Crimping - Best Practice ?

[Maine Sail]

Originally Posted by Dockhead

So do I need to buy another one of these expensive things for butt splices?! It doesn't look like the better K-frame tool even has dies for butt splices; they want you to buy the lighter duty RS type for that.

I sacrificed one of the Molex butt splices in an experiment. I crimped it once, then flipped it around and crimped it in the opposite direction. Looks damned good to me. Is that an acceptable practice, or do I need to buy another tool for butt splices? What say ye?

If you don't have a tool that allows the "strain relief" side to be opened independently, to allow for crimping butts, then flipping it around so the strain relief crimps the polyolefin or nylon only, can work. Be sure to "load test" the terminals to make certain your tool is properly sized for the terminal. Also always make sure you are not confusing the strain relief side with the crimp band side of the tool. Making the crimp with the part of the die intended for strain relief is unsafe.

Personally I would use UL486A standards as a bare minimum crimp pull strain to shoot for with your tool/terminals.

I personally prefer to see them meet US Mil-Spec Mil-T-7928 standards as my tools do, and exceed.

UL486A Crimp Pull Test
14GA = 50 Pounds
12GA = 70 Pounds
10GA = 80 Pounds
8GA = 90 Pounds

Mil-T-7928
16GA = 50 Pounds
14GA = 70 Pounds
12GA = 110 Pounds
10GA = 150 Pounds
8GA = 225 Pounds

[nigel1]

Originally Posted by Dockhead

Well, I guess I could put in spade connectors everywhere instead of butt splices.

But I do have different cases where I have wires coming out of some device (electric toilet, bilge pump, etc., etc.) which need to be connected to another wire. That's where I typically use butt splices, not to save wire.

Just out of interest, why use butt connectors for pumps etc.
Fitted mine with waterproof plugs sockets to allow easy removal.

[Lake-Effect]

Originally Posted by nigel1

Just out of interest, why use butt connectors for pumps etc.

Fitted mine with waterproof plugs sockets to allow easy removal.

Every connection is a potential point of failure. A splice can fail open (ONE failure mode); a plug can also fail open AND could be knocked/pulled apart AND could accidentally be left unplugged after service (THREE failure modes). Wait, a plug can short internally too. So that's FOUR modes.

So it's a question of utility vs reliability.

If you use a good plug/socket, and are conscientious about making sure it's always connected and tested, a plug/socket would be fine.

If you are, for example, relying on your bilge pump to keep an unattended boat from sinking, and it's not something you need to connect/disconnect frequently, then you might opt to keep points of failure to an absolute minimum... in which case a splice would be preferable to a plug/socket.

All the above assumes suitable materials and good workmanship, of course.

My 2 cents.

[nigel1]

Thanks for the logical explanation, I've been using something like this:

[Andrew Troup]

Does anyone use bootlace ferrules for boat wiring, in cases where the terminal block is made to accept the stripped end of a piece of wire?

I like them for on-land wiring into terminals of this type, as I hate the way a few more copper strands tend to break off every time you remake a connection to a bare wire end, but I don't like the way water can wick into the wire behind the bellmouth of the ferrule in marine situations.

I don't know the correct name, but there is a fully sealed wire end termination which is a tinned copper seamless tube which is capped at the outboard end to stop water getting in the end, and which has an adhesive-lined heatshrink sleeve integrated at the inboard end.

The only ones I have seen require to be crimped through the inboard sleeve.

I prefer the idea of crimping the bare 'seamless tube' end onto the wire, in the same region where it will be clamped in the terminal block, like a bootlace ferrule.

This seems to me likely to be more secure, and puts the plastic sealing sleeve at less risk of leaking.

Has anyone seen such a fitting?

[Outwest34au]

Originally Posted by Andrew Troup

Has anyone seen such a fitting?

Google up heatshrink crimp terminals, try images too. Then find who is nearest you.

I have also used terminals that have a solder (sodder) band inside that are heated with a lighter and solder and shrink wrap at the same time. Pretty cool, I think they came from an airport workshop somewhere.

[Outwest34au]

Originally Posted by nigel1

Thanks for the logical explanation, I've been using something like this:

Good choice.
I am also a big fan of the Deutsch plugs. I prefer the pins to be the one piece hollow barrel crimp type tho, just because I have the tool that does the job on them.

[goboatingnow]

Superseal is AMP

[Rapanui]

I use tinned copper wire, adhesive lined heat shrink crimp terminals and a ratchet crimp tool. The majority advice I have seen is not to solder connecting wire as that will embrittle the joint. On patrol boats and other warships, we used crimps, and either Hellerman or heat shrink sleeves and never soldered

[The Garbone]

Originally Posted by Rapanui

I use tinned copper wire, adhesive lined heat shrink crimp terminals and a ratchet crimp tool. The majority advice I have seen is not to solder connecting wire as that will embrittle the joint. On patrol boats and other warships, we used crimps, and either Hellerman or heat shrink sleeves and never soldered

+1 on this except my crimper is non ratcheting. I know the feel of a good crimp (after a lot of trial and error), a ratcheting tool would have saved me some headaches over time though.

