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Where to mount ground tabs block in -8 or -8A

Bubblehead

Well Known Member
I am redoing some wiring in my -8 and have a rats nest of grounds going to a terminal block. I'm considering moving the ground wires to a new ground tabs block as described in The AeroElectric Connection. Because of the forward baggage compartment on the -8 it seems impractical to mount the block on the firewall.

So where do people mount their ground tabs block on an -8 or -8A? Pictures would be especially helpful. Did the location work well or would you put it somewhere else if you had it to do again?

Also, did you mount terminal blocks somewhere for avionics power or lighting power? If so, where did you mount them and did they work well there.

Thanks,

John
 
Scott - that area is baggage area in my plane, which I use whenever my wife and I take a trip. What you've done sure makes wiring easier though, and does provide a good place for the battery!

I like where you put the wiring blocks a lot. It makes them easy to get to and a short wire run from the aux electrical panel on the right side of the plane.

Ratman - if I understand you correctly, the ground tabs are above the boost pump?

Another question for both of you - there does not seem to be many things to ground on the firewall side.
 
right gear tower

Here's where I (originally) put mine.

http://www.rv8.ch/engine-and-electrical-system-grounding/


Probably not the best place, it seems. Most of my ground wires are up behind the panel, so I ended up running a bunch of ground wires down to this "forest of tabs". I'll probably end up moving it.

Update: I will move it, not 100% sure where yet.
 
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Mickey,

It looks like you're using the area forward of the right gear tower for wiring and perhaps the battery, much like Scott is doing. Right now mine is set up for baggage but I may have to change that.

Thanks for the photo. It gives me an option.

John
 
Not sure how this is wired

The following was done with the ground cable disconnected from the battery.

I spent the afternoon under the panel trying to straighten out the mess and figure out what the terminal blocks are for. It turns out there are three separate blocks. Two are hooked together and are grounded to the airframe. The third terminal strip is confusing me.

I figured that the third strip would be an avionics buss but to verify that I hooked up my ohm meter between the main buss and the terminal strip and found that I had continuity between the two regardless of the position of the avionics master switch!

That seems to mean that anytime there is power to the main buss there is power to this other small buss, which means whatever loads are attached to the small buss are hot when the master goes on. This could also mean these loads and their wiring are not protected by a circuit breaker or fuse!

The wires attached to the small buss disappear into the rats nest and a wire bundle so I was not able to trace them.

Does anyone have any idea what loads might be attached to this small buss?

I took some pictures of the terminal strips that I'll post later tonight or tomorrow.
 
Ratman - if I understand you correctly, the ground tabs are above the boost pump?

Another question for both of you - there does not seem to be many things to ground on the firewall side.

No, it's exactly the same as Scott's except it's on the opposite side of the aircraft. Scott's is on the right side, mine is on the left. His is MUCH easier to get to and I almost did the same thing but I didn't want to give up the storage. (edit: John, I noticed you have an IO-360 so yes, it would be above your boost pump on the firewall. I have an O-360 so my boost pump is farther back near the gear tower.)

There isn't a lot on the front of the firewall to ground unless you are using electronic sensors like the ones Dynon uses. I might have 5 or 6 sensors grounded there without counting. I could have grounded them to the firewall but just seemed easier and neater to use the ground block.

Scott, how did you label the shrink tubing? I just spoke with Stein about this but his machine is a bit to expensive for me. 99.9% of my wiring is done but that is the way to go! Really nice:cool:
 
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Ah-ha

Well I made a breakthrough on my understanding today. I spent a couple of hours at the hanger, pulled the instrument panel out part way, and was able to really figure out what the three terminal strips mounted on the right gear tower do.

7 posts are for ground wires
3 posts are for panel lighting
3 posts are for the instrument panel AND the starter solenoid circuit.

The third one is the way Vans schematic shows it.

Once I figured out how it was wired things got easier. I was able to straighten out a lot of wires. I don't think I'll change the location of the ground terminal strip, but I will change the wire routing to the engine compartment for alternator and magneto wires.

