Handhole and Vault: Definition and Function in Fiber Networks
A handhole is a small underground fiber access point. A vault is the larger, walk-in version. Get sizes, tier ratings, and when each is used.
A handhole is a small underground enclosure, usually precast or polymer concrete, that gives crews access to buried fiber cable for splicing, testing, and maintenance without full excavation. A vault is a larger underground enclosure, often walk-in or crawl-in, used for high fiber counts, large splice closures, or terminal equipment.
Handhole vs. Vault: What Sets Them Apart
Size and access are the main differences. A handhole is small enough to lift by hand or with a hook, usually rated for foot traffic or light vehicle loads, and sits at shallow depth over a straight run or minor splice point. A vault is bigger, sometimes large enough for a technician to stand or crawl inside, and holds higher fiber counts, larger splice trays, or active equipment like optical terminals. Vaults also carry heavier traffic ratings for placement in roadways, driveways, or parking areas. Both protect cable and splices from soil load, moisture, and physical damage while keeping the network accessible without repeated trenching.
Sizing and Load Ratings
Handholes and vaults are specified by tier rating and physical dimensions, not by guesswork. ANSI/SCTE 77 defines tiers from Tier 5 (light duty, off-roadway) up through Tier 22 (heavy roadway and highway loading). A typical handhole runs from about 13x24 inches to 30x48 inches, while vaults commonly start at 4x6 feet and scale up to 6x10 feet or larger for major splice or distribution points. Material is usually polymer concrete or precast concrete for strength and corrosion resistance, with covers rated to match the surrounding traffic load, whether that's a sidewalk, a shoulder, or a live traffic lane.
Where Handholes and Vaults Fit in an OSP Build
Engineering design drives the choice, not preference. Handholes go in at regular intervals along a route for pulling, mid-span access, and small splice points, keeping placement spacing within cable pull-tension limits. Vaults go in at network hubs, such as central office entries, cabinet locations, or points with dense splice counts and multiple cable entries, where crews need room to work and equipment needs housing. Getting placement, depth, and tier rating wrong means re-digging later, so both should be called out on the underground construction plan set before crews break ground, matched to soil conditions, right-of-way rules, and expected traffic loading at each location.
Handhole and Vault, answered
What is Handhole and Vault?
A handhole is a small underground enclosure, usually precast or polymer concrete, that gives crews access to buried fiber cable for splicing, testing, and maintenance without full excavation. A vault is a larger underground enclosure, often walk-in or crawl-in, used for high fiber counts, large splice closures, or terminal equipment.
What is the difference between a handhole and a manhole?
A handhole is a small, often hand-liftable enclosure for cable access and light splicing. A manhole is a larger, walk-down structure sized for a technician to enter and work standing up, typically used for higher-count cable runs, major splice points, or conduit congestion in dense underground networks.
What size handhole do I need for a fiber project?
Size depends on cable count, splice tray capacity, and expected traffic load. Small handholes (around 13x24 inches) suit single-conduit residential runs. Larger sizes, up to 30x48 inches or more, handle multi-conduit routes, higher fiber counts, or distribution splice points. An engineering plan set should specify exact dimensions and tier rating per location.
Are handholes and vaults traffic rated?
Yes. Both are manufactured and installed to specific load tiers under ANSI/SCTE 77, ranging from light-duty off-roadway ratings to heavy highway ratings. The correct tier depends on where the structure sits: sidewalk, shoulder, driveway, or live traffic lane, and gets specified during OSP engineering, not chosen in the field.