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  #1  
Old 01-13-2021, 08:33 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
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Default Reducing Circuit Breaker Count

It seems the Garmin G3X system has a lot of fuses/ circuit breakers for the various boxes.
How do I combine the fuses / circuit breakers together to reduce the number in the system?
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  #2  
Old 01-13-2021, 08:44 PM
BobTurner BobTurner is offline
 
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Remember the fuses/breakers protect the wires, not the electronics. So if you have 10 boxes that each draw 5 amps, you could put in one 60 amp breaker and use fat wires (maybe awg 9 gauge?) to everything. But do you really want that? Thatís a lot of fat, heavy wires. And if one of those 10 boxes or their wires fails to ground, the breaker will trip and all ten boxes will go off. Not usually desired.
OTOH, if you have a lot of low current, non-essential boxes (maybe an intercom, an FM radio, a dome light, a cell phone charger, each of which draws 1/2 amp) go ahead and put them on a single 5 amp breaker, as long as all the wires are rated for 5 amps or more.
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  #3  
Old 01-14-2021, 09:04 AM
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Raymo Raymo is offline
 
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I used a 12 position fuse/ground block behind the panel and a hand full of CBs for things I wanted more control over (AP, Flaps, etc.). Saved a lot of space and $$.
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  #4  
Old 01-14-2021, 09:36 AM
rocketman1988 rocketman1988 is offline
 
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Default Vpx

The vpx will replace them all...
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  #5  
Old 01-14-2021, 09:55 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by rocketman1988 View Post
The vpx will replace them all...
And in this app a $17 fuse block will replace a VPX.

https://www.steinair.com/product-cat...s/fuse-blocks/
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  #6  
Old 01-14-2021, 09:56 AM
PilotjohnS PilotjohnS is offline
 
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Default Good idea

Quote:
Originally Posted by Raymo View Post
I used a 12 position fuse/ground block behind the panel and a hand full of CBs for things I wanted more control over (AP, Flaps, etc.). Saved a lot of space and $$.
This is a good idea. I could put things on fuses that I dont plan to reset in flight. Let me think about this. Thanks for the suggestion
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
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Wings 98% done
Fuselage Kit 98% done
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Electrical 65% in work
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  #7  
Old 01-14-2021, 09:56 AM
AlpineYoda AlpineYoda is offline
 
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Quote:
Originally Posted by rocketman1988 View Post
The vpx will replace them all...
What are people's experiences with vertical power and similar devices?

Replacing all the circuit breakers with a single point of failure seems like a design flaw to me, but maybe I'm missing something. The ability to pull a circuit breaker when something goes wrong is an idea that goes back to George Westinghouse. Replacing all your breakers with something that depends on software and microchips seems like we are introducing another point of failure, and one that will catastrophically affect everything in the plane.

Don't get me wrong - I love the idea of elegant solutions. Aveo wingtips will replace a bunch of individual lights on my plane. G3x and G5 will replace six packs, vacuum tubes, and standby instruments. But replacing the ultimate safety device in the event of a short, electrical fire, or other emergency with a black box that kills every circuit in the plane when it fails seems wrong to me.

What am I missing?
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  #8  
Old 01-14-2021, 10:39 AM
JDA_BTR JDA_BTR is offline
 
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I used an 8-place auto fuse block for LEMO power, 12V adapter, USB jack, etc. It is a good solution and works great. I'll put more of my avionics on same next time.
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  #9  
Old 01-14-2021, 12:17 PM
DRMA DRMA is offline
 
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I believe it is much better to protect each LRU with a circuit breaker or fuse, rather than tying several of them together, so that you only lose a single LRU in the event of an electrical supply problem (short, open circuit, etc.).

One additional advantage to circuit breakers vs. fuses is the ability to open the circuit easily. So for example, if you are trying to reduce electrical load to extend battery time in the event of an alternator failure, you can pull the breakers on non-flight essential equipment (second display, second radio, audio panel, transponder, etc.) to reduce system draw. Most of the G3X devices do NOT have on/off switches, so the only way to shut them off is to remove power to them. It is also useful in testing and trouble shooting while on the ground to be able to easily cut power to individual devices.

So it's not just about being able to reset breakers while in-flight.

Regards,
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  #10  
Old 01-14-2021, 12:21 PM
salty salty is offline
 
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Location: FL
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Default

Quote:
Originally Posted by BobTurner View Post
OTOH, if you have a lot of low current, non-essential boxes (maybe an intercom, an FM radio, a dome light, a cell phone charger, each of which draws 1/2 amp) go ahead and put them on a single 5 amp breaker, as long as all the wires are rated for 5 amps or more.
...assuming the total draw for all of them on at once will be less than 5 amps...
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