How large should the tray in a fiber optic splice plastic case be?

Answer: Size it from the slack. A 120 mm tray holds 3.5 m for 12 fibres, a 240 mm tray 14 m for 48, with 5 mm to the foam.

Is an IP67 rating enough without a pressure test?

Answer: No. The rating is a type test, not every unit. Inflating each case to 30 kPa for 60 seconds catches a twisted gasket or unseated latch.

Can two latches hold a 48-fibre case?

Answer: Only under 600 mm. Above that the lid edge lifts, so four latches are needed or the pressure test fails.

Routed foam or laminated foam?

Answer: Route from one block for a splicer or an OTDR, where plus or minus 0.5 mm protects the housing. For sleeves, a laminate is enough.

What lead time should be expected?

Answer: About 20 days with an existing tool, plus 25 to 30 for a new one. At 300 units, moulding takes about 5 days of that.

Fiber Optic Splice Plastic Case: 5 Selection Criteria

Quick answer: A fiber optic splice plastic case is chosen on five measurable points: tray bending radius, gasket compression, latch and drop behaviour, foam retention, and price against the installation window. All five can be checked on a sample in an afternoon.

Fiber Optic Splice Plastic Case: Start With Bend Radius
Seal Compression and Air Pressure Test
Latch Count and Drop Height
Foam Inserts That Hold the Splice Trays
Cost, Lead Time and What to Trade
FAQ

1. Fiber Optic Splice Plastic Case: Start With Bend Radius

A fiber optic splice plastic case is judged first on its slack tray radius, not wall thickness. Single-mode fibre is coiled at 30 mm; G.657 allows 15 mm, but splice slack is still coiled at 30 mm. A tighter tray loads the fibre permanently.

Coil a real pigtail in the sample, measure it, add 20 mm of clearance, keep a 5 mm gap to the lid foam, and pick the tray from the fibre count, not the shell.

Tray diameter	Slack capacity	Fibre count	Typical use
120 mm	3.5 m	12	Drop cable entry
180 mm	8 m	24	Floor distribution
240 mm	14 m	48	Branch backbone
300 mm	22 m	72 and above	Room termination

2. Seal Compression and Air Pressure Test

Gasket compression decides whether the case is watertight. Nitrile and silicone seals run at 40 to 50 Shore A: below 20% it never seats, above 35% it takes a set.

Fiber optic splice plastic case in pale grey, open, black cable coiled in a loop, grey module and white bottle beside it, white handle

Inflate the closed fiber optic splice plastic case to 30 kPa, hold 60 seconds, accept a drop under 1 kPa. Ports, latch seats and handle bosses leak most, since each puts a hole in the wall. Retest at -20 °C after 4 hours, while the gasket is stiff.

3. Latch Count and Drop Height

Latch count follows case length: below 600 mm two latches at 150 N hold the lid flat, past that four share the load at 110 N.

Drop at 1.2 m onto six faces, then check lid shift beyond 1 mm, latches that opened, and corner cracks; an 8 mm radius resists it better.

Latches	Pull force each	Lid shift after drop	Case length
2	150 N	0.6 mm	Under 600 mm
2 plus centre catch	130 N	0.9 mm	600 to 800 mm
4	110 N	0.4 mm	Above 800 mm

4. Foam Inserts That Hold the Splice Trays

Inside the fiber optic splice plastic case, trays, sleeves and tools each need a pocket, or movement in transit pulls finished splices apart. EVA at 30 kg/m³ or PE at 35 kg/m³ works, cut 1 mm undersize so interference holds the part.

Fiber optic splice plastic case corner in white, blue foam along the wall, a black square panel seated in the cutout, flush edges

Routed from one block, pocket tolerance holds at plus or minus 0.5 mm, suiting a splicer or OTDR. A laminated stack costs 30% less but opens along the glue line. The lid pad compresses the foam about 20%.

5. Cost, Lead Time and What to Trade

A 30% spread between quotes is normal, driven by wall, insert process and tooling. Moving from 3.0 mm to 3.5 mm adds 12% to material, and 80 kg on the lid for 24 hours sags a 3.0 mm shell over 2 mm.

Existing tools ship in 20 days; a new tool adds 25 to 30 days. With a fixed window, take a slightly thinner standard case rather than betting on a mould.

Check	Tool	Pass value	Time
Tray radius	Tape measure	30 mm minimum	2 minutes
Air pressure	Pump and gauge	30 kPa held 60 s, drop under 1 kPa	15 minutes
Latch pull	Force gauge	110 N minimum	8 minutes
Foam pocket	Calipers	1 mm smaller than the part	6 minutes

Conclusion

The decision comes down to five numbers measurable on a sample: tray radius, gasket compression, latch and drop result, foam retention, and price against lead time. The first four decide whether the box works; the fifth decides whether the project lands on schedule. That is the whole method behind specifying a fiber optic splice plastic case.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.