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garmin gap 26 pitot (heated and regulated)

S

SeanM

Member
I'm installing the garmin gap 26 pitot (heated and regulated) and going off the G3X touch install manual. I'm just wiring to the wing roots at this point.

It looks like I'll need to go with unshielded 12 gauge for the main power.

I'm not sure what gauge I'll need for the regulator discrete output (blue wire). Coming out of the regulator it's 22 gauge. I'm not seeing in the manual anything about draw on the blue wire. Am I safe to assume I can use 22 gauge?
 
I pulled a 22 wire and just about at the same spot in my build. If you read in the g3x manual it just shorts to ground as a signal wire so no need for anything thicker.

Working on figuring out the other wires for servo currently. How many and what size. I swear I have to think 20 steps ahead sometimes!
 
It'll be fine

Sean, it will draw milliamps, so 22 gauge will be absolutely fine. The clue is in the name "discrete output", details of which are in section 26.5.9 of the G3X touch manual.

When the probe is on and hot, this wire is connected to ground (0 volts) by the GAP26 controller. The GEA24 or GAD27 (whichever one you connect the blue wire to) can sense when that wire is at (or close to) 0 volts and it uses that to detect whether the probe is hot or not.
 
be aware

I have been talking to the avionics shop and they recommended 14 AWG wire for the pitot. If you are using a VPX, I do not believe the 12 AWG wire will fit the connector...

Here are the expected current requirements:

Probe Temperature/Amps
-40?C (-40?F)/ 12 Amps
0?C (32?F)/ 9.25 Amps
50?C (122?F)/ 7.3 Amps
100?C (212?F)/ 5.85 Amps
175?C (347?F)/ 4.36 Amps
 
rocketman1988 said:
I have been talking to the avionics shop and they recommended 14 AWG wire for the pitot. If you are using a VPX, I do not believe the 12 AWG wire will fit the connector...

Here are the expected current requirements:

Probe Temperature/Amps
-40?C (-40?F)/ 12 Amps
0?C (32?F)/ 9.25 Amps
50?C (122?F)/ 7.3 Amps
100?C (212?F)/ 5.85 Amps
175?C (347?F)/ 4.36 Amps
Click to expand...

I used a AWG 14 and 15A breaker. That -40F/C is the start up amperage, not the steady state.
 
Ok thank you everyone for setting me set straight. Will go with 14awg for the pitot (I am planning on vertical power). I will also continue the discrete line with 22awg.


I was able to get the left landing light wired, pics here: https://imgur.com/a/Uo8v51w
 
I guess I was the most conservative here, and went with 12ga shielded (M27500-12TG2T14) for this - for the total distance, since I'm not grounding locally, Vans actually recommends 10ga. I got shielded mostly thinking that I didn't want it to interfere with my wingtip NAV antenna (if I'm at a very low temp needing pitot heat, there's a good chance I'm in the soup or about to be).
 
The G3X Installation manual has the following note in section 5.5.2:

Notes for 14V Installation: Aircraft power wiring to probe should be minimum 14 AWG up to 12 FT, 12 AWG from 13 to 20 FT, and 10 AWG from 21 to 30 FT.

Depending on your wiring, many RVs will fall right around the 12 FT length. Remember, a fuse or circuit breaker is there to protect the wiring, not the unit. Even though the normal draw of the GAP 26 is quite a bit lower than 15 amps, you need the wiring size to be sufficient to pop the circuit breaker before melting anything.

Thanks,
Levi Self
 
I used a 12 AWG twisted pair with Deutsch connectors at the regulator and at the wing root. I did that because of the run length which is greater than 12 ft as Levi says.
 
Exactly, and remember that if you're running the ground back to a central grounding block you need to count the full length (from power source to device to ground).

Mine was at about 21ft total, so I gave myself some margin and went with the 12.
 
About the connector, I'm using TE AMP CPCs from their series 4, which has both high-current and low-current pins. (assuming that the connector, being ~close to the fuel lines, would be the worst place to have a fire start).
 
12?

So I assume that those using the larger gauge wire are not using a VPX?

If you are, how did you get the #12 wire to work with the VPX pin?
 
and...

I have been speaking with the avionics folks and apparently the #12 will not fit the VPX terminal, which has a maximum wire size of #14.

#14 wire will carry 15 amps continuously with an acceptable temperature rise and no smoke.

Couple that with the given distance in the -10 of right at 12 feet and a maximum current draw for the GAP26 of around 12 amps and it is reasonable to use #14 wire...

Certainly nothing wrong with #12 if you can make it work, though...
 
rocketman1988 said:
I have been speaking with the avionics folks and apparently the #12 will not fit the VPX terminal, which has a maximum wire size of #14.

#14 wire will carry 15 amps continuously with an acceptable temperature rise and no smoke.

Couple that with the given distance in the -10 of right at 12 feet and a maximum current draw for the GAP26 of around 12 amps and it is reasonable to use #14 wire...

Certainly nothing wrong with #12 if you can make it work, though...
Click to expand...

This is where I'm currently stuck. Was thinking of putting my GMU 11 magnetometer on the left wing. Issue I'm concerned with is the interference from the pitot power ( as Rodrigo mentions). This means twisting the ground wire back to at least the wing root if not farther into the fuse. Which leads to needing a larger wire and incompatibility with the VPX (at least out of the box). UGH!
I guess enough people have had success mounting the GMU 11 (or 22) in the tail so that's my next thought. Feel like I'm driving myself nuts trying to pre-plan and run wires earlier in the build and may just have to wire as best I can and then make adjustments as I get near the finish line. Appreciate all the info everyone is sharing.
 
Well...

As previously posted, I am doing my avionics wiring. The avionics shop has, based on their experience with the rv-10 installs, recommended installing the GMU22 in the tailcone, one bulkhead behind the baggage area bulkhead.

They are also recommending #14 wire for the pitot.

I specifically asked about the GMU placement and they said that the vast majority that have been installed in this location have had no issues. Though there have been some installs that have not worked in the tailcone, it seems to be due to the individual aircraft rather than the general location.

I am accepting their recommendations based on their experience with these installs. Once operational, I will post another data point...
 
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