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From: Joe Gwinn <joegwinn@comcast.net>
Newsgroups: sci.electronics.design
Subject: Re: electrical deaths
Date: Mon, 02 Dec 2024 18:20:44 -0500
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On Mon, 2 Dec 2024 13:40:13 -0800, Joerg <news@analogconsultants.com>
wrote:

>On 12/2/24 1:17 PM, Joe Gwinn wrote:
>> On Mon, 2 Dec 2024 11:35:41 -0800, Joerg <news@analogconsultants.com>
>> wrote:
>> 
>>> On 12/1/24 9:59 AM, Joe Gwinn wrote:
>>>> On Sat, 30 Nov 2024 14:24:11 -0800, Joerg <news@analogconsultants.com>
>>>> wrote:
>>>>
>>>>> On 11/26/24 6:53 PM, john larkin wrote:
>>>>>> https://www.researchgate.net/figure/Age-adjusted-mortality-rates-from-electrical-injuries-per-1-million-population-European_fig1_221916189
>>>>>>
>>>>>> The US (0.63 PPM) is probably low partly because we have mostly 120
>>>>>> volt gadgets. I usually wire boxes hot, and get tickled now and then,
>>>>>> no big deal.
>>>>>>
>>>>>> Some countries are astounding.
>>>>>>
>>>>>
>>>>> Twice the line voltage makes a difference. Also, some countries such as
>>>>> Germany have non-polarized wall outlets which was a clear mistake on the
>>>>> part of the standards guys. Think toasters and forks.
>>>>
>>>> We have polarized line plugs in the US, but the wiring old and new
>>>> isn't consistent, or becomes so over time.  And so people often
>>>> intentionally defeat the polarization.
>>>>
>>>> Part of the problem is that for many small appliances, the plug was
>>>> bigger than the appliance.  Probably more expensive too.
>>>>
>>>> Anyway, my instinct is that not polarizing plugs and sockets is more
>>>> realistic, as it forces manufacturers to pass safety regardless of hoe
>>>> things are plugged in.
>>>>
>>>
>>> Polarization can save the day with toasters and similar appliances. Then
>>> you can make sure that neutral comes in at the top end of the meanders.
>>> In the US, 99+ percent of cases will not have line and neutral reversed.
>> 
>> I think that the 99+ percent is quite optimistic, especially on older
>> buildings.  Back when I was an apartment-dweller, ran into all manner
>> of trouble, to the point that one of the first things I did in a new
>> apartment, was to turn the power off and opened all electric boxes,
>> and straighten out the "carpenter wiring", much of this being
>> dangerous.
>> 
>
>Not too optimistic, I think. The home inspector we used was a seasoned 
>guy and he said outlets where line and neutral are reversed were very 
>rare. He made it a habit of testing them all.
>
>
>> War Story One:  In the 1970s in Washington, DC, my boss was having
>> considerable problems with the lights in his newish house in the
>> suburbs.  For instance, when he turned one light on, an unrelated
>> light would go off.  I said it sounded like some kind of grounding
>> problem.  Eventually he invited me to dinner in his house, and bring
>> your voltmeter.  Which I did.  It turned out that the solid copper
>> wires at every electrical device (wall switch, outlet, light, et al)
>> were loose - the electrician (or his assistant had forgotten to
>> tighten all the terminal screws down.  (Stranded wire was not used
>> then.)  So boss called the builder to have all those neglected
>> terminal screws tightened properly.  He was lucky that there wasn't a
>> fire.
>> 
>
>That's a serious blunder by a contractor. 

It certainly was, but if the house had burned down, good luck figuring
out why from inspection of the ashes.

There is an electrical inspector whose approval is required before the
house can be occupied, but they do not generally test that the screws
are tight.

What probably happened is that the electrician had an apprentice, and
so the electrician does the hooking up and the apprentice checks that
it's correct (and thus learns) and does the final tightening.  They
somehow got distracted, and the last step never happened.


>   In Germany we had mandatory 
>road-worthiness checks for cars every two years. I think they still do. 
>The inspector came up from underneath my dad's car with a pale face. 
>"Sir, come down here, you've got to see this". The four connector bolts 
>of a universal joint in the steering column were in there alright but 
>the mechanic had forgotten to put any of the nuts on them, let alone 
>tighten anything. They were just rattling around in their holes without 
>nuts. My dad was one of the guys who floored it on autobahns, 120mph and 
>more. That could have resulted in a horrific accident.

Good lord.  That would have killed many people.


>> War Story Two.  Ten years later, in Baltimore, MD, some friends
>> complained that their kitchen light (in the center of the ceiling)
>> flickered, and mentioned that when they used the sink in the washroom
>> off the kitchen, sparks fell from underneath that sink.  I didn't
>> believe them at first, but they persisted.  It turned out that the
>> building (which was quite old) still had some old knob-and-tube
>> wiring.  The plumbers had recently replaced the drain pipe from the
>> bathroom above the washroom with a new copper pipe, and had barged
>> through the existing knob-and-tube wiring, breaking the return path,
>> but accidentally making the drain pipe live.  The current made it from
>> the copper drain pipe to the existing cast iron drain through the
>> hardware on the washroom sink.  Stopgap was to firmly ground the drain
>> pipe.  I assume the owner of the building had words with the plumber,
>> and got an electrician.  Anyway, nobody was hurt, and nothing burnt
>> down.
>> 
>> I have many such stories, but this will do for now.
>> 
>> And I bet that Europe also has its heart-stopping stories.
>> 
>
>Over there it's often willful neglect. I sat at a pcinic table of a 
>campground in Italy, having some wine with the owner. The lights 
>flickered and a loud phzzzzt was heard, sparks flew. The overhead cable 
>to the freezer at the (very far away) end of that line was arcing. "I 
>think we should turn this off and run an extension cord" ... "Nah, 
>happens a lot, it'll hang on for a while. I'll fix this tomorrow. Or the 
>day after".

Yes, very often exactly that.  I have similar stories.


>> 
>> PS:  I do prefer the Euro-style closed terminals that work for
>> stranded and solid wire.  They are allowed in the US, but not all that
>> common outside of industrial sites.  One big advantage is that they
>> take far less volume than wire-nuts and the like.
>> 
>
>Yes but unfortunately most of them contain just a screw and not a 
>pressure plate. You are supposed to use ferrules on stranded wire but 
>hardly anyone does.

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