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The Official Table of Drops, formerly issued by the British Home Office, is a manual which is used to calculate the appropriate length of rope for long drop hangings. Following a series of failed hangings, including those of John Babbacombe Lee , a committee chaired by Henry Bruce, 1st Baron Aberdare was formed in 1886 to discover and report on ...
The resistance of copper wire is approximately 1 ohms / 1000 feet for 10 AWG, 10 ohms / 1000 feet for 20 AWG, 100 ohms / 1000 feet for 30 AWG, and so on. [ 5 ] : 27 Because aluminum wire has a conductivity of approximately 61% of copper, an aluminum wire has nearly the same resistance as a copper wire that is two sizes ...
Wire gauges may be broadly divided into two groups, the empirical and the geometric. The first includes all the older gauge measurements, notably the Birmingham gauge (B.W.G. or Stubs) and the Lancashire. The origin of the B.W.G. is obscure. The numbers of wire were in common use earlier than 1735 when the measurements were officially defined. [1]
A cable in this usage cable is a thick rope or by transference a chain cable. [1] The OED gives quotations from c. 1400 onwards. A cable's length (often "cable length" or just "cable") is simply the standard length in which cables came, which by 1555 had settled to around 100 fathoms (600 ft; 180 m) or 1 ⁄ 10 nautical mile (0.19 km; 0.12 mi). [1]
Aluminium conductor steel-reinforced cable (ACSR) is a type of high-capacity, high-strength stranded conductor typically used in overhead power lines. The outer strands are high-purity aluminium , chosen for its good conductivity, low weight, low cost, resistance to corrosion and decent mechanical stress resistance.
Steel wire rope (right hand lang lay) Wire rope is composed of as few as two solid, metal wires twisted into a helix that forms a composite rope, in a pattern known as laid rope. Larger diameter wire rope consists of multiple strands of such laid rope in a pattern known as cable laid. Manufactured using an industrial machine known as a strander ...
1000 circular mils = 1 MCM or 1 kcmil, and is (approximately) equal to: 0.5067 mm 2 , so 2 kcmil ≈ 1 mm 2 (a 1.3% error) Therefore, for practical purposes such as wire choice, 2 kcmil ≈ 1 mm 2 is a reasonable rule of thumb for many applications.
Typical values are 1.04 for roller bearing sheaves and 1.09 for plain bearing sheaves (with wire rope). [11] The increased force produced by a tackle is offset by both the increased length of rope needed and the friction in the system. In order to raise a block and tackle with a mechanical advantage of 6 a distance of 1 metre, it is necessary ...