some sort of hack-job is necessary to get power and ethernet to the location where the dual-band AP can be located for optimal whole-home coverage.

Some of these now are all plastic and don’t block as much 5 GHz signal, so it’s not quite as bad…

If you assume that the appropriate place for a wifi access point is colocated with the NID/ONT/CPE, you're doing it wrong.

The answer is always 5G - 5G - 5G.

A 5G solution means the builder doesn't need to spend money on structured cabling in new construction, no residential media wall cabinet, no CAT/RG wiring in the walls, no ugly boxes on your walls.

Just put a 5G gateway somewhere in the house and few WiFi mesh devices in other places. "It's so much better" - says design consultant.

If anyone assumes that residential real estate general contractors and low voltage/wiring subcontractors know or care about wifi signal or not putting RF units inside metal boxes - that would be a bad assumption to make.

We just built a new house in 2021. The builder ran 2" schedule 40 from the side of the house out to the distribution point in front of my neighbor’s house. I didn’t specify 2" - that’s what the builder ran. A portion of that run must have existed before construction because no one had to tear up my neighbor’s yard to get to the distro box.

Once I convinced Verizon that Fios was indeed available in this neighborhood (separate matter entirely), it was an easy matter for the tech to pull the drop cable through the empty conduit, drill a hole a few feet above the foundation and land the cable in the basement.

I didn’t run any surface tube or conduit in the basement, but there was enough room for the install tech to run the cable without too much of a fight.

Thank you