Thanks to those who posted info, ideas and pictures. Seeing what you guys have done helped a lot.
 
You can make up paper labels on the computer, and use clear heat shrink over them.

Cheap, simple, easy, and look good.
 
You can make up paper labels on the computer, and use clear heat shrink over them.

Cheap, simple, easy, and look good.

Yea, that's exactly how I did mine and they're OK but...Scott's are the same as Stein uses on their harnesses and they look great and are easier to read.

If I do it again I'd beg Stein to print a bunch for me. If that didn't work I would remind him that I aint broke yet! That would drive him nuts.
 
Dymo RhinoPro 5000

A year ago I bought a Dymo 5000. Very impressive for it's features, and it's available at this link for $87.

http://www.labelcity.com/eonline/itemdesc.asp?ic=15517

It's not very intuitive to use, but I made a couple of cheat sheets so even when I don't use it for a while I can get things done without having to figure it all out again.

The tape for shrink lables is expensive. The 1/4" size is $30 for 5' of label. The 1/2" is too big for most wires in an RV but fits over tab and ring connectors. The 1/4" is fine for our wires but doesn't fit over tab and ring connectors. The end result is unless you have wire without a connector on it you will have a hard time retrofitting these shrink labels.

There is also a heavy duty Nylon tape (not shrink-tube) which costs about $20 for 11'. Despite what the website says, it does not seem to stick really well, even on clean wires under the panel. I think the problem is the label is just a little too stiff to roll over the small wires in our planes.

On the plus side - the black on yellow is very visible and looks sharp but I'm not sure it's worth the price. I think knowing what I do now I would get some yellow paper and print a bunch of labels on the computer and laser printer, then use clear shrink wrap to attach the label to wires.

John
 
Left Side Firewall Ground Block

I'm bumping this thread as I'm looking for a single, good location for the forest-of-tabs ground blocks, brass bolt, and engine-side firewall ground location and also for the engine monitoring wiring to feed through (for my Dynon SV-EMS-220).

Since most of my RV-8A's firewall aft-faces the forward baggage compartment or the rudder pedal area, I've decided my only option is on the lower left side of the firewall. That area is pretty busy with the fuel pump, heater valve, and aft battery cable and looks like it'll get even busier later with control cables and who-knows-what on the engine side.

Can anyone post a picture of their setup showing both sides of the firewall so I can de-conflict future problems? I like the look of Scott Chastain's photo in posting #3 except I want to utilize the lower left side. And I'd like to see if there will be any obstacles on the engine-side later.

Thanks,
Joe
 
Grounding block

I have decided that I am going to fabricate a false floor in the bottom of the baggage compartment on the right side of the aircraft. My plan is to seat the false floor on the forward longeron and install a angle with matching slope on the inside wall of the baggage compartment. This will allow the forest of tabs to be mounted low on the firewall but take up a minimum of space in the compartment. The false floor will be removable and leave about 3 to 4 inches of space under it for the ground wires...any comments on this plan?
 
Luke - That looks like a good place for it. It keeps the baggage well open and usable and it is not in the area where there are fuel lines. Four questions:

1) It is hard to see from the picture but it looks like there is a bolt that goes through the firewall to the engine side. Does the engine ground connect to that same bolt?

2) Do you have a firewall mounted battery or an aft battery?

3) Are you running a fat ground wire from the terminal block in the pictures to the battery?

4) Is there any possibility of contact with the rudder pedal? I would not want the rudder pedal to damage the ground wires going to the block.

John
 
Left side of firewall works

Forest of tabs from B&C

Interior view
cabin%252520side%252520ground.jpg


Firewall View

firewall%252520side%252520ground.jpg
 
John

1) It is hard to see from the picture but it looks like there is a bolt that goes through the firewall to the engine side. Does the engine ground connect to that same bolt?

2) Do you have a firewall mounted battery or an aft battery?

