I can't speak for US standards, however, in Australia on the National Broadband Network the standard for lead-in conduit is P20 conduit (23mm inner diameter with 26.6mm to 26.8mm outer diameter). I imagine in the US it may be something similar.

Page 17 of https://www.nbnco.com.au/content/dam/nbn/documents/developers/newdevs/NBN-DES-STD-0011-Residential-Preparation-and-Installation-Single-Dwelling-Units-and-Multi-Dwelling-Units-13.0.pdf.coredownload.pdf.

Regards,
Christopher Hawker

From: NANOG <nanog-bounces+chris=thesysadmin.au@nanog.org> on behalf of Sean Donelan <sean@donelan.com>
Sent: Thursday, November 23, 2023 4:35 AM
To: nanog@nanog.org <nanog@nanog.org>
Subject: Re: Outside plant - prewire customer demarc preference
 

For *only* $1,000, the builder is willing to pre-install a smurf tube from
the demarc to the central distribution point.  But such a deal for 5G....

Since most fiber installs seem to use pre-connectorized cable, without
affecting building structure integrity (i.e. 2-inch is too big according
to builder), how small is too small?  Trade size 1/2-inch, 3/4-inch,
1-inch?

Does the FTTH industry have any published standards?


This is why I don't help friends troubleshoot PC printer problems :-)