Re: electrical deaths

On Tue, 3 Dec 2024 19:23:41 -0800, Joerg <news@analogconsultants.com>
wrote:

On 12/3/24 9:16 AM, Joe Gwinn wrote:

On Tue, 3 Dec 2024 12:10:54 +0100, Arie de Muijnck <noreply@ademu.nl>
wrote:
 

On 2024-12-03 00:20, Joe Gwinn wrote:
>
.....

>
I don't either, because the approved euro terminal strips don't
provide plates for the smaller wire sizes.  I also use the euro
terminal strips inside appliances, and if I'm connecting finely
stranded wire, I tin the wire with 63-37 solder to consolidate it, and
clamp that.
>
Joe Gwinn

>
>
DON'T! The tin will flow slowly under pressure, and loose the connection.
It was a common habit in the Netherlands until forbidden. With a reason.

 
Yes, I know.  Only done for small wires at low power.
 

>
If it's mains stuff the arcing can still spark a fire. I've had numerous
cases where I found signal or control wires were tinned and then
clamped, and the connections failed or became erratic. Usually after
many years.

I guess the best answer is yet another war story:

For short-term lab stuff, I don't worry about such details, but with
power it's far more important to have mechanically solid connections -
no test probe and alligator-clip jumpers (like I used in my youth)
here.

When in 2019 I was figuring out the wiring of a friend's 3-phase
Dahlander two-speed 240 Vac (60 Hz) 5HP motor (that powered a Clausing
Colchester Triumph 13" lathe he was restoring), it had to be all 4mm
banana plugs and jacks. 

My friend's shop had been a commercial shop, and so had very high
current available - not quite arc flash territory, but can be
dramatic. 

The problem was that when the lathe was received the motor's wire
markers were missing, and so had to be deduced from measurements.  The
motor had six leads (only the frame is grounded) and one connects
three power wires, with or without the three shorting jumpers.  One
configuration is full speed, another is half speed, al all others are
melt-down with drama and smoke. 

Measuring winding DC resistances with probes did not work - contact
resistances too large and unstable.  Likewise capacitances and winding
inductances.

For this effort, I made a six-bar terminal strip, brass bars on a wood
base.  Each bar had a screw-terminal (for the six motor wires), and
two 4mm diameter reamed holes (for the banana plugs, power and
jumper).  The bars are 0.25" wide by 0.75" high by 2.0" long, made of
alloy C360.

Long saga, but succeeded, and the lathe has been in regular use since
then. 

For operational stuff, the solder tinning is only for low-voltage (<
50V) control wiring.  What I sometimes do is to thread the stranded
wire through some brass tube, and solder wire to the brass tube.  Or
crimp a spade or ring terminal to the wire, for use in screw-type
barrier strips.  One can also crimp the brass tubing, with the right
tool.  I've had this one for at least 40 years.

.<https://www.amazon.com/Buchanan-Insulated-Crimper-8-L/dp/B007EX5NP8>

Joe Gwinn