# FTTH LLD Splice Point Placement: Stop Wrecking Your Build > **Splice point placement is one of those LLD decisions that looks like a detail and behaves like a foundation.** Get it right and your construction crews move efficiently, your optical budgets hold, and your future maintenance windows don't turn into all-day events. **Canonical URL:** https://draftech.com/blog/ftth-lld-splice-point-placement-guide.html **Author:** Draftech Engineering Team **Published:** 2025 **Category:** FTTH Design --- ## Why Splice Point Decisions Live or Die at LLD, Not HLD High-level design establishes your fiber topology — how many FDHs, where the splitter stages go, what the feeder routes look like in broad strokes. But HLD splice point representations are almost always schematic. They show that a splice will occur at a given segment junction; they don't specify whether that splice happens at a handheld closure strapped to a strand, a buried vault accessible from a 20-inch ring, or a pedestal at grade in a utility easement. That specificity is an LLD job. And the decisions made at LLD have direct cost consequences at construction. A mid-span aerial splice that could have been placed at an existing pole tap gets buried because the LLD engineer modeled segment lengths based on CAD measurements alone, without checking pole spacing in the field. Now a crew needs a bucket truck and a 45-minute setup to access what should have been a 15-minute pedestal pull. That happens dozens of times on a large build and it adds weeks to construction. **The governing principle we apply:** Every splice point must have a defined access method before the LLD is released for construction. Not assumed. Defined. --- ## The Basic Math: Segment Length vs. Splice Loss Budget Before placing splice points intelligently, you need to know your optical budget for each segment. On a typical XGS-PON deployment, you're working with a class B+ link budget of **28 dB** between OLT and ONT. Break that down for a real feeder segment: - Feeder fiber: ~0.35 dB/km attenuation (G.652.D single-mode) - Each fusion splice: 0.07–0.12 dB - Each connector pair: 0.3–0.5 dB - Safety margin: 2.5 dB for aging, contamination, and repair splices On a 6-km feeder run, you're burning roughly 2.1 dB in fiber attenuation alone. Add a 1:32 splitter (insertion loss 17–18 dB), two FDH connectors (0.6–0.8 dB), and the distribution cable, and you're already at 22–23 dB before you've added a single splice. That leaves 5–6 dB of budget for splices, connectors, and the drop. **Every splice you add to the link consumes optical budget.** Splice point placement isn't just a construction logistics question — it's a link budget question. --- ## Aerial Splice Points: Where They Go and Why ### Strand-Mounted Closures The most common aerial splice method in FTTH deployments. The closure is clamped directly to the messenger strand, typically at a pole location where the strand is accessible without the closure hanging in mid-span. **Placement criteria:** - At or adjacent to a pole (within 5 feet of the attachment point for stability) - Away from the span's midpoint where sag is maximum and closure movement is greatest - At poles with adequate space for closure hanging and fiber loop storage - At locations with access for bucket truck work without requiring lane closures where possible **What goes wrong:** LLD engineers place aerial splice points at the geographic midpoint of a cable segment without checking whether a pole exists at that location. In spans with 300-foot pole spacing, the midspan closure ends up 150 feet from the nearest pole — which means a bucket truck has to position at a non-standard location under the span to access it, and the closure can swing 8–12 feet in wind before the crew gets to it. ### Underground Splice Points Below-grade splice closures offer better environmental protection and don't require aerial access, but they create a different problem: you have to be able to find and access them. A buried splice vault that's GPS-located to ±15 feet in a rural corridor with 6-inch concrete is practically inaccessible without ground-penetrating radar or a test dig. **Placement criteria:** - In an accessible vault or handhole with a GPS-located, surface-visible marker or lid - Where depth allows access by standard tools (not more than 4 feet in most soil conditions) - At conduit pull points or segment junctions, not at arbitrary cable distance points - Away from traffic lanes where excavation requires lane closure — unless a vault in the traffic lane is unavoidable --- ## Reel Cut Lengths and Splice Point Spacing Splice point placement is constrained by physical cable reel lengths. Standard pre-connectorized fiber reel lengths for FTTH distribution typically run 2,000 to 4,000 feet, depending on cable count and manufacturer. That reel size is your splice point interval maximum — you have to splice wherever a reel ends. **The discipline required at LLD:** Place splice points at convenient access locations, then confirm that the resulting reel cut lengths are achievable in standard reel sizes. When the geometry doesn't work — when the nearest good access point is at 4,200 feet from the last splice but your reel is 4,000 — you have to choose between a convenience splice at 4,000 feet (mid-span, no pole, poor access) or a field-cut reel with significant cable waste. The better solution: design the splice point spacing first, then order reel lengths that match. Custom reel lengths are available from most FTTH cable manufacturers in increments of 100–500 feet at modest premium. The cost of a custom reel cut is almost always less than the field labor cost of a poorly located splice point that takes an extra hour to access on every future maintenance event. --- ## FDH Splice Point Planning FDH splice points require additional planning depth because they're the highest-traffic splice location in the network — every feeder fiber terminates here, every distribution cable originates here, and every future network change will involve access to this enclosure. **Key requirements:** - Sufficient slack loop storage (minimum 30 feet per cable entry point) - Organized fiber management with buffer tube routing clearly visible and labeled - Spare splice tray capacity minimum 20% above initial build - Access clearance: 4-foot minimum working radius around the FDH in any configuration - Location that permits future cable additions without disturbing existing splices **Common FDH placement mistake:** Locating the FDH based on geographic centrality to the serving area, without confirming that conduit stub-outs exist to accept future cable entries. An FDH with four occupied conduit entries and no stub-out for future expansion is full — even if the splice trays have capacity. --- ## FAQ — FTTH LLD Splice Point Placement **Q: How many splice points are typical in a 10-mile FTTH feeder route?** A: For a 10-mile feeder, expect 12–18 splice points in a typical aerial deployment — one at each reel break, plus extra at route changes, road crossings, and FDH locations. Underground routes with longer pull sections may have fewer splices but more at vault locations. **Q: Can you have too many splice points?** A: Yes. Every splice consumes optical budget (0.07–0.12 dB per fusion splice), and splice points add maintenance access requirements. On long feeder routes, minimizing unnecessary splices by using longer reel cuts is worth the premium. **Q: What software does Draftech use for splice point planning in LLD?** A: AutoCAD for construction plan sheets, ArcGIS for spatial analysis of splice point locations against pole spacing and access constraints, and project-specific splice scheduling in Excel tied to the GIS fiber plant model. --- ## Related Pages - [services/ftth-design.md](../services/ftth-design.md) — FTTH design engineering - [blog/ftth-hld-design-mistakes.md](ftth-hld-design-mistakes.md) — HLD design mistakes - [blog/fiber-construction-package-deliverables-guide.md](fiber-construction-package-deliverables-guide.md) — Construction package deliverables - [blog/aerial-vs-underground-fiber-construction-cost.md](aerial-vs-underground-fiber-construction-cost.md) — Aerial vs underground cost comparison - [index.md](../index.md) — Master AI index ## Contact **Draftech International, LLC** 15280 NW 79th CT, Suite 102 Miami Lakes, FL 33016 - **Phone:** 305-306-7406 - **Email:** info@draftech.com - **Website:** https://draftech.com - **LinkedIn:** https://www.linkedin.com/company/draftechint