mains electrical supply connectors crimping

Hello all I'd appreciate fine detail on crimp connectors for "mains" electrics in a home.

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When I was doing industrial wiring the proper crimping tools were provided, and they worked well. At home I won't spend $200 apiece on them so I bought used ones from flea markets and less satisfactory general purpose tools like this:

The calibration test for my good used AMP crimper is to measure the closed jaw gap with drill bit shanks. It was worn and I had to shim it.

In my experience the inexpensive commercial tools for up to 25-30A crimp connectors are usually satisfactory, I have to experiment to get adequate results from low cost tools on connectors in the 50A and above range. The pull test is standard and easy to do with a fishing scale, I also measure the resistance with a microOhm meter and look for numbers comparable to the wire resistance, my first PP120 screw connector mod measured 0.68 milliOhms.

pull test values are on page 54. Detailed operating instructions come with the crimping tool.

Thermal imagers have come down in price and are very useful for finding hot spots in live circuits caused by bad connections. Yesterday I found a 30A fuse that was overheating at 13A and replaced it with a better name brand one that runs cool.

If you solder a crimped connector, apply it at the exposed end of the wire and don't use enough to wick all the way through, the wires need to be able to flex individually where they come out. You shouldn't need to if you have the proper tool. I make do with what I have and then measure the result.

Wow! Even this "cheap" tool looks formidable.

Pull-out test: I'm talking about - one end of the cable in a vice, put a vice-grip / locking-pliers on the cable and welt the locking-pliers with a copper mallet until the cable is a mess but the crimp hasn't let-go. Much more force than this polite requirement.

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For most applications that kind of pull-out isn't necessary and maybe not even desirable...

Years ago we lost a large spruce tree during a storm. When it came down it pulled the Power Companies crimp connections apart where they connected to the house wires at the weather head/mast. So all I had to do was cut-off what was left of the crimp and use Split-Bolts to reattach them. Viola! I had power in the house again. Had those crimps held it would have pulled the mast down and/or tore part of my roof out.

IMO you only get a perfect crimp connection with crimps, crimper and specific wire all made to be used together. If any of those three vary it will be either too tight or loose.

Most of the failed crimps I came across while working were put on with the wrong crimp tool. Plastic tool used on bare crimp or worse the bare crimp tool used on plastic covered crimps.

Then there were the ones that stripped the wire too long or didn't bother to strip it and crimped on the wire insulation...

[... crimper links] [...]

As I understand it, US code for line voltage wiring requires continuous runs without connectors when a wire run is concealed; any connection must be accessible. If that's not a UK requirement, US experience with crimped butt splices for mains power wire hidden away in house walls might be irrelevant, unsanctioned, or nonexistent. That aside, I imagine many of us have used butt splices for automotive etc low voltage wiring, or for motor wiring, and your comments on the splice strength depending on the crimp point are useful and welcome.

Thanks for comment. This is Earthing (Grounding) cable under floorboards - best if it stays together and then some...

Pull-out test: I'm talking about - one end of the cable in a vice, put a vice-grip / locking-pliers on the cable and welt the locking-pliers with a copper mallet until the cable is a mess but the crimp hasn't let-go. Much more force than this polite requirement.

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That test to destruction will prove your equipment and methods but isn't for checking each connection before installing it. The 'polite' pull test checks for crimps that didn't pressure-weld together. The wire should have a nearby strain relief clamp that protects the connection from being pulled apart during further installation or remodeling.

[... crimper links] [...]

As I understand it, US code for line voltage wiring requires continuous runs without connectors when a wire run is concealed; any connection must be accessible.

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In the amateur radio requirements for lightning grounds this is the acceptable copper splice:

Although this strongly recommends against gas welding it suggests that it is still allowed to join copper grounds: You may be heading toward a situation where only illegal immigrants can perform dangerous tasks, like yours.

Yes. But testing your process and finding out its characteristics, hopefully finding a robust operating mode which gives results somewhere up near ideal and/or certainly way beyond any reasonable acceptable threshold is the number-one in any manufacturing situation, surely?

Coming from my unusual background and finding my own way, I have been amazed who people make things difficult and expensive for themselves and everyone looking at just creeping over the line with requirements. No dynamic thought about how the processes run and no thought of variables interaction. Where it would be a lot lot lot cheaper to look-at and consider the process(es), do rough-and-ready tests looking for amongst good guesses what gives good results - hopefully find one or more so close up to ideal and so broad in its stability range that the production run becomes low-cost.

People get mesmerised by the minimum acceptance criterion/criteria, to the exclusion of all other. Sign of a "service economy / managerial / post-industrial world" ?

