On Friday, October 22, 2021 at 3:10:29 PM UTC-5, Terje Mathisen wrote:
> Thomas Koenig wrote:
> > Terje Mathisen <terje.m...@tmsw.no> schrieb:
> >> BGB wrote:
> >
> >>> Australia has completely banned aluminum wiring for pretty much everything.
> >>>
> >>> In the US it was just sorta "strongly unpopular" for a while, but
> >>> apparently is back in style again due to rising costs.
> >>
> >> Aluminium is great for high-voltage/high-power cables since the
> >> conductivity per kg is better than Copper?
> >
> > The problem is the oxide layer, which is highly resistive and,
> > if you're unlucky, can generate fires.
> >
> >>> Granted, this could be a point of divergence between US engineering (use
> >>> 18 AWG because the NEC says so) and Chinese engineering (use the
> >>> cheapest wire possible that is still thick enough that it probably wont
> >>> catch fire under expected load).
> >>
> >> The solution here is to get rid of all 110V wiring and devices,
> >> preferably going all the way to 400V which reduces resistive losses by a
> >> factor of about 15.
> >
> > 110 V is rather safe 230 V is less safe, but you still need to be
> > unlucky to be killed. At least one family member would not be
> > alive today if we had 400 V (unless you mean three phases, in
> > which case you are unlikely to touch two of them at the same time).
> >
> Is this something you know? I.e. you have some references I can go through?
>
> Voltage mostly doesn't matter, current is what burns you.
> Frequencies that interact with heart signalling are much more
> problematic, and 50-60 Hz seems to be a bad range.
<
Yes, it is current that gives you the Zap !
But it is voltage that cause the current to flow (through the resistance
in your skin) in the first place. If the voltage source does not have low enough
output impedance the voltage will disappear (become lower) faster than
the current will burn you.
<
And yes, I have, personally, been thrown across the room after touching
something in the 400V range.
<
In any event the danger increases with the square of voltage.
<
> Terje
>
> --
> - <Terje.Mathisen at tmsw.no>
> "almost all programming can be viewed as an exercise in caching"

On Friday, October 22, 2021 at 3:11:12 PM UTC-5, BGB wrote:
> On 10/22/2021 1:37 PM, MitchAlsup wrote:
> > On Friday, October 22, 2021 at 1:30:17 PM UTC-5, BGB wrote:
> >> On 10/22/2021 9:08 AM, Terje Mathisen wrote:
> >
> >>>> In the US it was just sorta "strongly unpopular" for a while, but
> >>>> apparently is back in style again due to rising costs.
> >>>
> >>> Aluminium is great for high-voltage/high-power cables since the
> >>> conductivity per kg is better than Copper?
> > <
> >> Yeah, in terms of power to weight, aluminum (and magnesium) wire are a
> >> lot better than copper.
> >>
> >> Magnesium wire has the main obvious drawback of being highly flammable,
> >> and once it gets burning, water will not be able to put it out. Aluminum
> >> wire is at least not (actively) flammable.
> > <
> > You might want to lookup why the HMS Sheffield was lost in the Falklands
> > War............its aluminum superstructure caught fire and could not be put out.......
> Granted, aluminum can catch fire in certain cases.
>
>
> I guess there was also a ship a few years back that was trying mostly to
> ship a hull full of machining chips over to China to sell as scrap.
>
> The chips caught fire, they tried to put it out with seawater, but this
> only made it worse, and the ship sank.
>
>
> But, in most normal conditions, if you try to light up a piece of
> aluminum, it will not burn.
<
You (ahem) obviously do not know of the equipment I can bring to Pyrotechnics..........
>
>
> This is unlike magnesium, which is significantly more flammable. Put
> enough heat on it, or drop another piece of burning magnesium on it, ...
> and there it goes.