3) Are you running a fat ground wire from the terminal block in the pictures to the battery?


I've a firewall monted battery (Odissey PC680), the bolt shares ground battery cable, gnd engine case and the ground tab.

4) Is there any possibility of contact with the rudder pedal? I would not want the rudder pedal to damage the ground wires going to the block.

NO, there are not possibility of any contact !

Pics here :

http://www.rv8.it/log/chronological/eight/Pages/42.html

http://www.rv8.it/log/chronological/eight/Pages/58.html

John[/QUOTE]
 
Another option

Sometimes I sacrifice function for the sake of organization. I isolated the mounting of a B&C block. Behind panel where it is needed. Preserving the baggage area for something important like a smoke oil tank....

Running #6 out to firewall mounted battery and airframe ground. I don't have a real grasp on the ground loop phenomenon but will only ground one end of wire shields.



 
Opinions Wanted

I'm in the initial stages of planning out my wire runs, and I'm looking for feedback on my proposed location of the forest of tabs grounding block. I don't want to give up the lower forward baggage space if I can help it, and I don't like the Van's proposed frame grounding bolt location due to potential interference with the rudders if I installed a FOT there. (I'm 6'2" with size 13 rudder pushers.)

What I'm thinking at the moment is to place the main FOT on the left side of the firewall between the throttle/prop/mixture cables and the fuel line. (48 tabs on the cabin side, 24 tabs on the engine side.) That will keep the wires away from my feet and preserve the baggage hold for baggage. I'm going to mount the battery on the firewall, so this will require a heavy grounding cable from the battery on the right side of the FW to the FOT on the left, but I think that's an acceptable solution given my other concerns.

I'm also considering adding an insulated avionics FOT (single sided, 24 tabs, similar to what Blain made in the previous post) and mounting it to the F-866A Bulkhead above the brake line F-866D Mounting Plate. (I'm planning a G-3X, GTN 650, G-5, GTR 20, GTX45R set up.)

I made cardboard FOT templates and taped them into position. In the first photo, the main is circled in blue and the avionics is circled in red.

full


Avionics FOT:
full


Main FOT, cabin side:
full


Main FOT, firewall side:
full



Do any of these planned locations interfere with other requirements or any other issues with mounting FOTs in these locations?

Thanks in advance,
Rob
 
forest of tabs

...

What I'm thinking at the moment is to place the main FOT on the left side of the firewall between the throttle/prop/mixture cables and the fuel line. (48 tabs on the cabin side, 24 tabs on the engine side.) That will keep the wires away from my feet and preserve the baggage hold for baggage. I'm going to mount the battery on the firewall, so this will require a heavy grounding cable from the battery on the right side of the FW to the FOT on the left, but I think that's an acceptable solution given my other concerns.

I'm also considering adding an insulated avionics FOT (single sided, 24 tabs, similar to what Blain made in the previous post) and mounting it to the F-866A Bulkhead above the brake line F-866D Mounting Plate. (I'm planning a G-3X, GTN 650, G-5, GTR 20, GTX45R set up.)

...
The avionics ground is a good idea - I'm going to do it like the Aeroelectric connection recommends and use a DB-25 for that.

For the tabs, your location near the fuel pump seems like it will not be that easy to access once the F821PP is installed. Not impossible, but not easy.

My current (new) plan is to have a small FOT on the front of the FW, and have one behind the panel, with the ground wires running from the FW side FOT battery ground.

I'm trying to keep as much wiring away from the fuel pump area.
 
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Rob, I see you also have an access door in the fwd baggage area to reach the rear of the instrument panel.
Here is what I did:
I mounted several cable blocks including a ground block on the rear side of the access door. Now when I open that door there is very easy access to the wiring as the cable blocks are laying right in front of you. I also put stickers beside them showing which circuit is each wire connection. Two wires (for redundancy) are going from the ground block to the firewall.
PM me if you like to see pictures. Sorry can?t post pics because of the Photobucket issue.
 
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