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Induction loop cable installation

Prior to installation, it is important to check if there will be any equipment in the vicinity that may interfere

with the loop's magnetic field, such as large transformers, high power cables or substations. It is also

important to ensure that no equipment will be adversely affected by the loop field, such as sensitive data or

signal cables. In these cases, it may not be possible to cover some or any of the required area with an

induction loop.

The cable gauge will depend upon the total length of the induction loop. Usually, the loop will be installed

around the perimeter of the listening area. However, there are various techniques which can be employed to

build arrays to vary the shape and strength of the field. In general, calculations outlined here are based upon

a perimeter installation.

It is recommended to use good quality insulated pure copper cable for the induction loop. The cable gauge

used will need to be determined by the total length of the cable run. The LA-series loop amplifiers are

designed to operate with a load of between 0.2Ω and 2Ω. The following equation can be used to calculate

the total cable resistance, which will show if the gauge is correct.

R =

Cable length (m)

Cable CSA (mm²)

So, for a cable 80m long with a Cross-Sectional Area (CSA) of 1.5mm²...

So, this gauge of wire (1.5mm²) would be OK for the 80m run because it is between 0.2Ω and 2Ω

As a quick reference, refer to the table below.

Cable CSA (mm²)

Total Loop Length

The wire may be run in plastic conduit but not in any metal containment so as not to impair the magnetic

flux. The ideal height to install the cable depends upon the width of the loop (i.e. the narrowest dimension

relative to the listener). The optimum output will be achieved if the cable is installed 14% of the loop width

higher or lower than the plane of listening (ear height).

In practical terms, the loop is usually installed onto skirting boards, under flooring or at ceiling height so that

it is unobtrusive. It is recommended to avoid varying height levels as much as possible to avoid anomalies in

field strength.

For irregular shaped areas or larger than the loop amplifier's capacity, multiple induction loops may be

required for coverage. Connecting further loop amplifiers using the Slave connection will enable multiple

loops to be used together.

x 0.01786Ω*mm²/m (specific resistance of Copper)

1.0

60m max.

110m max.

R = 80/1.5 x 0.01786 = 0.9525Ω

1.5

2.5

200m max.

4.0

Over 200m

952.864UK, 952.867UK User Manual