Proper cable shield grounding practice

Don M

I hope someone can answer this.

Using a Dallas temp sensor though a shielded 3 conductor cable (DC+, DC- & Data) inside a machine. The cable will run parrallel to other low voltage AC & DC cables. For the remaining end of the cable where the sensor is located it is mounted inside of a small refrigeration system.

Should the shield be grounded only on one end such as the end where it connects to a microprocessor board?

Presently it is grounded at the beginning where it connects to the micro board and then the other end is tied to the DC- at the temp sensor end along with the DC- conductor in the cable. Doesn't seem quite right to me but that is why I am asking. I think the shield should remain disconnected from the DC- at the sensor. By the way, the DC- and the micro board ground are at the same potential.

Can anyone help here?

Thanks.

Phil Pilgrim (PhiPi)

Yes, ground the shield at one end only. Otherwise, you will have current running through your shield, which will compromise its effectiveness.

-Phil