Ask PYS: Power

Robert, on Jul 05, 2011 asked:

My battery monitor instructions say to use twisted pair wires. What are twisted pair wires and why are they important?

Hi Robert,

Twisted pair wires (sometimes referred to as simply “paired cables”) are what they sound like: two conducting wires twisted around each other. When installed properly, the twisted wires are able to reduce external electromagnetic interference (EMI) in the wire pair. EMI can come in many forms and is caused by various sources, for example, gas and electric motors or even other nearby wires (which is referred to as crosstalk). The disturbance may disrupt, block, or otherwise degrade the effective performance of the circuit. Instruments that measure very fine levels of voltage or current, like your battery monitor, use twisted pair wires to minimize this kind of interference. You will also find twisted pair wires for data communication and networking.

Twisted pair wires can also reduce the amount of EMI that the pair of wires produces. This can be useful if you have power wires (wiring for electric motors in particular) near magnetically sensitive devices.