MIL-DTL-24640/4 TTX and TTXWB Shipboard Cable

Mil-Spec Military part number MIL-DTL-24640/4 has two cable-type designations: TTX and TTXWB. The cable is rated for 600 volts and uses Standard Identification Code by Methods 1 or 3.  24640/4 cords use Extruded irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation and have a low-smoke zero-halogen (LSZH) cross-linked polyolefin (XLPO) jacket. The cable contains multiple conductors, with twisted pairs of two component wires, one black and one white twisted together to form a pair. The two conductors are insulated as discussed above and tested in accordance with SAE-AS81044/12 except that the identification will be according to MIL-STD-24640. The required number of pairs are cabled together with an optional binder tape and are enclosed in a cross-linked polyolefin (XLPO) jacket. These cords are lightweight and have non-flexing service. TTX is non-watertight and TTXWB is watertight. Both cables operate within a temperature range of -20°C to +105°C. Watertight cables can operate in a wide variety of situations, including through bulkheads and between decks. Non-watertight cables can be used within one or two continuous compartments, but are not permitted to penetrate bulkheads or watertight decks.

What does the cable designation TTX mean?

In the cable designation for TTX, the initial letter T refers to twisted pairs, the second T refers to two conductors per pair, and X refers to irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation.

What does the cable designation TTXWB mean?

In the cable designation for TTX, the initial letter T refers to twisted pairs, the second T refers to two conductors per pair, and W refers to the watertight nature of the cable.

M24640/4 Construction:

• Conductors:
  • Non-watertight: 19-strand tin-coated copper conductors
  • Watertight: 7-strand tin-coated copper conductors
• Insulation: Extruded irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation
• Jacket: Low-smoke zero-halogen (LSZH) cross-linked polyolefin (XLPO).

M24640/4 Ratings and Approvals

• Mil-Spec: MIL-DTL-24640
• Navy Shipboard Spec:
  • TTX for non-watertight
  • TTXWB for watertight
• SAE-AS81044/12 except that the identification will be according to MIL-STD-24640
• Voltage Rating: 600V

Features and Benefits of M24640/4 Cords

• Watertight cables can operate in a wide variety of situations, including through bulkheads and between decks.
• Cross-linked polyalkene/polyvinylidene fluoride insulation provides protection in environments with ultra-high vacuum, high temperatures, and ionizing radiation.
• LSZH jacket is fire resistant and emits low smoke, which is ideal for shipboard settings which often have restricted ventilation
• LSZH jackets also emit low acid, gas, and toxicity when subjected to fire, maintaining circuit integrity