FTTH Box Selection Guide: What Type of Fiber Termination Box Do You Need?

Meta Description: FTTH box types explained — wall-mounted, pole-mounted, distribution box, termination box, optical junction box. Learn how to choose the right FTTH enclosure for MDU, OSP, and indoor installations in 2026.

Article overview

In an FTTH (Fiber to the Home) network, the fiber cable runs from the central office through outside plant, enters a building, and terminates at the subscriber's wall outlet. Every step along that path needs an enclosure — somewhere to splice fibers, split the signal, and protect the connections from dust, moisture, and tampering.

This guide explains the common types of FTTH boxes, where each one is used, and what specifications to look for when specifying enclosures for your network.

Table of contents

1. What is an FTTH box?

2. Common FTTH box types

3. Wall-mounted vs pole-mounted vs pedestal

4. Splitter integration: cassette vs plug-in

5. Splice capacity and fiber management

6. Materials, ingress protection, and mounting

7. What to specify on a bill of materials

8. Frequently asked questions

What is an FTTH box?

An FTTH box (also called a fiber termination box, optical distribution box, or FTTH enclosure) is a weatherproof housing that encloses:

• Fiber splice trays (fusion splices or mechanical splices)
• PLC splitters (often 1:8, 1:16, or 1:32)
• Adapter panels (SC/LC/FC adapters)
• Pigtails and patch cords

Its job is to:

• Protect fiber connections from water, dust, and UV exposure.
• Organize slack fiber with proper bend radius.
• Provide a lockable access point for technicians.
• Distribute one incoming fiber into multiple subscriber outputs.

GYAPT manufactures a full range of FTTH terminal boxes for OEM/ODM operators.

Common FTTH box types

2.1 FTTH Distribution Box (ODB / FDT)

The outdoor distribution box sits on a pole, wall, or pedestal near a group of buildings. It houses a PLC splitter (typically 1:8 to 1:32) and distributes signals to individual drop cables. This is the most common enclosure in a PON outside plant.

Typical specs: 1 input cable, 8/16/24/32 output ports, IP55/IP65, PC/ABS or stainless steel.

2.2 Optical Network Terminal (ONT) Box / Mini FTTH Box

A small indoor enclosure mounted on the wall inside a subscriber unit or MDU corridor. It terminates the drop cable, holds a splice tray, and provides an SC/LC adapter for the subscriber's ONT. Often called a faceplate or optical outlet box.

Typical specs: 1 input, 1–4 output ports, wall-mounted, IP40.

2.3 Splice Closure / Joint Box

Used for aerial, buried, or duct cable joints. Not a distribution box — this is where two fiber cables are spliced together in the outside plant. Round, inline, or dome-shaped.

Typical specs: up to 288 splices, IP68, heat-shrink or mechanical seal.

2.4 Optical Distribution Frame (ODF) / Rack Mount

Indoor rack-mounted enclosure in the central office or cabinet. Holds high-density splitter cassettes, patch panels, and fiber management trays.

Typical specs: 1U/2U rack mount, LC/SC adapters, splitter cassette slots.

2.5 FTTH Cabinet (Street Cabinet)

A larger roadside enclosure that houses splitters, ODF modules, and sometimes battery backup. Serves a whole neighborhood or MDU complex.

Typical specs: IP55/IP65, 144–576 fibers, locking, ventilation.

Wall-mounted vs pole-mounted vs pedestal

For most greenfield FTTH builds, the chain is: Central office ODF → Street cabinet → Pole/wall distribution box → ONT wall box → Subscriber ONT.

Splitter integration: cassette vs plug-in

Two common ways to install a PLC splitter inside a distribution box:

4.1 Cassette-style splitter

A pre-tested 1:8, 1:16, or 1:32 PLC splitter comes in a small cassette with input pigtail and output adapters already factory-installed. The technician simply slides it into the box and patches the drop cables.

Pros: Fast to install, factory-tested, low on-site failure. Cons: Less flexible if split ratio needs to change.

4.2 Plug-in / modular splitter

The box has empty slots; the technician plugs in splitters as needed. This is common in larger cabinets where subscriber counts grow over time.

