FOA Guide


Fiber To The Home Installation

   There is probably no way to generalize on the installation process for FTTx since every system is unique and, in some cases, every subscriber is different. Rather than telling you how to install FTTx here, we will try to illustrate some of the ways that others have installed their systems and offer advice on how to install systems most efficiently.

    Instead of duplicating information elsewhere in the FOA Guide, which has a long section on fiber optic construction and outside plant installation, we will focus on FTTH specific topics and link you to some FOA online materials that cover relevant topics. We also recommend you read the FOA Guide pages on FTTH and especially the page on FTTH Network Design before starting on this page.

 
Most FTTH networks are based on a PON network. The drawing below defines the network: a "feeder" cable extends from the OLT (optical line terminal) in the CO (central office) to a FDH (fiber distribution hub) where the PON (passive optical network) splitter is housed. It then connects to "distribution" cables that go out toward the subscriber location where "drop" cables will be used to connect the final link to the ONT (optical network terminal).

FTTH PON jargon



    The installation of the cable plant to the point where the drop goes to the subscriber is basically standard outside plant construction and outside plant installation which you should be familiar with for FTTH installation. Installation of feeder and distribution cables generally follows standard OSP practice, but the drop cables are unique to FTTH. The cables are often different from normal OSP cables because they have fewer fibers ( 1 or 2 generally) and are more often factory terminated for plug-and-play at the subscriber interface for single family homes. MDUs (multi-dwelling units) will generally follow fiber to the building conventions with patch panels inside the building.

   
Preterminated or prefab cables became popular when FTTH service providers realized that they could eliminate the need for experienced splicers at the subscriber installation. Instead the home installation tech could simply plug in the drop cable, hook up the ONT and connect customer devices. The would only get involved with running cables inside the house if necessary.
 
    Prefab cables can be factory terminated on one end or both. If the cable plant used these drop boxes for prefab cables (below), the drop cables will be terminated on both ends and excess cable will be stored in service loops. Installation of the cable is simply attaching aerial cables, pulling cables in conduit or using simple trenching techniques to bury the cable in the subscribers lawn. Keeping buried cables close to sidewalks and driveways minimizes the possibility of them being dug up. And like all underground construction, the installer needs to be aware of any underground utilities in the subscriber's yard, especially sprinkler systems or invisible animal fences which are often poorly documented.

FTTH prefab
Closeup of the six-port drop.

    Some special FTTH fiber closures for drop cables require terminating the drop cable to connect it to the box. Patching with connectors in a re-enterable closure has become a popular option to splicing as it allows adding new drops when needed. These closures generally use splice-on connectors, either mechanical or fusion splices, on the bare end of the drop cable. This minimizes the problem of storing excess lengths of cable in service loops. The drop cable can be installed at the subscriber end to the closure then terminated, eliminating most of the excess cable storage.

FTTH Drop Cable Closure

  This closure has entries for distribution cables, including one coming in and one continuing on to another closure for daisy-chained cables.  There are multiple outputs for drop cables which are terminated in connectors.
Some closures like this one have provision for splicing on pigtails to terminate the distribution cables while others are designed for direct termination using splice-on connectors using either fusion or mechanical splicing. 

    If the design calls for termination at the customer premises, these same splice-on connectors are generally used to get reliable terminations quickly. The mechanical spice on connectors require special tool kits and some practice to get good yield. The fusion splice on connectors require a fusion splicer but several are available at costs not much greater than the took kits for the mechanical splice types and require less skill to get good yield.

    We're focusing on the fiber part of the installation but the FTTH home tech will have to know how to connect fiber, set up the ONT and connect all the subscriber's devices. That is a very different skill from fiber optic installation.

Summary
  Like most fiber optic networks, every FTTx installation is unique. It must be designed for the location it is to serve and choices on components and installation methods should be optimized for the system. Installation methods may include every type of OSP installation. Suppliers familiar with FTTx can advise customers on what other systems have done to make installations simpler, easier and inexpensive. Most systems prefer to use as many factory-made components as possible as they are generally less expensive than doing the same work in the field. New installation methods should be considered as well to reduce costs.

     Contractors need to be well trained (and preferably FOA Certified) and experienced in the tasks they will be doing. Good installers will make the installation easier, faster and cheaper because they will make fewer mistakes. Because of the cost pressure on FTTH service providers, contractors are often chosen by price and then they often subcontract to cheaper, lesser skilled contractors. There have been instances where poorly trained installers, even landscape contractors, have been hired to do installations and have cut other fiber optic cables, punctured water mains flooding neighborhoods or even breaking gas mains causing explosions. Choosing wisely is important.



Technical Information on FTTX  From The FOA Online Guide
FTTH Introduction  
FTTH Architectures
FTTH in MDUs (Multiple Dwelling Units)  
FTTH PON Standards, Specifications and Protocols  
FTTH Design    
FTTH Installation 
FTTH Customer Premises Installation  
FTTH Network Testing  
FTTH Case Studies: Do-It-Yourself FTTH  

Training & Certification
Fiber U Online FTTx Self Study Program (free)

FOA Certification Overview
FOA FTTx Certification Requirements
FOA-Approved Training Programs


 Table of Contents: The FOA Reference Guide To Fiber Optics





 


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