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Terminal Blocks

skelrad

Well Known Member
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I put terminal blocks in place for my connection between the wing and fuselage wiring. Do I need to use Loctite on these screws? The terminals seemed like a very straight forward solution to making the connection from the wings, but if I'm wrong and it's a terrible idea, I'm all ears.

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I put terminal blocks in place for my connection between the wing and fuselage wiring. Do I need to use Loctite on these screws? The terminals seemed like a very straight forward solution to making the connection from the wings, but if I'm wrong and it's a terrible idea, I'm all ears.

View attachment 75701
Won't debate the use of the block but connector(s) would have been easier IMO. If you stick with this approach, the screws should have some locking device as they are in blind holes.
 
Do we need a removable connection for the wing wiring? If you need to terminate them at the root solder sleeves or high quality butt splices are pretty easy and reliable. If you have to take them apart it means you are removing the wings and reworking a couple dozen little wires that will pale in comparison to the rest of the job.
 
Do we need a removable connection for the wing wiring? If you need to terminate them at the root solder sleeves or high quality butt splices are pretty easy and reliable. If you have to take them apart it means you are removing the wings and reworking a couple dozen little wires that will pale in comparison to the rest of the job.
I don't have space to attach the wings and leave them on before I haul everything to the airport. I wanted to be able to finish as much wiring as possible at home and not have to pull wire down the road. That's the only reason I'm using a connection point. I thought about using butt splices or solder sleeves. I can't say that I had any strong rationale for choosing terminal blocks over them - I just had a few spare blocks sitting around and figured they would work fine.
 
I put terminal blocks in place for my connection between the wing and fuselage wiring. Do I need to use Loctite on these screws? The terminals seemed like a very straight forward solution to making the connection from the wings, but if I'm wrong and it's a terrible idea, I'm all ears.

View attachment 75701

Did you use epoxy to attached the terminal blocks to the skin? Just curious b/c I'm thinking of doing the same thing.
 
As long as there's a lock washer under the screw heads I don't see why you would need lock-tite. Industry wide there are jillions of switches and breakers that have ring terminals screwed down that way.

I personally wouldn't do this for something like can bus wiring but that's a different topic and just my opinion.
 
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Do we need a removable connection for the wing wiring? If you need to terminate them at the root solder sleeves or high quality butt splices are pretty easy and reliable. If you have to take them apart it means you are removing the wings and reworking a couple dozen little wires that will pale in comparison to the rest of the job.
Spade connectors are quicker and make a superior mechanical and conductive connection.
 
Lock washers under the screw heads should be ok.

I really like terminal blocks when there are multiple things that connect to the same source. Like for example, an avionics bus that is powered from a switch and breaker, and you want to connect several avionics boxes to it. You can get ready-made jumpers to tie several terminals together, and then the opposing terminals all have the same power source. Much better than putting multiple wires together with a crimp, or multiple eye lugs on a threaded post.
 
Spade connectors are quicker and make a superior mechanical and conductive connection.
I’ve used lots of these terminal blocks in my wiring setup over the years with no problems. However, putting that small screw and lock washer through a ring terminal in a difficult to reach area can be a challenge. Then I discovered these (below). Make sure you connect the spade ‘Wing’ with lock washers to the terminal block (before installing the terminal block where you want it.

 
As long as there's a lock washer under the screw heads I don't see why you would need lock-tite. Industry wide there are jillions of switches and breakers that have ring terminals screwed down that way.

I personally wouldn't do this for something like can bus wiring but that's a different topic and just my opinion.
I agree, terminal blocks are fine for lights and misc stuff, stick switches etc. but never for 'signal' or low-level stuff though.
Of course, nothing is better than none.
 
I agree, terminal blocks are fine for lights and misc stuff, stick switches etc. but never for 'signal' or low-level stuff though.
Of course, nothing is better than none.
Can you elaborate for me just so I understand the rationale of why they may not be okay for signal wires (ex: using it for ALL wiring coming from the wings, which would include the autopilot servo). If it's that bad, I could pull those wires from the terminal block and just throw on a dsub connector for the AP.
 
