you need

- - Building roulette;
- - ammeter (tester);
- - caliper;
- - table electric conductivity of metals.

Guide

1

To find

**length****conductor**, a tape measure, measure the length of its individual sections and add them.This method is suitable for open wiring and measurement wires temporary cabling. 2

If the wiring is hidden, then to find the precise length of the conductor

**use the appropriate wiring diagram.If such a scheme is not, then try to recover indirect placing wires on the Status of plugs, switches, junction boxes, etc.featured.** 3

important rule linemen Note: All wires should be laid horizontally or vertically.Moreover, the horizontal sections of the wires usually run along the upper edge of the wall (the ceiling).However, the actual location of the wires can only define a special device or
an experienced electrician.

4

If you restore the path hidden wiring is not possible, measure the electrical resistance of individual sections of the conductor

**.For calculations specify the cross section of the wire and the material of which it is composed.This usually - copper or aluminum.Since the formula for calculating resistance: R = ρ * L * s, then****length****conductor**can be calculated by the formula: L = R / ρs, where: L - length**conductor**, R - resistance**conductor**, ρ- the resistivity of the material from which is made a conductor, s - sectional area of the conductor**.** 5

When calculating the length of a conductor

**consider the following parameters and sootnosheniya.Udelnoe copper wire resistance is 0.0154 - 0.0174 ohm aluminum: 0.0262 - 0.0278 ohms. (If the length conductor is equal to 1 meter, and the section - 1 mm²) conductor .Sechenie****equals: s = π / 4 * D², where: π - number of "pi" approximately equal to 3,14, D - diameter of the wire (which is easy to measurecaliper).** 6

If the wire is wound up on a spool, define

**length of one loop and multiply by the number of turns.If the coil has a circular cross section, measure the diameter of the coil (average diameter of coil, if multilayer).Then, multiply the number of diameter "pi" and the number of turns: L = π * d * n, where: d is the diameter of the coil, n - the number of turns of wire.**