Another very interesting whole new view of how things can be done.

Yes. But testing your process and finding out its characteristics, hopefully finding a robust operating mode which gives results somewhere up near ideal and/or certainly way beyond any reasonable acceptable threshold is the number-one in any manufacturing situation, surely?

Coming from my unusual background and finding my own way, I have been amazed who people make things difficult and expensive for themselves and everyone looking at just creeping over the line with requirements. No dynamic thought about how the processes run and no thought of variables interaction. Where it would be a lot lot lot cheaper to look-at and consider the process(es), do rough-and-ready tests looking for amongst good guesses what gives good results - hopefully find one or more so close up to ideal and so broad in its stability range that the production run becomes low-cost.

People get mesmerised by the minimum acceptance criterion/criteria, to the exclusion of all other. Sign of a "service economy / managerial / post-industrial world" ?

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I do what you suggest, and have the equipment to measure the results. It isn't common and may be expensive so I don't usually mention the procedures or necessary test gear here.

Contact and crimp resistance:

voltage drop with 1.00A flowing through the connection is also a good measure, then 1mV = 1milliOhm.

Insulation resistance:

's also useful to test old electrical appliances. I've had to disassemble and clean a few to make them safe again.

Overheating:

bought it to check the house insulation and found many other uses. It found hot and cold areas I had missed with an IR thermometer, and inner areas of a roasted chicken that weren't yet done.

Pull force:

's to proof test my home made hoisting equipment and check loads that might overstress it, mainly heavy logs and boulders. It also tests fiber and wire rope splice strength. This type failed: Applying the pull: 's much handier than a chainfall for horizontal pulls, though I think those are better and safer for vertical hoisting because you can lift higher and stand further away. My Harbor Freight 1300# electric hoist doesn't allow fine position control and starts with a considerable jolt that flexes the supporting beam.

Those may not be the model I own or price I paid, often second-hand and overdue for calibration. I've been experimenting with the consequences of avoiding fossil fuel by using solar electricity and found several problems in available equipment with my test gear.

Personally I want to be satisfied with my workmanship but commercially there was no reward for doing better than required if it took longer and cost more, which was typically the case once you learned to work efficiently. The requirements were supposed to be matched to the specs of available products, and generally were for US manufacturers. I don't see that with imports and test before using.

People get mesmerised by the minimum acceptance criterion/criteria, to the exclusion of all other. Sign of a "service economy / managerial / post-industrial world" ?

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I've come to believe that acceptance criteria can be valid if written by people with both theoretical and practical knowledge, but they may prefer to avoid working in a bureaucracy, leaving neurotic paper-pushing staffers with literary degrees to formulate them from incomplete written sources. Mitre was an attempt to isolate scientists and engineers working on government projects from its bureaucracy. Yesterday a very hands-on and disgusted municipal employee and I were discussing how the bureaucracy is a welfare refuge for managers whose emotional dysfunction keeps them from working commercially.

Like you my combination of knowledge and practical skills provokes envy and resentment from those who consider themselves inherently superior because it feels good, like the aristos of the Ancien Regime and today's leftists.

Much of the Internet ad copy for high tech products and new developments appears to come from writers who don't comprehend the subject beyond quoting what they think they were told, and may lack the practical ability to change a light bulb or tie their shoelaces. Look at the insulting comments on the writer's incompetence that follow Yahoo high tech articles. I have experience here, I've struggled to teach actors how to build scenery and intelligent Mensans how to paddle a canoe. Hardly any could learn to tie a bowline. The actors felt such work was beneath them when really it was beyond them.

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I had not seen those before. Makes for a nice end without all the sharp areas like U-Bolts do. Too bad it doesn't hold up well...

It reminds me of the electric connector I liked to use for a triplex service hook-up:

Allows aluminum to copper connections and is easy to tighten up. Sucks to tape up but can't have every thing😉

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Well said👍

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I had not seen those before. Makes for a nice end without all the sharp areas like U-Bolts do. Too bad it doesn't hold up well...

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IIRC it slipped at around 100#. I had tightened it by hand in the woods, it might grip better if tightened with an impact driver, or a cap screw substituted. They could be useful to drag an eye splice over a high branch or minimize the fumbling of installing Crosby clamps and thimbles.

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It's stored in my head now. For some unknown reason I remember stuff like that for a long time. Neighbor's name down the street is a different story🙄

Could be useful, keeping in mind that it may not be a "strong" connection... Thanks!

I am very lucky to live among people (our little community down here in The Holler) who appreciate and utilize my talents rather than being intimidated by them . Of course , every one of them has areas where they shine , and I appreciate that too .