Grounding Shielded Sensor Cables Question

[PMD24]

I have the Vintage Gauges and am using their sensors and cables for feeds to the water temp and oil pressure gauges. The wires are shielded but the ground wire is cut off at both ends and is inside the insulated sleeve. I thought that for a shield to work it needs to be grounded, and if not grounded, it can actually act like an antenna and make signal interference worse. Can anyone tell me why the ground wire is tucked away and not used for grounding?

I can follow up with Vintage Gauges on Monday, but I was starting work on shortening the gauge feeds when I came across this, and would like to keep working on it over the weekend. I spoke with Vintage Gauge a couple of weeks ago about shortening the leads and they said it would be fine. Didn't know about the shielding wire at the time so didn't ask.

Thanks,

Pat

[Nigel Allen]

Grounding of the shield wire is not required in this application, as the voltage levels between the senders and gauges is high enough not to be affected by interference. I'm not sure why this manufacturer chooses to use shielded cable in these applications, but you can just ignore the shields. If you decide you really want to ground the shields, then you only do it at one end. Otherwise, The shield can end up carrying current which cause more interference.

All ground wires should be bought to a 'star point'.

Hope this helps

Nige

[JJK]

shielded cables usually have a drain wire on one end to ground. not sure why they do not, but as nigel said, only one side should be grounded else you risk ground loop interference. interesting to hear why they chose not to leave the drain wire accessible.

[Nigel Allen]

shielded cables usually have a drain wire on one end to ground. not sure why they do not, but as nigel said, only one side should be grounded else you risk ground loop interference. interesting to hear why they chose not to leave the drain wire accessible.

As a wild guess, I reckon it might be more about the cable construction (having a double insulation layer offers better protection and it presents well). Plus, if they do need to shield a signal, say a transducer or something like that, then they can just use the same cable...

Cheers,

Nige

[rich grsc]

If they needed a ground pigtail, they would have one.:rolleyes: Worrying about a non-issue

[PMD24]

Thanks everyone. I'll leave it as-is.

Nigel, for my own education, what do you mean by the term "star point"?

[StangRacer]

Thanks everyone. I'll leave it as-is.

Nigel, for my own education, what do you mean by the term "star point"?

obviously, not Nigel but I will offer the little bit of knowledge I have regarding grounding. Hopefully, Nigel will see this and provide his expertise...

A "star point" ground is when all grounds run to a single point. This eliminates ground loops. When you put grounds at several different locations on a common ground different levels of conductivity may exist causing current flow.

[Nigel Allen]

Stangracer and Rich are right on the money.