Shielded or not??

[Electrogunner]

Have read a couple articles about aircraft wiring and have come to the conclusion of use shielded wire on anything comm, data or audio related. Anything else can be non shielded ie, le nav postion lights,trim motors, flap motors,pitot heat, led interior lighting. I'm using led nav/ position lights so don't have any high volt power packs to give off EMI. All coax will be triple shielded ECS 311601 appears to be really good stuff and kept away from power circuits as much as possible. I am planning on bringing all grounds back to 1 or 2 locations, 1 behind baggage and 1 behind panel. Are my thoughts correct on these observations.

 

[Auburntsts]

Suggest you use shielded for your LED NAV lights too. The LEDs can be an RFI source.

 

[rv7charlie]

1. Aeroelectric Connection

2. LEDs are rarely a guarantee against EMI; most use 'switching' power supplies which may or may not have proper EMI abatement.

3. Aeroelectric Connection

4. Shielding of power/signal wires rarely does much to affect electrical noise abatement in a/c.

5. Proper grounding (*single* point) has far more effect than any shielding of power/signal wires.

6. Aeroelectric Connection

7. Proper fabrication and installation of coax used for RF is essential to keeping RF out of other electronics.

8. Did I mention Aeroelectric Connection?

Charlie

 

[Raymo]

Shielding has two purposes.

1. Keep EMI out
2. Keep EMI in

As mentioned above, LED lights can create EMI so you use it for purpose 2. Radio/Comm use it for purpose 1.

If shielding is done incorrectly, it can cause more harm than good by acting as a receiver/antenna for EMI.

 

[622BH]

EMI vs EMF

EMI = Electro-Magnetic Interference (this is the bad stuff you don't want getting into your circuits.) Thus the need for using shielded cable.

EMF = Electro-Magnetic Force (this is the good stuff you want to keep in and moving toward the antennae.) Thus the need for shielded cable.