Which construction accurately describes STP (shielded twisted pair) cable?

Which construction accurately describes STP (shielded twisted pair) cable?

• A. Three twisted pairs and no shield
• B. Four insulated copper pairs, each pair twisted with its own twist rate, with a metallic foil/shield around all, and an overall jacket
• C. Single pair with shield
• D. Five pairs with no jacket

Answer: (B)

Shielded twisted pair uses shielding to reduce interference while keeping multiple conductor pairs twisted for signal integrity. In this construction you have four insulated copper pairs, each pair twisted at its own rate to help cancel crosstalk between the pairs. Surrounding all four pairs is a metallic shield—often a foil or braided wrap—and the whole assembly is enclosed in an outer jacket. This shielding blocks external electromagnetic noise and keeps the cable’s own emissions from affecting nearby conductors, which is the key advantage of STP over unshielded cables. The other descriptions don’t fit typical STP: having only three pairs means one pair is missing; a single shielded pair describes a much smaller, single-pair cable rather than four pairs; and five pairs with no jacket doesn't match common STP constructions and would lack the protective outer jacket.

Shielded twisted pair uses shielding to reduce interference while keeping multiple conductor pairs twisted for signal integrity. In this construction you have four insulated copper pairs, each pair twisted at its own rate to help cancel crosstalk between the pairs. Surrounding all four pairs is a metallic shield—often a foil or braided wrap—and the whole assembly is enclosed in an outer jacket. This shielding blocks external electromagnetic noise and keeps the cable’s own emissions from affecting nearby conductors, which is the key advantage of STP over unshielded cables.

The other descriptions don’t fit typical STP: having only three pairs means one pair is missing; a single shielded pair describes a much smaller, single-pair cable rather than four pairs; and five pairs with no jacket doesn't match common STP constructions and would lack the protective outer jacket.