On 10/22/2021 3:34 PM, Terje Mathisen wrote:
> BGB wrote:
>> Actually, some of us would also like active power backup for houses,
>> built-in house scale surge suppression, ...
>>
>> So, the house could be its own UPS, rather than needing a bunch of
>> small UPS's all over the house to keep computers from getting messed
>> up (or to be able to keep them running for more than a few hours at a
>> time).
>>
>> Say, if one could have a house where the wall outlets always provided
>> a stable voltage with no momentary interruptions (and no voltage
>> spikes during bad weather, ...).
>>
>>
>> Getting 440V 3-phase utility power could also be useful, but typically
>> this is not available in areas that are zoned as residential (one
>> needs their own inverter to get this). There are 240V (single-phase)
>> to 440V (three phase) inverters available though.
>
> This is where I really pity those of you who ended up with 110V.
>>
>> In theory, one could put 240V wall outlets in a house as well, albeit
>> they have a different plug type under the NEMA system (and providing
>> both types of outlets without significantly increasing the amount of
>> house wiring would require using 4-conductor cables).
>
> We have, like the rest of Europe, 240V standard ("Shuko") outlets, for
> up to 16A fuse/13A continuous load. Going higher requires the big blue
> industrial outlets which are different for 16A vs 32A, or even larger
> red plugs with 5 pins, ground being longer than the others, which
> provides 3-phase 400V so that you can also extract 240V between ground
> and any of the phase lines.
>

Nothing, in theory, stops someone from installing Schuko plugs in US
houses. Apart from maybe building inspector people losing their crap
(well, and probably a person needing to do their own wiring job,
probably running 4-conductor cable to use them alongside the normal NEMA
plugs).

One can get 240V by wiring across the two hot wires from the utility
drop (this is commonly done already for things like clothes dryers and
electric stoves; albeit with different NEMA style plugs, which are also
annoyingly different depending on which sort of appliance is intended to
be plugged in).

So, there is typically only one spot in the house to plug in a dryer,
and another spot for a stove, and these two spots are not interchangeable.

> Here I am sitting just now, in our mountain cabin in Rauland Telemark,
> the local power company defaulted to 400V for all new installations,
> something which allowed me to put in a (max) 11 kW charger with cheap
> 5-wire 16A cable.
>
> The situation is much less nice down in Oslo where we have the infamous
> IT wiring standard, this is 240 V 3-phase with floating ground,
> something which we share with only Albania afaik. :-(
>

OK.

The US has several different systems:
240V, split into two 120V legs and a neutral;
Typical for residential drops.
440V/480V 3-phase, typical on most larger utility poles;
The split-phase us usually tapped between pairs of 3-phase legs.
Say, bigger street has 480V, taps off to 240 for smaller streets.
960V 3-phase, typical for industrial drops.
Stepped down to 440V and 240/120 by on-site transformers.

Then, also 208V or 208/240 high-leg delta.
These were for I guess when one wants to have split-phase and 3-phase on
the same utility poles. Gradually dying off.

Most plugs also have a ground wire. Typically, these all go back to the
breaker box, bolt up to the box, then the box has a ground spike
frequently directly below the breaker box, usually connected via a
heavier wire.

If it were up to me, it seems like it would make sense to have multiple
ground points around a house, both for redundancy (does grounding still
work effectively if the dirt is dry?...) or in-case a difference in
ground-level potential develops between one location and another
(though, this could lead to electrical conduction between the grounding
rods, which is a tradeoff).