Can you elaborate for me just so I understand the rationale of why they may not be okay for signal wires (ex: using it for ALL wiring coming from the wings, which would include the autopilot servo). If it's that bad, I could pull those wires from the terminal block and just throw on a dsub connector for the AP.
Because even small amounts of resistance from connections can cause problems
 
Signal wires are typically low voltage 0-5 V and a shield may be required so that the signal is not disturbed from the magnetic field from power wiring.
This would apply to magnetometer, oil pressure sensor, fuel tank sensor and similar wires.

Good luck
 
Im pretty sure the discontinuity caused by the addition of the terminal block and the ohmic loss of the screw connectors on a typical 500 kbps serial buss would be negligible. Same for the 0-5 v analog signals.
 
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Im pretty sure the discontinuity caused by the addition of the terminal block and the ohmic loss of the screw connectors on a typical 500 kbps serial buss would be negligible. Same for the 0-5 v analog signals.
That may be the case on a new aircraft. However the practice would be considered unprofessional. You don't see this on a certified aircraft.
And there is a good reason for it.

Good luck
 
The contact surface on an eye to washer is huge compared to a spade connection.

The spade connection actually scratches into the face of the spade. The eye connection with a screw will not produce the contact force that the spade will. And will leave a surface that is subject to corrosion and increased resistance.
 
The contact surface on an eye to washer is huge compared to a spade connection.

The spade connection actually scratches into the face of the spade. The eye connection with a screw will not produce the contact force that the spade will. And will leave a surface that is subject to corrosion and increased resistance.
I have seen MANY spade connectors that had corrosion, and the contact force from a terminal connection can easily exceed that of a traditional spade connection.
 
The only use I see for terminal blocks is common ground. I also use the heat shrink crimp connectors. Not only do they crimp but also shrink and glue themselves to the wire. Star locker where applicable ensures no loose connections.
 
Thanks for all the input! Sounds like many of the wires are probably fine in a terminal block, but there's reasonable concern when it comes to the data wires. Since I already have the blocks in place, I think I'll go ahead and just use them for the power/gnd wires, but I'll pull the signal wires off and connect those differently.
 
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I was going to use terminal strips for FWF sensors, but was suprised how heavy they were compared to other connectors.
I used D-subs.
Some connections are blade type but very few.
 
I put terminal blocks in place for my connection between the wing and fuselage wiring. Do I need to use Loctite on these screws? The terminals seemed like a very straight forward solution to making the connection from the wings, but if I'm wrong and it's a terrible idea, I'm all ears.

View attachment 75701
There're lots of good comments and discussion above and the only additional thought is to ensure that there are drain holes in the belly at appropriate locations and also to seal the seam within the wing root area where the fuselage sides and belly skin meet up. Water can otherwise leak in past the wing root fairings and run into the cockpit floor and the terminal block should naturally be kept dry.
 
I'd suggest using ring terminals instead of forks. Dune buggy folks learned this lesson with forks slipping off of a loose screw and stranding them in the dunes for lack of a screwdriver lol.
 
High quality fast on (spade) connectors are also a fine choice. They've been used forever on airplane applications with great success. As usual, just don't go cheap on the supplier :)

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I'd suggest using ring terminals instead of forks. Dune buggy folks learned this lesson with forks slipping off of a loose screw and stranding them in the dunes for lack of a screwdriver lol.
I have kind of debated this with myself. On the one hand it is nice for a wire not to flop around. On the other hand I like things to fail in an clearly obvious fashion. A loose screw on a ring terminal could be hard to find. Sometimes the circuit works, sometimes it doesn't. With a fork style terminal when it falls out it will be obvious. I still haven't decided which is better.
 
I have kind of debated this with myself. On the one hand it is nice for a wire not to flop around. On the other hand I like things to fail in an clearly obvious fashion. A loose screw on a ring terminal could be hard to find. Sometimes the circuit works, sometimes it doesn't. With a fork style terminal when it falls out it will be obvious. I still haven't decided which is better.
Agree 100% with the pain and frustration of trying to troubleshoot intermittent electrical problems. I blame most of my alcoholism on it! :p However sparks from an important wire shorting, or contacting another important wire, especially when electronics are involved can be a very bad thing. There are many relatively recent vehicle and utv recalls related to wires and fires.
 
I used a terminal block to terminate wing wiring. It’s secured to the belly skin with countersunk #8 screws. I would check the torque on the terminal screws at inspection time.

Don Broussard
RV9 Rebuild in Progress (Paint Prepping)
57 Pacer
 

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