Shielded wire question

by David J. Beaulieu

Oct 25, 2013

Query to the group...

 

Running 3 conductor shielded wire from the wingtip strobes (AeroLED NSP).

Shield / strobe / base grounded near outboard wing tip.

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The three conducting wires for the strobe/nav unit (and fuel sender) from wing will be routed into the fuselage through a Molex type connection. .

 

Question:  What to I do with the grounded shield wire?  Only two options I see are: (1) ground the shield wire at the wing root and call it "good", or  (2)  Continue routing the ground into the fuselage dash area via the Molex type connector for eventually grounding near dash switches.

 

Hope the question is clear, if not, ask away to help me rephrase.

 

Dave

 

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  • up

    David J. Beaulieu

    John / Mark

     

    Thanks for the replies. 

     

    John - Good point about the low voltage thru the lines, everything is "stepped up" via the IC boards at the strobe unit on each wingtip. I will have to check out the wiring diagram, but I believe the AeroLED schematic shows the shield grounded at each end of a continuous run of wire from strobe/nav unit to switch.  I placed a call to AeroLED but missed the tech call back so will try to connect next week.  I used a solder seal with a grounding termination wire to affix a ground to the shield and then grounded to the spar/wing tip extension via rivet.  I had planned on continuing the ground thru the quick connect at the root/fuselage into the panel and also ground to a dedicated ground bus behind the panel within the fuselage.

     

    Mark - Thanks for the pic.  Seems like you are in agreement with John regarding grounding of the shield.  You are grounding at each individual run of wire but not continuing the shield continuity across your Molex.  Is my understanding correct?

     

     

    Will post wht I hear from AeroLED...  Thanks again!

     

    Dave

    3

    Oct 26, 2013

    • up

      Daniel C Hall

      It's been said already but once again, ground one end of the shield only.  Both ends of the NEGATIVE conductor of course need to be terminated.  

      Oct 26, 2013

      • up

        David J. Beaulieu

        Follow-up to the shielded wire question... I talked with Dean Wilkinson,CTO of Aeroled regarding the schematic for grounding the shield...very personable and seems knowledgeable regarding E&M and application. Schematic indicated grounding of the shielded wire at the wing tip in close proximity to the strobe/nav unit and at the other end of the wire run. Based on his experience, he suggested that I adhere to the schematic and ground at both ends.  Only if I have an issue with an on board magnometer should I consider grounding at one end only, and is so, ground inside the fuselage, vice the wing spar tip.  Also did some browsing on the Van's RV site and the EAA site regarding this topic.  Opinion seems to be split down the middle depending if you are shielding to protect comm freqs or different areas of the spectrum?  So for now, I will plan on continuing the ground thru the quick disconnect into the fuselage and ground at the common ground behind the dash.  I guess worse case would be I make an access panel at the wing tip and disconnect the shield ground there.

        Nov 4, 2013