Airframe grounds

[cjensen]

What are your thoughts on airframe grounds? I have the central ground block on the firewall, as usual. Would grounding my recog lights and baggage lights away from that central ground on the airframe cause problems? I really don't want to run ground wires all the way back to the ground block from the wing tips, or even from the baggage area...

[rob]

Chad,

I used airframe grounds on my landing lights without any problems at all. Just avoid them with "noisy" devices and you'll be ok. What you are describing is perfectly fine for local grounds!

Rob

[Spike]

Ask a question, get a million answers.


I have decided to run grounds and power to all of my gizmos, especially ones in the wings. I like the idea of having a central grounding point for noise reasons. Though a main reason is that I can remember previous nightmares with using chassis grounds in cars. *ick*

Spike

[Brantel]

For plain old resistive non-active loads, this works fine and you should not have any problems.

For anything with active electronics in it, powersupplies, etc., I would use a common ground point. Also watch out for ground loops created when you have a separate ground wire running to a common ground and you also ground a device with a metal case by fastening it to the airframe. This one can be difficult to understand because some devices have an isollated metal case and some don't. If you can take an ohm meter and read continuity from the case to the negative power terminal, I would not ground the case and also run a long negative power lead back to the common ground point.

[cjensen]

I'm looking in to upgrading the lights to AeroSun Sunspots...would that be considered active electronics? If so, in this case I would want to run wires back to the common ground?

[Brantel]

Chad,

Hard to tell how they are driving those LED's but I bet they have an active powersupply in them. That being said, it is hard to know how well they have filtered these babies to prevent feeding back noise on the power lines.

Since I built my own NAV lights, and I am using a great filter on them, I am going to use an airframe ground on them.

[bullojm1]

I'm looking in to upgrading the lights to AeroSun Sunspots...would that be considered active electronics? If so, in this case I would want to run wires back to the common ground?

Chad-

I say use local grounds at first. If you hear any noise when you fly it will be pretty easy to run the extra ground wires later.

[cjensen]

Chad-

I say use local grounds at first. If you hear any noise when you fly it will be pretty easy to run the extra ground wires later.

Good point...

[Speed3Guy]

Here's a completely opposite viewpoint. Run ground wires for everything. Then you know there's not a problem and you don't have to think about it anymore.

Every pilot that has ridden in my plane comments about how quite the electrical system is. I probably just got lucky, but I think good grounding practice may have had something to do with it. I have no electrical noise. Not from wig-wags, LED position lights, strobes, flap motor, fuel pump. That's so unusual in GA aircraft that it actually stands out. It's one of those small intangible things that will make you so glad you built an airplane yourself using best possible practices. It's also something you can do for almost no money and only a little time.

Just on opinion of course. We're all picky about different things.

All that nonsense said--I grounded my resistive landing lights locally.

Cheerio,
Guy

[Womack2005]

Good comments. My plan is to locally ground pure resistive loads only. Everything else will get a ground wire.

[cjensen]

Good comments. My plan is to locally ground pure resistive loads only. Everything else will get a ground wire.

When you say this Will, I assume you mean everything getting a ground wire, will be run back to the common? Local would also use a "ground wire", but just a short run to local airframe...correct? Just to clarify...

[Womack2005]

Yep,

By Locally grounding I mean just grounding the ground lead to the airframe where the load is installed (like a nav light will just get grounded at the wing tip area).

Any load I'm afraid my gernerate noise will get a ground wire all the way back to the common airframe ground.

How far is it from the negative side of the ship battery to the common airframe ground? I haven't thought about this yet. It needs to be les the 3 milli-ohms, yes?

[cjensen]

Cool...that's what I thought you meant.

Battery to common ground is less than a foot...probably 8-9".

[bruceh]

There is a good article about wiring in the EAA Experimenter
http://eaa.org/experimenter/issues/0903.html
from March 2009. Scroll down to the Forum Review.

He makes a convincing case to run ground wires to everything.

BruceH

[jim_geo]

MTC. I ran out of space on my ground block also on the firewall. At the point that I ran out of space I was wireing for the wings and tail so I constructed another ground block and mounted it in the center section under the seat area then ran a single wire of proper gauge to the firewall for the ground. All of the grounds for all of the equipment go to the firewall ground block and then directly to the battery.

[smithhb]

I did the same thing. I used the block for my NAV lights and strobes. Good thing, too, because I couldn't squeeze another wire through the spar center section snap bushings!