Wire run planning in a RV7

[mruffatto]

Hello,
I’m getting setup wiring and have come up with some questions.
I’m building an RV7.
VPX Sport
2 – Dynon SV-D1000T
1 – Battery Backup
1 – Adahrs mounted aft of baggage area on shelf
1 – Engine Module
2 – Dynon Comm Radios
1 – Dynon Intercom
1 – Dynon Trasnpoder mounted aft of baggage area
1 – Dynon Adsb mounted aft of baggage area
1 – Dynon pitch servo mounted aft of baggage area
1 – Dynon roll servo mounted right wing
1 – Dynon heated pitot
1 – Dynon GPS Reciever not mounted yet
1 – Autopilot control panel
AeroLeds lighting

I need some advice on routing some wire runs. I foolishly riveted my floor panels in place without installing a conduit run. The center tunnel is going to be a very popular place. I currently have the pitot and angle of attack lines in the tunnel on the pilot side running aft of baggage area and up to adahrs.

My initial plan for the aft baggage area components are as follows. Transponder will have its own run up the tunnel and to the back of the panel. Same for the ADSB I planned on connecting the pitch servo to a serial hub. Run the power lines separate. Connect the adahrs to the serial hub and have just one network cable running forward. Roll servo would be ran to the panel by itself.
What if I do not use the hub? Adahrs will get its own run forward. Pitch servo will run over to wing root connection terminal block and tie in with roll servo. From there it will run forward of the spar to the back of the panel. Better idea? I’m still not convinced of using a wing root connection so I’m open to other ideas.

I understand skyview can be on during engine start. So should I just set the Vpx to have those always on? What should avionics master control? Comms, intercom, transponder, adsb ?
Should the autopilot servos have a dedicated power switch on the panel?

Would it make sense to run an extra wire to the transponder now for possible future connection of a certified gps?

Thanks
Mike

 

[mruffatto]

In an effort to reduce wiring to the back of the plane is it possible to have the transponder and adsb use the same power run?

 

[dynonsupport]

Mike,
The VPX requires the EFIS to always be powered anytime the VPX has power. Since the VPX is controlled by the EFIS, it's kind of pointless to have the VPX on without the EFIS. I don't think you can even configure the VPX otherwise.

You might want to reconsider the transponder and ADS-B in the back. You can put them up under the panel, and if you do that, you have only one coax to run for each, instead of 4 wires. Most of our customers do this. Admittedly, a coax is larger around than 4 22ga wires, so if diameter is your biggest issue, the rear located devices may make the most sense.

There's no issue sharing power with ADS-B and transponder, only the small edge case that if one were to short, you lose the other as the breaker goes. They are each very low power so any wire can handle both loads. Note that you can also ground these devices locally to the airframe so save a ground wire going forward.

The hub will reduce wiring in the center tunnel significantly, so I'd suggest using that in the back to join the pitch servo and the ADAHRS. You can also just use a splitter since you only have two connections back there.

The servos should have their own power switch in case something happens. If you didn't have a VPX you can use pullable breakers, but with the VPX you need to dig into a menu in SkyView to disable circuits and you want something quicker than that.

 

[mmarien]

If you have several items in the back that require power, run one power wire back and place a fuse box back there for the individual items. Check the VP-X manual 4.12a What if I run out of power pins?. Just note that if you have the power wire switched, all the devices will power up or down with the switch.

You don't really have to decide what is turned on with the avionics switch now. The power pins or any combination can be programmed to any switch so you can change your mind later without rewiring. One of the best benefits of VP-X.

There is a specific pin (J12-9) to power the EFIS. As Dynon noted, the EFIS or one of them is power on when VP-X is powered.

Nice list of equipment.