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G3X Engine sensors and shielded wiring

nickwj

Member
Hi, I'm across in the UK building an RV9A with an IO320 engine. I'm wiring up the G3X engine sensors to the GEA24 and I've realised I've made a mistake.

The Kavlico pressure senders are supplied with 16awg tails (unshielded) so I went ahead and spliced in the extra 16awg wire to reach the GEA24. I now realise that the manual says they should be shielded, floating at the sensor end and grounded to the backshell at the other, but over here I can only source 18awg 3 core shielded wire - would that be suitable?

I'm also aware that the Dynon kit uses unshielded wires so would it harm if the above stayed unshielded. Unfortunately, I can't find a builder over here who has fully installed a G3X system.

All comments and help/advice will be welcome.

Nick
G-RVWJ
 
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I connected my Kavlico sensors with 22 gauge shielded wire - works fine. The manual (rev v, section 27.1, note 3) states that 24 gauge is the minimum unless otherwise called out.

I suspect unshielded wire would work just as well.............
 
Ditto:

We have a full G3X tough system with all the boxes but GNT-650. We did the same as Mark above did. Bought a roll of 3 stand 22 AWG shielded and a roll of 2 strand 22 AWG shielded and used them to wire most everything in including the C.A.N. buss. The only place we did not use it on the system was power and ground to all the boxes. We used 20 AWG red and black unshielded for those. Your on the right track with this one. It works just fine. Hope this helps. Yours, R.E.A. III #80888
 
Unshielded sensor wiring

I have had good success using unshielded wire for the engine sensors only, in multiple G3X installations. This is the only place I have deviated from the Garmin install manual.
 
Hi, I'm across in the UK building an RV9A with an IO320 engine. I'm wiring up the G3X engine sensors to the GEA24 and I've realised I've made a mistake.

The Kavlico pressure senders are supplied with 16awg tails (unshielded) so I went ahead and spliced in the extra 16awg wire to reach the GEA24. I now realise that the manual says they should be shielded, floating at the sensor end and grounded to the backshell at the other, but over here I can only source 18awg 3 core shielded wire - would that be suitable?

I'm also aware that the Dynon kit uses unshielded wires so would it harm if the above stayed unshielded. Unfortunately, I can't find a builder over here who has fully installed a G3X system.

All comments and help/advice will be welcome.

Nick
G-RVWJ

Hello Nick,

While we appreciate that some report having good success using non-shielded wiring on engine sensors, that is not always the case. I know I used to have non-shielded engine sensor wiring in my homebuilt and would see many of the engine sensor readings change when transmitting on the 10W COM radio. The fuel flow reading would also get hammered and change when transmitting.

There have been no problems anywhere since I converted to shielded wire on everything with properly grounded shields.

You can wire most, if not all the signal wiring in a G3X system with 2 or 3 conductor shielded wire. The CAN bus uses 2 conductor and powered sensors like the Kavlico pressure sensors which need power, ground, and signal use 3 conductor.

Section 2.3 in the G3X Installation Manual tells you to use 22 gauge MIL-W-22759/16 for all connections unless otherwise specified.

If you search ACS or other vendors sites for MIL-W-22759, you will find that 22 gauge 2 and 3 conductor shielded wire is readily available (at least in the U.S.).

For power and ground wiring you will want to mostly use unshielded 22 AWG MIL-W-22759 wire. You will also need a little of the heavier 20 AWG wire for some of the power/ground connections on things like the transponder and 10W COM radio.

It isn't common to use heavy 16 AWG or 18 AWG wire, especially for G3X devices.

Thanks,
Steve
 
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Sorry.

I did not address the fact that you wanted to use a heavy Gage shielded wire, sorry. Steve is a good guy he is almost always right. And we have had good luck and pricing from a company called B&C down in I think Oklahoma.
They have most anything you would need to do a wiring job for the newer IFIS systems. Hope you have good luck finding this stuff over on the other side of the pound, if not it is here in the states waiting for you. Yours, R.E.A. #80888
 
Thanks for all the help and advice.

What was throwing me was splicing 22awg shielded wire onto the 16awg tails on the Kavlico sensors - I assumed they were 16awg for a reason and that the step between them and 22awg was so large there would be a knock on effect somewhere else.

So could I just confirm splicing those two different gauge wires together is acceptable?

I have sourced shielded wire from gps.co.uk and they have been helpful - they supplied my G3X system. I went ahead and used 18awg shielded wire - will this be a problem?

Cheers

Nick
 
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So could I just confirm splicing those two different gauge wires together is acceptable?

Should not be a problem.

I went ahead and used 18awg shielded wire - will this be a problem?

No problem for the electrons :). The only problem will be trying to get an 18awg wire into the pin for the GEA24 connector. I believe the largest wire size that will fit is a 20awg.
 
Should not be a problem.



No problem for the electrons :). The only problem will be trying to get an 18awg wire into the pin for the GEA24 connector. I believe the largest wire size that will fit is a 20awg.

..........and I've just walked back from the workshop this very minute having discovered exactly that! :( ....the pins I have will not fit 18awg!!!

So, the answer must be, as everyone has said, go with 20 or 22awg shielded.

I know there are far more interesting threads than this but if it helps someone in the future then its been worth it!

Thanks everyone.

Nick
 
Splicing the wires

I am curious to know how you guys connected the 16 and 22G wires together.
The transducers have clip on connectors that can be removed to unscrew the transducers, so there should be no need for a molex type connector (Not true for the RPM sensor on magneto where I used molex connector).
Thanks.
Johan
 
It's likely they used the heavier wire on the sensors to make them more sturdy at the sensor. Joining to a thinner wire should be fine. There isn't much current flow in that type of circuit and that is what determines the required size of the wire.
 
I trim a few strands from the sensor pigtails until they will fit into a red 22-18 butt splice, then I splice them together.
 
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