1.5mm cable, 90 Amps and various connectors

[ARW]

[dennis]

Is someone going to update the wiki to say that you can make good crimped connections with a cheap crimper?

[ARW]

Why don't you?

[dennis]

Too much responsibility.

[Andrew Gabriel]

What I guessed, except I didn't know if the wago or screwit would give out first.

On reflection, the wago is going to have the smallest contact area, so I perhaps could have guessed. That will have generated the excess heat which caused the wire to burn out next to it.

An interesting test would be to run it less extreme over a longer time, and include more temperature cycling.

[ARW]

I would have liked to have seen the 30A test run for a couple of hours.

There is an interesting bit at 7min 29 seconds (well I find it interesting). At the failure point there looks to be some metal from the WAGO on the LHS that seems to have no purpose.

[Dave Plowman (News)]

Also be interesting to conduct the same test on after say 20 years old. To see how well the various connectors remain a low impedance connection.

[Robin]

While that is a possible explanation I noticed that the red wire into the Wago failed where it had been bent, and where it was flexed further as he set it out. It struck me that may have led to some work hardening, causing structural imperfections (eg dislocations) which increased resistivity locally.

It might be argued that Wago connectors risk that effect more than others but that's another issue.

[dennis]

The break was a fair distance from the wago. It was probably damaged when stripping rather than the wago failing. A video with a thermal camera would likely show the real answer but I don't have one so its up to someone else. Does bigclive have a thermal camera?

[Andrew Gabriel]

Yes, I think that might cause the screwit to fail first, as it won't have a gas-tight contact area by then, so more likely to have a thick layer of copper oxide contact after years of temperature cycling.

[Dave Plowman (News)]

I've got a lot of experience of crimped connectors, and a badly made one will give trouble before a correctly made one. Some time down the line.

Of course the retail price of a tool is no true guide of anything.

[dennis]

The problem is that ratcheting crimp tools are adjustable and unless they are adjusted correctly they just make consistently bad crimps. You really need to know what a good crimp looks like and once you do you can make them with a £1.99 lidl special, with care that is.

[dennis]

I don't see how a screwit ever has a gas tight connection, or the screw terminal ones.

[F Murtz]

The fail in the wire was probably a nick in the wire from bad stripping technique and it also seemed to show that the wire nut does not deserve its bad name if used correctly.

[John Rumm]

What would you want to update?

The description in the video said it was made with a cheap *ratchet* crimper from ebay - probably not unlike the one pictured in the cable crimping article:

Even the cheaper ones usually do the job. They may not have the life expectancy of a decent one, but that probably does not matter for low volume work.

While it may be possible to make a decent crimp with one of the flat stamped metal types:

I would be less inclined to recommend them for mains work down to the poor repeatability of the crimps and the amount of judgement required to asses if the result is adequate)

[John Rumm]

Screw terminals can be gas tight at the point of contact, due to the very high clamping pressure.

A wirenut might manage to be for a while if its the type with a sharp edged helix that can cut into the wire surface.

[Mike Tomlinson]

En el artículo , ARW escribió:

You have to wonder what's in the urn behind him. His mother's ashes?

His videos are good though, I've watched a few.

In other news, Big Clive checks out a pink "massager" which might prove shocking in more than one way.

[Andrew]

Was he using an electric welder to supply the current ?.

Is this a valid test on cable and connectors that are rated to carry 230v AC ?.

[Dave Plowman (News)]

Running any cable (and or connectors) at well above its rating is really only of academic interest anyway.

[Tim Watts]

I'm not sure it tells us much when the wire itself is so hot it melts the insulation.

I would consider a test that started at 2-3 times the rate current for some hours, inching up the amps until one of the connectors failed, then the second, etc more interesting.

Nothing visible was happening at 36A - already twice what 1.5mm2 is rated for in free air. The Wago looks like a 24A device - so that did perfectly well at 36A - that gave me confidence in all the connectors (even the stupid wirenut).

72A is a bit of a step to go after that - nearly 3 times the limit on the Wago - nothing surprising that all the connectors melted along with the wire.

It was fun - but it would have been cool if he could have gone up from

36A in 5A increments...