[Boracay]

Lacking fancy equipment and parts and not trusting crimps if I have to join two wires together I slide heat shrink over one wire, twist the wires together, fill the lot with solder, coat with liquid electrical tape and then slide the heat shrink over the top and shrink it down till the liquid electrical tape oozes out of both ends.

I know it's not considered best practice, but the idea having a crimped connection made up of dissimilar metals where salt water can get in fills me with dread.

My opinion is that crimped connections should only be used where water would normally never get into the joint.

[goboatingnow]

Originally Posted by Boracay

Lacking fancy equipment and parts and not trusting crimps if I have to join two wires together I slide heat shrink over one wire, twist the wires together, fill the lot with solder, coat with liquid electrical tape and then slide the heat shrink over the top and shrink it down till the liquid electrical tape oozes out of both ends.

I know it's not considered best practice, but the idea having a crimped connection made up of dissimilar metals where salt water can get in fills me with dread.

My opinion is that crimped connections should only be used where water would normally never get into the joint.

A good crimp is gas tight.

Dave

[Lake-Effect]

Originally Posted by Boracay

Lacking fancy equipment and parts and not trusting crimps if I have to join two wires together I slide heat shrink over one wire, twist the wires together, fill the lot with solder, coat with liquid electrical tape and then slide the heat shrink over the top and shrink it down till the liquid electrical tape oozes out of both ends.

I know it's not considered best practice, but the idea having a crimped connection made up of dissimilar metals where salt water can get in fills me with dread.

My opinion is that crimped connections should only be used where water would normally never get into the joint.

The problem with soldered splices is embrittlement at the joint as already mentioned, and also that in the event of an overload, if the hottest point is the soldered connection or close to it, the solder could melt and the joint will quickly fail.

The ABYC's position is that soldering a wiring connection is only acceptable if the connection is first made mechanically sound. A running splice in stranded wire is not considered by them to be sufficiently strong. So, since a good crimp is both mechanically and electrically sufficient, it doesn't seem productive to also solder it.

Tinned wire in a plated crimp connector is fairly resistant to corrosion, compared to un-tinned. A crimped connection can be sealed in a number of ways with heatshrink, sealants or greases. And, of course one should take care to avoid placing splices in wet or exposed locations.

I've successfully used non-ratcheting crimpers, but a properly adjusted set of ratcheting crimpers are confidence-inspiring, to the novice using it as well as the next person who can tell by the crimp pattern that a better tool was used. I have found knock-off ratcheting crimpers that do a good job for as low as US$ 30

(That superseal connector looks to be well-made and weather-resistant. I wouldn't be afraid to use it, if its current rating met or exceeded the circuit's fuse or breaker rating)

[Dockhead]

Originally Posted by Lake-Effect

The problem with soldered splices is embrittlement at the joint as already mentioned, and also that in the event of an overload, if the hottest point is the soldered connection or close to it, the solder could melt and the joint will quickly fail.

The ABYC's position is that soldering a wiring connection is only acceptable if the connection is first made mechanically sound. A running splice in stranded wire is not considered by them to be sufficiently strong. So, since a good crimp is both mechanically and electrically sufficient, it doesn't seem productive to also solder it.

Tinned wire in a plated crimp connector is fairly resistant to corrosion, compared to un-tinned. A crimped connection can be sealed in a number of ways with heatshrink, sealants or greases. And, of course one should take care to avoid placing splices in wet or exposed locations.

I've successfully used non-ratcheting crimpers, but a properly adjusted set of ratcheting crimpers are confidence-inspiring, to the novice using it as well as the next person who can tell by the crimp pattern that a better tool was used. I have found knock-off ratcheting crimpers that do a good job for as low as US$ 30

(That superseal connector looks to be well-made and weather-resistant. I wouldn't be afraid to use it, if its current rating met or exceeded the circuit's fuse or breaker rating)

When I was a boy, I didn't trust crimp connections, either, and when entirely rewiring an old MGA, I soldered every wire to the crimp connector, thinking I was taking extra time to do great work.

Within a few months nearly every connection had failed -- the wire soaked in solder above the connection became extremely brittle and simply broke off with the vibrations (which MG's are good at creating, admittedly!).

After that I decided not to invent my own "best practice", but to learn from people who understand it more. It was a really good lesson. I think the standards for aircraft wiring are good enough for my boat. They don't use a drop of solder.