Cables provide us the liberty of transmitting and receiving in between two electrical devices. Sometimes the electrical devices used in an industrial environment are placed in typically noisy environments. The noise factor becomes an integral part of the signal that is being transmitted through the electrical cable. Outer insulation of the cable does keep it safe from the environmental harsh hazards but could not keep the electromagnetic energy to merge with the noise factor.
Purpose of Drain Cable
One way to minimize the noise interference in the electromagnetic energy of the cable is through the use of shielding. Shielding provides two solid features i-e it reflects the energy and secondly, it can absorb the noise and send it to ground. But rather than attempting to ground the entire shield cable, the drain wire is used to terminate and ground the shield.
Drain Cable Construction
Drain Cable or a sewer cable is usually a foil shielded cable. A bare, stranded wire that is interleaved with the foil shield to provide a continuous, low-resistance connection in between the shield and the ground. Drain cable, sewer cable, drain snake is actually a name of the cable that can be installed in the drain and yet provides excellent conductivity throughout its length.
Drain cable is manufactured as a hard, high tensile, strength wire in a different variety of diameters. The diameters range from (1/4” to 3/4”) with corresponding lengths ranging from (37’ to 150’) or even customized according to the given specifications. Installation of drain cables matters a lot, that is why mostly these cables are custom designed according to the needs of their installation environment.
Instrumentation wiring practices
Following are some of the wiring practices which must be kept in mind in order to properly drain the extraneous noise to ground and keep it away from the circuit.
- First of all, there should not be any splicing in the cable. Splicing does provide the liberty of having easier installation but they are not worth the effort.
- Secondly, any wire that contains 120 volts can cause an electromagnetic interference, so any electrical machine or instrument present near to it is prone to get noise factor in it.