Stranded or solid?

[DeltaVee]

So when wiring up an electronics bay, is there any consensus as to whether the wiring should be of the stranded or non-stranded variety? My first, working-reasonably-well electronics bay uses stranded wire from battery to altimeter, but for the channel to the main deployment charge well, I used solid copper wiring that I had available. That wire is well secured (glued) to the sled and is not under any undue stresses even when I remove the sled from the coupler.

The stranded wiring I used has the ends tinned so that I won't get any loose fragments getting into the electronics... which of course wouldn't be an issue with non-stranded wire. The HPR safety code doesn't seem to go into this detail.

If this is like asking about epoxies, just forget I asked!

 

[Art Upton]

Wire Thread

 

[DeltaVee]

Wire Thread

I meant what I said in closing!

 

[Art Upton]

Solid wire is used on lots of e-matches. I always brought my wires from the match right to the altimeter via small holes in the bulkhead that I would seal with silicone sealer for the flight. It peals back off after use. Others use terminal blocks. I considered them a point of failure later as they get dirty.

For the wires for Altimeter battery power I used stranded, as it flexes over time without breaking like solid wire does , with an exception. When you 'tin' the wire, it is now solid so if you take the tined wire out of contacts and put it back in a lot, it will crack just like a solid wire would over time.

 

[DeltaVee]

For the wires for Altimeter power I used stranded, as it flexes over time without breaking like solid wire does , with an exception. When you 'tin' the wire, it is now solid so if you take the tined wire out of contacts and put it back in a lot, it will crack just like a solid wire would over time.

Fortunately not in the habit of doing this, but point well taken.

 

[Art Upton]

Fortunately not in the habit of doing this, but point well taken.

There will be lots of other's opinions, all valid, that will come to this thread. Chose what you feel comfortable with.

 

[cerving]

If it needs to flex/move, use stranded. If it's going there once and being tied down, solid is fine.

For terminal blocks, ideally you'd use either stranded wire with ferrules, or you'd use solid wire and solder it to stranded if required. You CAN use tinned stranded wire with terminal blocks... but they're going to flatten as you screw them down, so you need to make sure they're tight before every flight. Of course, if you're using terminal blocks at all in your AV bay you should be checking every connection before every flight anyway... which is my #1 argument against not opening up AV bays between flights. A continuity check isn't going to show you a loose wire.

 

[Art Upton]

Fortunately not in the habit of doing this, but point well taken.

Now that I am thinking more, I never tined my Stranded wires because of that issue, that vibration over time might crack them. I've seen tined wires in ham Radio shacks break just by moving radios about on the other end of the power wire.

 

[DeltaVee]

I have stranded wire soldered to my EggTimer mini-switch, for both input power and output to the StratoLoggger altimeter, the inputs of which are tinned. That said, this connection is never messed with... but I have to solder the power input/output to the mini-switch which effectively tins the wire.

 

[Rocketjunkie]

I use new wires for everything in the alt-bay so I just use the ematch wires. Any wires for multiple flights would be stranded as it's less likely to break. Battery to altimeter is the standard 9V snap connector that has stranded wires. This is the only wire that gets reused.

 

[jderimig]

Stranded with ferrules or crimped terminations.

 

[DeltaVee]

If it needs to flex/move, use stranded. If it's going there once and being tied down, solid is fine.

For terminal blocks, ideally you'd use either stranded wire with ferrules, or you'd use solid wire and solder it to stranded if required. You CAN use tinned stranded wire with terminal blocks... but they're going to flatten as you screw them down, so you need to make sure they're tight before every flight. Of course, if you're using terminal blocks at all in your AV bay you should be checking every connection before every flight anyway... which is my #1 argument against not opening up AV bays between flights. A continuity check isn't going to show you a loose wire.

@cerving So regarding soldering/tinning. Would there be a better method of attaching the wiring for the eggtimer quantum, mini switch etc than direct soldering? Bolt down tiny tiny ferrules for example?

My currently used miniswitch has soldered connections, but the wiring sheath is very, very stiff... hopefully mitigating some of the issue (maybe?)

 

[3stoogesrocketry]

Single strand is nice if there will never be any vibrations or moment in the wires. Braided for all contact points that move or are more then 1 use.

 

[DeltaVee]

First off, thanks to all who offered an opinion. My takeaway is that one should check the wiring often regardless of which type is used. That said, I think there's enough info here for me to do what I have in mind safely.

