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How do I use this

Av8torTom

Well Known Member
Bought this grounding block, but I'm not sure how to use it. What are all the stacked washers for on the left? Thanks

 
My guess on the washers - in case you have something thick to go through and needed a longer stud for that, and for for attaching more than one ring terminal from various ground blocks in the airframe - like battery and engine ground strap on the firewall. Heavy ring terminals should be captured between a couple of those washers. The second hole is probably only there to hold the terminal block in place.
 
washers

I think washers were stacked just to keep track of them so they didn't get lost.

Find a place on the inside of the firewall above the battery and drill holes then bolt (using supplied bolts and washers) the grounding block to the firewall.

It becomes the common ground for all the electrical components and avionics.

It should be placed such that it can be accessed readily, but not accidentally.

The negative lead from the batter on the engine side of the firewall connects to one of the through bolts.

You will have many wires connecting to it when finished.

Steve
 
There's a hundred different ways to skin this cat - but the goal is to make sure all your grounds have a good way to dump lots of amps and stay at the same potential.

I used two pieces of heavy copper buss bar on either side of my firewall, with two large brass bolts through the bars and the firewall holding them together, and tied my engine ground to it on the hot side of the firewall and my battery ground to it on the cold side (my battery is aft of the baggage compartment). This gave me good solid grounds on both sides and grounded the airframe to it in the process, I've not had a single ground issue in 300 hours so far.

http://websites.expercraft.com/airguy/index.php?q=log_entry&log_id=75632
 
Ground block

I bought one of these too and asked myself the same question. Because most of my grounds from lights are grounded locally at the light and all the other ground wires came back to the VP-X.

But I used it and it was helpful.

I had to ground the battery to the firewall, so I drilled a hole thru the firewall and put this on the cabin side of the firewall. That's what the big bolt and all the washers are for. You can bolt the ground strap from the battery to it on the engine side. Then as I finished my wiring there were a couple of ground wires that needed grounding. So I put a blade connector on them and shoved them on one of the blade studs. I only used about 3 of the blades, but oh well. They are grounded.
 
Ground block

I bought one of these too and asked myself the same question. Because most of my grounds from lights are grounded locally at the light and all the other ground wires came back to the VP-X.

But I used it and it was helpful.

I had to ground the battery to the firewall, so I drilled a hole thru the firewall and put this on the cabin side of the firewall. That's what the big bolt and all the washers are for. You can bolt the ground strap from the battery to it on the engine side. Then as I finished my wiring there were a couple of ground wires that needed grounding. So I put a blade connector on them and shoved them on one of the blade studs. I only used about 3 of the blades, but oh well. They are grounded.
 
I used one of these on my 7A. I ran a ground wire from every electrical point of use back to this type of grounding block. I did not trust that the airframe was the ground. It worked fine for me. Yes I used more wire than necessary, but I had no radio interferences, or unstable light connections.
 
I used one of these on my 7A. I ran a ground wire from every electrical point of use back to this type of grounding block. I did not trust that the airframe was the ground. It worked fine for me. Yes I used more wire than necessary, but I had no radio interferences, or unstable light connections.

Same here. Every single thing on my plane grounds to the forest of tabs on the cool side of the firewall and then that post grounds to my engine cradle and the engine itself.
 
I bolted my forest of tabs to the firewall with a AN5 bolt and nut on each side. Is it standard practice to use brass hardware?
 
This is what it looks like in my installation.

Firewall side. Eventually when the engine went on, I used the other mounting bolt to hold the ground strap for the engine.

IMG_3697-M.jpg


Interior side. Every circuit comes back to here, with just a few exceptions where some lighting circuits were locally grounded to the airframe.

IMG_3745-M.jpg


You don't need to use every washer they provide! I have some internal tooth lock washers also in there for security on the main ground and engine ground bolts.
 
This particular "forest of tabs" is designed for use in metal or plastic airplanes, hence the long thru bolt which would be necessary if you didn't have a metal firewall. Aeroelectric book shows the install for a plastic airplane, which uses the stud to the battery ground strap thru the firewall. While not necessary with a metal firewall, it sure can't hurt and makes for a very clean installation.
I put my tabs elsewhere and trust my airframe for ground with exceptions as called out by each component manufacturer.
 
I have a suggestion: Label all the ground wires that you attach to that gizmo. You can thank me later :D
 
Here's mine, all loaded up. The bolt goes through the firewall to tie to the battery ground point

i-gXcPTMn-M.jpg
 
I have a suggestion: Label all the ground wires that you attach to that gizmo. You can thank me later :D

Where's the giant "LIKE" button when you need it most?!?!
Yup, knowing which ground wire does what is just as important as knowing which power wire does what. Sage advice there from snopercod!
 
Thanks everyone

I'm thinking of running another wire from the firewall battery ground to the subpanel and mounting the grounding block on the subpanel where it should be easier to get to. Any reason not to do this?
 
That's a fairly common practice. To really eliminate the risk of ground loops, some of us isolate that 2nd ground block from the airframe and run a fat ground wire back to the primary forest of tabs. One technique for the subpanel ground block (which typically has only low current stuff attached) is to use a female subD connector with all the pins soldered together. A male subD housing made for removable pins is screwed to the chassis-mounted female, and each ground wire gets a crimped male pin. Very small & light weight.

Charlie

(Join the Aeroelectric list and you'll see all of the above illustrated.)
 
I'm thinking of running another wire from the firewall battery ground to the subpanel and mounting the grounding block on the subpanel where it should be easier to get to. Any reason not to do this?

I did this exact thing. My forest of tabs was "too big" so I cut it. 2/3rds on the firewall and 1/3 on the back of the panel, with a good tie from it to the mother on the firewall. As long as you have a solid tie back to your single point ground, you should be good.
 
This is what it looks like in my installation.

I put my FOT in nearly the same location on my RV-9A as Bruce.

But mine is a slider, so I'm not looking forward to the footwell yoga that will be needed to trace future ground issues when and if required.

I'd locate it lower on the firewall if I did it over again.
 
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