Author: May Lee : may@unigreatfiber.com
Fiber handholes (also known as fiber hand holes, handhole fiber units, fiber handholes, fiber optic handholes, or telecom handholes) are a critical aspect of fiber optic networks. These are shallow underground chambers that provide access to telecom cables and components so that installation, maintenance, and splicing can be accomplished more easily.
The selection of the handhole sizes is not just a capricious process. The size depends on how many cores are contained in the fiber optic cables as well as the future expansion plans and the requirements of installation and operation.
To clarify the basic purpose of a fibre hand hole, it is much more than an access point to underground ducts or innerducts during installation of cable. It is also a place to store any slack cable and splice closures. An important restriction on the size is the minimum bend radius of the cable both for the case of the fibre, which when exceeded will cause breakage of the fibres which in turn will interfere with the signal. Hence, the selection of handhole sizes can be an important factor in the reliability of the network.
Industry Best Practices for Matching Handhole Sizes to Fiber Core Counts
Industry best practices for matching handhole sizes to the number of cores in a fiber core tell a very clear and specific story.
Large backbone cabling, for use in data centers, campus deployments, or interbuilding cabling, with 288 or more cores, will have fiber handhole sizes such as 30" x 48" x 36", 24" x 36" x 36", etc., for sizing. The reason for this is simply that there has to be room enough to house both the large cables plus the splice closures for the necessary signal continuity.
For 144-core cables, more common to medium-sized networks (hospital or office building intra-connecting), handhole sizes of a smaller, but still sensible, dimension such as 17" x 30" x 24", or 24" x 36" x 24" would do. The spacing of the cable slack will be less demanding, but there is still some storage required, and an adequate provision must be made for the installation tools employed.
For networks of a much smaller nature, based on 12, 24 or 48 cores, the need for intermediate handhole sizes is often sufficient. Handhole sizes such as 17" x 30" x 24", or 12" x 18" x 18" will adequately see to the needs of these devices, but here there is some very definite stipulation: if the intermediate handhole should possibly be utilized for future splicing or as a point of assistance in installation devices, then the size will be the same as the splice handhole, for the very good reason that in making this choice, there remains an attitude towards future regrettable retrofits.
Future Expansion and the Importance of Choosing Larger Handhole Sizes
Future expansion is another critical consideration that can't be overlooked. Even if low-core cables are used in the network today, if larger handhole sizes (for example, an increase from 12 x 18 x 18 inches to 17 x 30 x 24 inches) are used, much time and money can be saved later.
There is no need to excavate and replace smaller handholes when additional cables or splice cases are added. Also, best results can be obtained from the time of construction, if innerducts should be placed in such a way that their entrance near the corners or points of the handhole is permitted. A lot of useful room is thereby given for coiling excess slack cable in the handhole, which adds materially to the functionality of handhole sizes in design.
Compliance and Standards for Handhole in Fiber Networks
Last but not least, all of the various local and state regulations, as well as those of the federal government, should be taken into account. It is the business of the outside plant engineers to see that all local requirements for loading of vehicles, i.e. whether the handhole construction can withstand the normal vehicle traffic on the roadway, as well as the state and federal standards on materials used, should be incorporated in the region where the handholes are to be selected.
Such important rules as these if passed over may result in a serious delay for the whole community or injuries to individuals.
Conclusion: Planning the Right Handhole Sizes for a Reliable Fiber Network
To sum up, then, sizing of fiber handhole sizes for the various core count cables requires a large amount of technical accuracy as well as looking far into the future. For example, choosing handhole sizes according to the number of core cables in use today, taking into account the minimum bend radius, planning for future expansion, and conforming to the specifications laid out by the governing boards, whether they be local, state, or federal, will result in a dependable and adequately constructed fiber optic network that is long lasting, efficient, and ready to face the future.
Whether it concerns a small office network or a large campus backbone, handholes play a critical role in building a reliable and lasting fiber optic system.
