Outside plant - prewire customer demarc preference

Fri Nov 24 17:56:37 UTC 2023

Sorry long, detailed message.

TL;DR - Use 1-inch trade size smurf tube for new North America FTTH 
construction.

North American FTTH may not have standards for the in-building access 
conduit between the demarc point, Minimum Point of Entry (MPOE) in the old 
terminology, and the dwelling's distribution point. But thanks 
to Christopher Hawker for pointing me to other country's national 
broadband deployment guidance.

In the US, we don't even have a consistent word to describe that line on 
the network drawings. That line seems to be an "out of scope" gap between 
the the FCC demarc rules and TIA inside wiring standards.

Other countries with strong FTTH deployments have written a lot of 
rules about that line. Germany has extremely detailed FTTH building 
standards which influenced other European country FTTH standards. Carriers 
in several Middle East and other Commonwealth countries with national 
FTTH deployments have lots of documents for new builders.

Bear with me, because I'm going to translate nominal metric measurements 
and translate country-specific "pre-wire" rules using North American 
terms.  Conduit, tube, pathway generally mean the same thing to me, but 
some people have been annoyed because their country uses different words.

Most FTTH countries specify a nominal 25mm I.D./32mm O.D. (equivalent to 
1-inch US trade size) conduit/duct/pathway between the "dwelling" Distribution Point 
and the NID/demarc entrance point for new construction.  In multi-dwelling 
unit buildings (i.e. apartments) the 25mm/32mm duct is between the 
apartment and a "consolidation point" for a group of apartments or the 
floor.  Mansions (palaces) and other building types specify larger 
access conduit sizes.  Countries vary a little, i.e. UK and Ireland have 
the smallest minimum access duct size (20mm I.D./25 mm O.D.) and some 
Middle Eastern countries have the largest (40mm ID/50 mm OD).  Australia 
is just weird with a Telstra legacy conduit size.

Overall 25mm ID/32mm OD (equivalent 1-inch trade size) is the most common.

The biggest difference between country's FTTH rules are rigid vs. flexible 
conduit and the material specified, i.e. schedule 40 PVC vs. HDPE vs. 
other.

Also very confusing because the metric "Diametre nominel" size for 
pipes/conduit isn't the actual size of the conduits in metric 
measurements. 25mm is really 26.64mm inside diameter. Likewise the 
American National Pipe Standard isn't the actual measurement either. 
American 1-inch trade size is 1.029" inside diameter. The convention 
metric countries uses for 32mm outside diameter is really 33.40 mm.

Confused yet?  Google translate does not help with construction codes.

The good news for North America construction, a 1-inch trade size 
HDPE/Schedule 40 PVC or smurf tube/duct/conduit/pathway requires drilling 
a 1-3/8 inch hole through framing studs.  A 1-3/8 hole is just smaller 
than the maximum sized hole size allowed in a standard 2x4 framing stud 
(which isn't actually 2-inches by 4-inches) by North American building 
codes.  So the builder does not need to charge extra to 'double' the 
framing studs for 'structural integrity' according to the building code.

Builder's scare quotes are intentional.

Insert NSFW construction joke here :-)

Mine (and my friend who will own the the new house) assumption is the 
builder's proposed $1,000 charge is really a "stop listening to your 
crazy friend, and let me build your house" charge.