G3X grounding (power and ground)

I tried to send an email to [email protected] and it got bounced back.
Here's my question:

The manual says it's best to ground (power ground) all LRUs together at the same place - no local grounding of LRUs. Also the CAN bus shield should be grounded at each backshell on the LRUs.

Should I also ground the power cable shield to the backshells? Also, should this shield for the power be grounded at the same place I will ground the ground wire from all the LRUs?

I am supplying power and ground to all LRUs with a 2 conductor 22AWG shielded cable. To clarify, I'm asking if this cable shield should also ground to the backshells or should this be kept separate from the grounds for CAN bus and RS232 signal wires?

Thanks!

Why use shielded power and ground?

I wired my G3X system per Stein and did not have any callouts for power and ground wires. They were run as separate unshielded wires. All the LRUs were grounded to the same ground block mounted on the inside of the firewall and all the power cables ended up at the fuse blocks. I would not have been able to do this if I used a shielded cable since the ground block and fuse blocks are located several feet away from each other. I don't believe there is any reason to shield the power and ground since there is no data flowing. I only used shielded wires for data and audio wires. I have zero issues with interference.

Kentsrv7a said:

I wired my G3X system per Stein and did not have any callouts for power and ground wires. They were run as separate unshielded wires. All the LRUs were grounded to the same ground block mounted on the inside of the firewall and all the power cables ended up at the fuse blocks. I would not have been able to do this if I used a shielded cable since the ground block and fuse blocks are located several feet away from each other. I don't believe there is any reason to shield the power and ground since there is no data flowing. I only used shielded wires for data and audio wires. I have zero issues with interference.

Click to expand...

I agree with Kent.

IF you do use a shielded power & ground cable, the shields can all be daisy chained together so that the CAN, RS232, and power shields are all jumpered to one wire that goes to the backshell.

Yep!

That is how I did it also Power and Ground wires do not require shielded wires.

Thanks gentlemen, that makes things much clearer.

Nothing wrong with using a shielded pair for power/ground. I will do this for for two reasons, ease of installation (feeding thru conduits etc.) and for additional protection when I can't properly support/clamp the wires due to limited access. I usually ground the shield at the LRU end and leave the other end open.

Thanks Walt. I did get a response from one of the G3Xperts but he did not understand that I was asking about grounding power lead shields. I since decided to just run plain wires to the servos anyway. Haven't started on the other LRUs yet.