Pros: Future-proof, pay-as-you-grow. Cons: More complex, higher upfront cost.

For most small-to-medium FTTH deployments, cassette-style splitters are the standard choice.

Splice capacity and fiber management

A good FTTH box needs:

• Enough splice trays — count the number of fusion splices plus 20% spare capacity.
• Proper bend radius — minimum 30 mm for standard fiber, 50 mm for bend-insensitive fiber (BIF).
• Slack storage — 1–3 meters of slack fiber per port, coiled neatly.
• Cable gland(s) — one for the input feeder, one for each output drop cable.
• Adapter panel — SC/LC adapters matching the rest of your network.

A box that is too small will force technicians to over-bend fibers or leave slack exposed, causing future signal loss.

Materials, ingress protection, and mounting

6.1 Housing material

• ABS/PC plastic — light, low cost, UV-treated for outdoor use. Good for most distribution boxes.
• Stainless steel — for high-security or harsh environments (coastal, extreme temperatures).
• SMC (sheet molding compound) — for large street cabinets.

6.2 Ingress protection (IP rating)

• IP40 — indoor only (ONT boxes, ODF).
• IP55 — protected against dust and water jets; suitable for wall-mounted outdoor boxes under eaves.
• IP65 / IP66 — fully dust-tight, water-jet resistant; for pole-mounted or exposed outdoor boxes.
• IP68 — submerged-rated; for underground splice closures.

Rule of thumb: if the box is exposed to direct rain, IP65 minimum. If buried, IP68.

6.3 Operating temperature

Specify −40 °C to +65 °C (or −40 °C to +85 °C) for outdoor enclosures. Cheap plastic housings become brittle in cold climates and warp in summer sun.

What to specify on a bill of materials

When ordering FTTH boxes, give the manufacturer:

1. Box type (distribution box / ONT box / splice closure / cabinet).

2. Mounting (wall / pole / pedestal / rack).

3. Input ports (how many feeder cables enter).

4. Output ports (how many subscribers / drop cables).

5. Splitter ratio (1:8, 1:16, 1:32) and style (cassette / plug-in).

6. Adapter type (SC / LC, UPC / APC).

7. IP rating (based on mounting environment).

8. Material (ABS/PC / stainless steel / SMC).

9. Mounting hardware (pole clamps, wall brackets).

10. Quantity and destination country (for certification — IP55/IP65 test reports).

At GYAPT, we ship FTTH boxes with splitter cassettes, adapters, and pigtails pre-installed so you receive a ready-to-deploy unit.

Frequently asked questions

Q: What is the difference between an FTTH box and a splice closure?

A: A splice closure only joins two cables (no split, no adapters). An FTTH distribution box splits one feeder signal into many subscriber outputs and provides adapter ports. They serve different points in the network.

Q: What IP rating do I need for a pole-mounted box?

A: IP65 minimum. Pole-mounted boxes are exposed to direct rain, snow, and UV. IP55 is acceptable only if the box is under an eave or sheltered.

Q: How many subscribers can one FTTH box serve?

A: Common ratios are 1:8 (8 subscribers), 1:16 (16), 1:32 (32), and 1:64 (64). For dense MDU buildings, 1:32 or 1:64 distribution boxes are typical.

Q: Can I install a PLC splitter myself inside the box?

A: Most operators prefer factory-prepared cassette splitters. On-site splitter installation requires fusion splicing equipment and testing, which adds labor cost. Ordering pre-loaded boxes saves on-site time and reduces failure rates.

Q: SC vs LC adapter — which should I use?

A: SC is the standard for FTTH in most markets (China, Southeast Asia, Middle East, Africa). LC is more common in enterprise/datacom environments. Match your ONT and patch cord connector type.

Need FTTH boxes for your project?

Tell us your distribution box type, port count, splitter ratio, and mounting environment. We will send factory-direct pricing and sample units.

• Browse: FTTH terminal boxes
• Related: PLC splitters
• Related: Fiber optic patch cords
• Contact: Request a quote

GYAPT — Qingdao Applied Photonic Technical Co., Ltd. OEM/ODM fiber optic manufacturer since 2002.