How to measure wire length

How to measure wire length

Calculation of cable length or wire at its use in the large volume and impossibility of measurement is from beginning to end made by tape measure in drum. After that the received result is compared with length, necessary at mounting.

It is required to you

  • - rope;
  • - wedge clip;
  • - set of tools of the electrician;
  • - bandage (collar);
  • - theodolite (t-30, t-20, tt-50, tt-5);
  • - steel tape measure (RS-10, 20, 30, 50).


1. Count distance at which it is necessary to make mounting of the line (for example, electricity transmissions), summarizing length of intervals between support (columns), distances between subjects to transfer and the first columns at the beginning and at the end, necessary increments for mounting on support and the connected objects.

2. Find length of the wire which is reeled up on drum, considering that such method has errors as it is applied at incomplete drum (if any quantity of wire was already used from this hank) or in the absence of designation of cable length sideways on drum cheek. Measure drum neck length. If it is impossible, find it in the special table where to certain number of drum there corresponds the length of neck. Measure its diameter (too is in tables), inside diameter on the reeled-up wire and diameter of cable. Put the received values in formula: Lp = 3.14*lsh * (2dv – 2dsh) / 4*2Dk, where Ln – the required length of wire, Lsh – length of neck, Dv – diameter of the reeled-up wire, Dsh – diameter of neck, Dk – diameter of cable.

3. Determine the necessary length of wire between columns, using eye estimation. Observing safety measures (using safety harness and the electrician's "claws"), fix the free end of wire for armature with insulators by means of coupling armature. By means of rope and wedge clip pull wire between columns, adjust it has sagged and impose bandage. Lower wire on the earth, measure from bandage length of two fittings with insulators and if it is necessary, chop off and mold. This way labor-consuming also demands big expenses of time, is applied in the absence of geodetic tools.

4. Measure the necessary length of wire, using geodetic devices. Take theodolite (TT-50) and make distance projection between fastenings for wire on columns or other support. Measure steel tape measure the received distance between projections. Add necessary length for dip and increment for mounting.

Author: «MirrorInfo» Dream Team