I work on MRI machines which use a lot of RF cables to transmit power and signals. There was one instance where a simple pressure switch with unshielded 2 wire cable was causing interference with the RF cables enough that it would inhibit scanning. After changing that one cable/harness for a shielded version the issue resolved. My cable had a ring terminal for the shield drain on one end, and then the metal DB9 connector housing on the other end provided ground there.
In military aircraft wiring, there are various methods. The two most common are actually grounding it on both ends of the harness run. Or solder sleeve it to wire/pin that later goes to ground.
@@vozhdmeister5256No, shields should be attached at both ends pretty much always. There are very few specialized exceptions. I would post a link, but often links keep UA-cam comments from getting posted. I will try to post in a second comment in case the url kills the comment. Both the military and FAA get this right, but almost everyone else gets it wrong.
Grounding both sides does not make sense. Your ground isn't just a ground, it's a conductor, it conducts the main power current. When you connect both sides of a shield to the ground you split the ground current with a part of current now flowing through your shield. As any conductor the shield has a resistance, so the current will induce a voltage drop, and your shield will start being an emitter of this ground signal. So you'll get an excellent emitter very close and all along the shielded cables. That's why the shield must be grounded at one end and at the reception end. It's possible that in military domain they create separated main power and low power grounds, in which case grounding both sides to the low power ground is safe.
I am working on extending a wiring harness for for my Lexus gs300 and a few of the cables are shielded with what looks like a lining of aluminum foil. Then there is what I assume is a ground cable with no sheath and a normal 22awg wire that I assume must be the main cable. Could I just mimic that when I’m extending it by using the same setup but with copper tape instead and then covered with shrink wrap?
We have never done that and would replace the cable as honestly, it will be much quicker and you won't be second guessing anything about that solution. Even though it's not what we would do, you can certainly try, noting you can route shielded cable through the likes of a bulkhead connector with success which is similar, in theory - Taz.
When using this method to run cam/crank sensors, should the grounds for the sensors be ran to the same sensor ground pin? And should the ground for the shielding be ran to the same pin as well? My ecu has two sensor ground outputs, I'm using one for the sensors themselves and the other was going to be used to ground the sleeving and the wires themselves if that's a good idea
The sensor ground needs to be run to a dedicated sensor 0v/ground pin (often there will be more than 1 sensor ground pin on the ecu). The shield should be terminated at the ecu end only and if there isn't a dedicated shield drain pin then this should go to the power ground pin - Andre.
@@hpa101 ecu master black have power ground. So I'll feed all the shield ground to that pin? Or can I just ground all the shield ground to engine ground?
Great information. Had to turn on CC, though, cause I have no idea what language he’s speaking. Its very bizarre, it’s like english, but with a bunch of funny sounding gibberish nonsense words thrown into every sentence.
These guys are awesome, I love their personality and skill level.
Sorry it took so long for us to reply but thanks for the support mate!
I work on MRI machines which use a lot of RF cables to transmit power and signals. There was one instance where a simple pressure switch with unshielded 2 wire cable was causing interference with the RF cables enough that it would inhibit scanning. After changing that one cable/harness for a shielded version the issue resolved. My cable had a ring terminal for the shield drain on one end, and then the metal DB9 connector housing on the other end provided ground there.
In military aircraft wiring, there are various methods. The two most common are actually grounding it on both ends of the harness run. Or solder sleeve it to wire/pin that later goes to ground.
Doesn't grounding the cable shield on both ends negate the purpose? Or did I misunderstand?
@@Nikoxion
Right, shields ground at one end only
@@vozhdmeister5256No, shields should be attached at both ends pretty much always. There are very few specialized exceptions. I would post a link, but often links keep UA-cam comments from getting posted. I will try to post in a second comment in case the url kills the comment. Both the military and FAA get this right, but almost everyone else gets it wrong.
Grounding both sides does not make sense. Your ground isn't just a ground, it's a conductor, it conducts the main power current. When you connect both sides of a shield to the ground you split the ground current with a part of current now flowing through your shield. As any conductor the shield has a resistance, so the current will induce a voltage drop, and your shield will start being an emitter of this ground signal. So you'll get an excellent emitter very close and all along the shielded cables.
That's why the shield must be grounded at one end and at the reception end.
It's possible that in military domain they create separated main power and low power grounds, in which case grounding both sides to the low power ground is safe.
Lolol that brade was putting up a fight 😂
What's your 'current' wiring project?
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I am working on extending a wiring harness for for my Lexus gs300 and a few of the cables are shielded with what looks like a lining of aluminum foil. Then there is what I assume is a ground cable with no sheath and a normal 22awg wire that I assume must be the main cable. Could I just mimic that when I’m extending it by using the same setup but with copper tape instead and then covered with shrink wrap?
We have never done that and would replace the cable as honestly, it will be much quicker and you won't be second guessing anything about that solution.
Even though it's not what we would do, you can certainly try, noting you can route shielded cable through the likes of a bulkhead connector with success which is similar, in theory - Taz.
How far should the shielding go on the sensor end?
When using this method to run cam/crank sensors, should the grounds for the sensors be ran to the same sensor ground pin? And should the ground for the shielding be ran to the same pin as well? My ecu has two sensor ground outputs, I'm using one for the sensors themselves and the other was going to be used to ground the sleeving and the wires themselves if that's a good idea
The sensor ground needs to be run to a dedicated sensor 0v/ground pin (often there will be more than 1 sensor ground pin on the ecu). The shield should be terminated at the ecu end only and if there isn't a dedicated shield drain pin then this should go to the power ground pin - Andre.
@@hpa101 ecu master black have power ground. So I'll feed all the shield ground to that pin? Or can I just ground all the shield ground to engine ground?
Where do we find those table clamps?
Great information. Had to turn on CC, though, cause I have no idea what language he’s speaking. Its very bizarre, it’s like english, but with a bunch of funny sounding gibberish nonsense words thrown into every sentence.
That's exactly what it is 😎 Glad the captions helped, we refrain from throwing gibberish in those too - Taz.
Where do we find those clamps?