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"Forest of Tabs" Ground Location...

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idleup

Well Known Member
Does anyone have photos or links to URLS that show some good places to mount the grounding block from B&C on the firewall?
 
idleup said:
Does anyone have photos or links to URLS that show some good places to mount the grounding block from B&C on the firewall?
Click to expand...

Best photo I can find right now shows the "forest" on the right side of the aircraft. It's a little hard to see in my photo. It worked well for me. I used the RV-7 Van's firewall plans on my RV-6. The interior side has the same ground forest tabs as the firewall side. Probably overkill but the interior one is almost full. I ran separate grounds for everything. YMMV

30iexjp.jpg



Found a better photo

2yvwgmd.jpg
 
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I could show you my photos (they are on mykitlog), but you really want to find another rv7 with similiar accessories that you are planning. What other things hanging on the firewall or in the vicinity will dictate the best location.

Bob
 
I put mine on the firewall right behind the radio stack. My rationale was for access as the radio stack is the only major cutout I have in my subpanel -- that's the theory anyway. ;)
 
I put mine on the interior of the firewall, up high and near the center (over the battery).
IMG_3394-M.jpg


You can see what is on the other side (engine side of firewall). Plenty of room for the cowling hinge pins. Engine ground strap comes to the stud on the far right. Battery ground goes to the larger stud on the forest of tabs ground block.

IMG_3233-M.jpg
 
There are likely a lot of good spots to mount the FOG, and its not an expensive item, so why not mount one. I asked this question early on, but waited until my electrical, instrumentation, and engine monitoring firmed up. During designing my system and choosing the components, I kept an eye on the Fwf grounding requirements. Well, my dual Dynon Skyview with Ems is fully installed and operating, ie, all electrical is complete. Not a single Fwf ground other than the common point on the firewall for the battery and engine ground anchored with a bolt. My assumption is that a lot of the need for Fwf grounding may be pre-glass panel/ EMS. I do have a large FOG behind the panel with probably a dozen tabs used, but none Fwd.
 
I put mine above the battery on the upper portion of the firewall. I do not have any tabs on the forward portion of the firewall, couldn't see any use for them. Although not showing in the picture, I have quite a bit of my electrical run now and it is working out well so far.

FP09122012A00054.jpg


FP09122012A00053.jpg
 
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Will I have any need for the big brass bolt on my FoTs?

My RV-8 has a complete Dynon SkyView system going in, and I'm trying to position the B & C 48-tab grounding block in my avionics bay for ease of installation and future mx. I'm picking up from other posts that I will not have many ground wires FWF, so am not too concerned about mounting my FoT on the aft side of the firewall, where the bolt could be of use on the engine side. Instead I want to put in on the aft side of my baggage bulkhead, forward side of the left gear tower, or maybe on a z-bar?but can I attach it without the huge brass bolt? If the bolt head is protruding in the baggage compartment, I see it as a scratch & rip source for whatever goes in & out of there. I'd like to replace it with a shorter round-head bolt, unless someone tells me I'll need to attach heavy ring terminals to it.
 
I put mine in exactly this location as you describe. Looking forward, on the left side of the baggage bulkhead. This way I can reach the ground tabs from my baggage window behind the panel so it will possible to get to in the future. I ended up keeping the big bolt, just leaving the head on the baggage side, I plan to use a large terminal and run a heavy gauge ground wire forward to the firewall and use another bolt passthrough. Attaching the engine grounds on the forward side of that bolt. I'll try and get a picture this weekend and post it.
 
The "forest of tabs" detail in the Aeroelectric book is actually for composite aircraft construction. I think it is a good idea to be as robust as possible with your grounding and it certainly wont hurt to pass through the tab with a large ground stud, but these are metal airplanes guys.
Keeping the grounds clustered and ground path short is a great idea to reduce ground loop potential problems. However, a forest of tabs does not buy you much mounted on the firewall in the engine bay..... there is not that much to ground on that side.
Keep you forest where you need it, on the inside of the firewall or other metal structure, close to the electronics you are grounding. Per plans your battery ground should already be bolted to the firewall close to the battery.
 
You can put it anywhere you want, however the objective with the "forest of grounds" is to bring ALL the grounds to the same place to help avoid ground loops. They can be really fun to try and track down. This is the risk you accept when you have grounds going to a couple of different places...

The large bolt is to connect the forward and aft of firewall grounds, including engine and battery grounds.

Here's a couple of shots of my -8. It was really easy and so far no ground loops have raised their ugly heads...

Good luck

This shot shows battery and engine grounds (large white wires) to the "big bolt". You're right, not many other grounds firewall FWD, but they all go to the same place unless instructed otherwise (eg. P-Mags).



This shot shows grounds aft of firewall, wrapped in spiral wrap and tie wrapped to the engine control cables

 
Very Few FWF

I'm not convinced of the need to mount and entire tree of tabs FWF. There are very few ground wires FWF. Most could be done with only a few tabs or ring terminals to s carry through bolt. Keep it neat, keep it simple.
 
Thanks for feedback

Thanks for sharing, guys. I should have also said that I'll have an aft battery and I'm installing the VP-X system. I plan to run ground wires back to Fot from nearly all loads.
Happy Building.
 
Mine is mounted in about the same location as yours. The trick is getting the battery out. Since you have a-6, this may not be an issue.

Like others have mentioned, FWF I only have two connectors.

On the aft side of the firewall is a bigger forest and it is full.

I used a brass bolt to tie them together along with the ground cable from the battery and another cable for the engine ground.
 
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