What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

firewall forest of tabs

R

rockbottom

Active Member
For the electrical gurus:

In my RV8, with an aft mounted battery and an IFR panel, I've installed a B&C 48 tab ground block on my firewall, and in an attempt to as much as possible utilize a single grounding point, I foresee that I will run out of tabs. A couple of wing mounted items will be grounded locally, and a few other items that are mounted in the rear of the plane will be connected to an aft mounted isolated ground bus which in turn, will be grounded to the airframe. Still, I'm going to be short of tabs up front. I have a smaller 24 tab block on hand and was thinking of mounting it adjacent to the larger block on the firewall. Forgive me if this is a dumb question, but would the two grounding blocks need to be connected in any way other than their attachment to the firewall? (The bonding strap from the engine is connected to the mounting bolt of the 48 tab block and I have an additional bonding strap bolted directly to the firewall.)

Thanks in advance for your help,

J Baker
Fayetteville, GA
 
can also use these on half your ground wires:
SA-003-BLU-FAST-ON-W-TAB-L-600x600.jpg


which basically doubles the number of tabs.

from Stein (and possible other places):
http://www.steinair.com/product/14-16-ga-blue-faston-14-2/
 
Adding a second set of tabs is not a problem. If you want you can make mount the second set of tabs on the next aft bulkhead, connecting that set to the first via a #10 wire (connected to the main ground lug).

As alternative, you can reduce the number of tabs being uses by combining the ground wires in one tab. You can get about (3) #20 wires or (2) #18 wire in a blue tab.

If you ground your wing stuff locally, remember to run a ground wire from your tab block to a ground point on each wing.

Carl
 
jwilbur said:
You might also be able to buy some more tabs on the existing block with these:
http://www.steinair.com/product/14-16-ga-blue-faston-14-2/
Click to expand...

Good tip - wasn't aware these existed. Just keep in mind that using these or other methods of combining grounds means that if it comes loose, you have now lost multiple devices instead of just one. I would suggest minimizing these single points of failure and/or limiting their use to devices that are not critical.

erich
 
I was running out of tabs too, though I was starting with a 24 tab unit. I bought a 48 tab version, but instead of replacing the existing one and moving all the connections over, I cut the 48 tab piece in half, cut/ground off some tabs around an existing hole and mounted it overlapping the already installed FoTs. You may be able to do something similar.

IMG_5268.jpg
 
Carl Froehlich said:
Adding a second set of tabs is not a problem. If you want you can make mount the second set of tabs on the next aft bulkhead, connecting that set to the first via a #10 wire (connected to the main ground lug).
Click to expand...

This is what I did...mostly for grounds from all the LED lights in the switches. My design philosophy was for each individual circuit/load to have its own power and ground, all grounds coming back to the FOT, which led to a *very* full 48-tab FOT on the firewall.

It was amazing how much wire I actually ended up with in the plane at the end, but labelling each end of each wire, along with the single pwr and gnd for each circuit, has made maintenance easy (what little I've had).
 
Grayforge did it right by identifying each ground wire. You'll be sorry if you don't (ask me how I know).
 
You must log in or register to reply here.
Back
Top