 

[FredA]

Of course, if you're using terminal blocks at all in your AV bay you should be checking every connection before every flight anyway... which is my #1 argument against not opening up AV bays between flights.

use new wires for everything in the alt-ba

Remove the terminal blocks and solder to the electronics.
Terminal blocks are always through-hole, so soldering wires in their place is super easy.
Use stranded where possible.
Immobilize wires with duct tape.

And color-code your wires.

 

[Rocketjunkie]

Remove the terminal blocks and solder to the electronics.
Terminal blocks are always through-hole, so soldering wires in their place is super easy.
Use stranded where possible.
Immobilize wires with duct tape.

And color-code your wires.

No. I run the ematch wires through holes in the bulkheads directly to the altimeter so I use the terminal blocks. I do pull the wires to make sure they are clamped. New wires from new ematches for every flight. Soldering to the electronics means the terminal blocks are somewhere else such as the av-bay bulkhead. There are as many ways of wiring altimeters as rocketeers that use them

 

[cerving]

@cerving So regarding soldering/tinning. Would there be a better method of attaching the wiring for the eggtimer quantum, mini switch etc than direct soldering? Bolt down tiny tiny ferrules for example?

My currently used miniswitch has soldered connections, but the wiring sheath is very, very stiff... hopefully mitigating some of the issue (maybe?)

Answering your question, plus some additional hints...

In order of preference, assuming that this is only for termination to terminal blocks, and any wire that can move is tied down:

Solid wire (but NOT for wires that can move!)
Stranded wire with ferrules (although ferrules can be a problem for the 2.54mm-pitch blocks)
Stranded wire, tinned

Regardless of which you use, check every terminal block before every flight. Yes, you will have to open up the AV bay to do this.

If you're soldering directly to the boards, used stranded wire, and tie down your wires to the sled (see a common pattern here?)

24-gauge stranded network cable works great... if you can, use plenum-rated wire, it has a Teflon jacket and is more durable and heat-resistant (but is also stiffer)

For any wire that exits the bulkplates into the "hot" areas, inspect them after every flight and replace as necessary.

If you're using terminal blocks on the outside of the bulkplates (in the "hot" areas), cover them with masking tape before every flight so they don't get nasty and corroded. That goes for "twist and tape" connections, too.

 

[techrat]

Stranded will take vibration and hard knocks better. Solid wires tend to snap/break over time.
So, the answer is BOTH. Use solid wires for things that are used ONCE and then disposed of (like ignitors/ematches)
Use stranded for wiring that you think will get re-used.

 

[jderimig]

Solid wire is actually pretty strong, the biggest problem is stripping the insulation and putting a nick in the wire which will be the failure point very quickly.

Use caution when using stranding wire in the screw terminal block. That is against most industrial standards and code. The reason is a screw down terminal block electrical connection depends on the elasticity of the wire to provide a constant force in the connection. Stranded wire will over time relieve the force as the strands move under the force of the screw. Tinning the stranded wire in a terminal block is worse. Lead is not elastic and will yield under the screw force over time, and the tinning will cause a stress concentration where the untinned strands meet the tinned strands.

 

[DeltaVee]

Answering your question, plus some additional hints...

In order of preference, assuming that this is only for termination to terminal blocks, and any wire that can move is tied down:

Solid wire (but NOT for wires that can move!)
Stranded wire with ferrules (although ferrules can be a problem for the 2.54mm-pitch blocks)
Stranded wire, tinned

Regardless of which you use, check every terminal block before every flight. Yes, you will have to open up the AV bay to do this.

If you're soldering directly to the boards, used stranded wire, and tie down your wires to the sled (see a common pattern here?)

24-gauge stranded network cable works great... if you can, use plenum-rated wire, it has a Teflon jacket and is more durable and heat-resistant (but is also stiffer)

For any wire that exits the bulkplates into the "hot" areas, inspect them after every flight and replace as necessary.

If you're using terminal blocks on the outside of the bulkplates (in the "hot" areas), cover them with masking tape before every flight so they don't get nasty and corroded. That goes for "twist and tape" connections, too.

Thanks Cris! This sums it all up very nicely. For the "hot zone", I'm partial to Doghouse Rocketry charge wells (more specifically the "ejection charge mount kit). I find the self-contained nature of them to be very convenient, and the contacts are easy to keep clean... you just hook up the e-match and move on. Also the fitment of the posts/screws thru the bulkhead is so tight I'd almost bet they would not sealing up (depends on the drill size you use of course).

 

[SolarYellow]

Answering your question, plus some additional hints...

In order of preference, assuming that this is only for termination to terminal blocks, and any wire that can move is tied down:

Solid wire (but NOT for wires that can move!)
Stranded wire with ferrules (although ferrules can be a problem for the 2.54mm-pitch blocks)
Stranded wire, tinned
...

24-gauge stranded network cable works great... if you can, use plenum-rated wire, it has a Teflon jacket and is more durable and heat-resistant (but is also stiffer)

Ferrules are also available without the plastic insulators, much like other crimp terminals.

Just bought a bunch of 22 (0.5mm^2) and 24 AWG (0.34mm^2) insulated and uninsulated ferrules from AliExpress for dirt cheap. They also come in 6mm and 8mm lengths, which will work a little better with the terminal blocks on my Proton than the long ones that came in the "insulated assortment with crimper" I bought from Amazon.

 

[kramer714]

Yank It... (the wires)

I was mentoring a SLI team, they wanted to put ferrules on everything. When they started having problems I asked them to tug on it (the wires), more than half came out with a light tug. I had them as part of their assembly give each ferrule a tug after crimping. Funny thing happened, seemed like they stopped using the ferrules and just started tinning the wires// Easier than trying to get the crimping right. Having said that, high school kids not using a proper crimping tool.

 

[bad_idea]

Just bought a bunch of 22 (0.5mm^2) and 24 AWG (0.34mm^2) insulated and uninsulated ferrules from AliExpress for dirt cheap.

Link(s), please?

 

[SolarYellow]

https://www.aliexpress.us/item/3256803591391817.html

https://www.aliexpress.us/item/3256806516227646.html

 

[bad_idea]

https://www.aliexpress.us/item/3256803591391817.html

https://www.aliexpress.us/item/3256806516227646.html

Second link fails for me. Is it same seller?

 

[DeltaVee]

Ferrules are also available without the plastic insulators, much like other crimp terminals.

Just bought a bunch of 22 (0.5mm^2) and 24 AWG (0.34mm^2) insulated and uninsulated ferrules from AliExpress for dirt cheap. They also come in 6mm and 8mm lengths, which will work a little better with the terminal blocks on my Proton than the long ones that came in the "insulated assortment with crimper" I bought from Amazon.

How did you connect power to your proton? I'm using a quantum and a mini-switch/stratologger... I soldered the wiring directly to the quantum and mini-switch for power... Not clear there would be a better way.... e.g. lugs and bolts small enough.

 

[SolarYellow]

Second link fails for me. Is it same seller?

No, different sellers. The link still works for me. It's "Shop1103345356 Store".

How did you connect power to your proton? I'm using a quantum and a mini-switch/stratologger... I soldered the wiring directly to the quantum and mini-switch for power... Not clear there would be a better way.... e.g. lugs and bolts small enough.

Proton has WiFi switching built in, so I'm going to just solder a pigtail that the battery plugs directly into to the board. I paid to have it assembled and the assembler installed pigtails with the big red JST connectors, but I'm going to take those out and use connectors that work with the connectors that came on the batteries.

If it proves not sufficiently durable over a number of cycles, as some have discussed here, I'll probably switch to the Micro-Fit 3.0 for power. But I'm also planning a lot of rockets where those will be just way too darn big. It may just mean a higher level of maintenance and replacing stuff more frequently to push the systems to the edge.

 

[bad_idea]

No, different sellers. The link still works for me. It's "Shop1103345356 Store".

Working for me now too. Must have been a glitch in the Matrix.

 

[SolarYellow]

Ferrules are also available without the plastic insulators, much like other crimp terminals.

Just bought a bunch of 22 (0.5mm^2) and 24 AWG (0.34mm^2) insulated and uninsulated ferrules from AliExpress for dirt cheap. They also come in 6mm and 8mm lengths, which will work a little better with the terminal blocks on my Proton than the long ones that came in the "insulated assortment with crimper" I bought from Amazon.

These arrived and I played with stuff a bit. The 22 (0.5mm^2) ferrules, when crimped on a wire, are just too big to fit into the screw terminal block on my ET Proton. The 24 AWG (0.34mm^2) ferrules work great. The 8mm length is fine, as a good, sharp, flush cutting tool will allow them to be shortened as desired after crimping with a clean end. Insulated provides a little more strain relief, protecting the wire from flex where it is weakest, and I can get by with them with the Proton in a PNC-60. In a narrower sled, e.g. a BT-55 tube, I'd have to use the uninsulated ferrules to have an acceptable bend radius in the wire.