> Terje
>

On 10/22/2021 1:37 PM, BGB wrote:
> On 10/22/2021 3:10 PM, Terje Mathisen wrote:
>> Thomas Koenig wrote:
>>> Terje Mathisen <terje.mathisen@tmsw.no> schrieb:
>>>> BGB wrote:
>>>
>>>>> Australia has completely banned aluminum wiring for pretty much
>>>>> everything.
>>>>>
>>>>> In the US it was just sorta "strongly unpopular" for a while, but
>>>>> apparently is back in style again due to rising costs.
>>>>
>>>> Aluminium is great for high-voltage/high-power cables since the
>>>> conductivity per kg is better than Copper?
>>>
>>> The problem is the oxide layer, which is highly resistive and,
>>> if you're unlucky, can generate fires.
>>>
>>>>> Granted, this could be a point of divergence between US engineering
>>>>> (use
>>>>> 18 AWG because the NEC says so) and Chinese engineering (use the
>>>>> cheapest wire possible that is still thick enough that it probably
>>>>> wont
>>>>> catch fire under expected load).
>>>>
>>>> The solution here is to get rid of all 110V wiring and devices,
>>>> preferably going all the way to 400V which reduces resistive losses
>>>> by a
>>>> factor of about 15.
>>>
>>> 110 V is rather safe   230 V is less safe, but you still need to be
>>> unlucky to be killed.  At least one family member would not be
>>> alive today if we had 400 V (unless you mean three phases, in
>>> which case you are unlikely to touch two of them at the same time).
>>>
>> Is this something you know? I.e. you have some references I can go
>> through?
>>
>> Voltage mostly doesn't matter, current is what burns you.
>
> Humans are also big resistors in this sense (wet skin contact is
> typically several kOhm; dry skin contact typically much higher).
>
> So, the current through a human will depend highly on the voltage and
> how far away the contact points are, ...
>
> Likewise, lower voltages are safer because humans inherent resistance is
> enough to reduce the current through them to "reasonably safe" levels.
>
>
> Whereas, higher voltages don't care, they will go where they are going
> to go...
>
>
>
>> Frequencies that interact with heart signalling are much more
>> problematic, and 50-60 Hz seems to be a bad range.
>>
>
> Generally, this as well.
>
> Probably 240Hz or 480Hz could be better, allowing smaller and more
> efficient transformers, while not being high enough to turn ones' house
> wiring into a giant radio transmitter (eg: kHz range).
>
> Going too much higher than this would probably be a bad thing due to RF
> emissions and leakage.
>

Rule of thumb from ham days: a person is a one megohm one watt resistor.

On 10/22/2021 2:24 PM, MitchAlsup wrote:
> On Friday, October 22, 2021 at 3:11:12 PM UTC-5, BGB wrote:
>> On 10/22/2021 1:37 PM, MitchAlsup wrote:
>>> On Friday, October 22, 2021 at 1:30:17 PM UTC-5, BGB wrote:
>>>> On 10/22/2021 9:08 AM, Terje Mathisen wrote:
>>>
>>>>>> In the US it was just sorta "strongly unpopular" for a while, but
>>>>>> apparently is back in style again due to rising costs.
>>>>>
>>>>> Aluminium is great for high-voltage/high-power cables since the
>>>>> conductivity per kg is better than Copper?
>>> <
>>>> Yeah, in terms of power to weight, aluminum (and magnesium) wire are a
>>>> lot better than copper.
>>>>
>>>> Magnesium wire has the main obvious drawback of being highly flammable,
>>>> and once it gets burning, water will not be able to put it out. Aluminum
>>>> wire is at least not (actively) flammable.
>>> <
>>> You might want to lookup why the HMS Sheffield was lost in the Falklands
>>> War............its aluminum superstructure caught fire and could not be put out.......
>> Granted, aluminum can catch fire in certain cases.
>>
>>
>> I guess there was also a ship a few years back that was trying mostly to
>> ship a hull full of machining chips over to China to sell as scrap.
>>
>> The chips caught fire, they tried to put it out with seawater, but this
>> only made it worse, and the ship sank.
>>
>>
>> But, in most normal conditions, if you try to light up a piece of
>> aluminum, it will not burn.
> <
> You (ahem) obviously do not know of the equipment I can bring to Pyrotechnics..........

https://en.wikipedia.org/wiki/Thermite

>>
>>
>> This is unlike magnesium, which is significantly more flammable. Put
>> enough heat on it, or drop another piece of burning magnesium on it, ...
>> and there it goes.

On Friday, October 22, 2021 at 4:39:30 PM UTC-5, BGB wrote:
> On 10/22/2021 3:34 PM, Terje Mathisen wrote:
> > BGB wrote:
> >> Actually, some of us would also like active power backup for houses,
> >> built-in house scale surge suppression, ...
> >>
> >> So, the house could be its own UPS, rather than needing a bunch of
> >> small UPS's all over the house to keep computers from getting messed
> >> up (or to be able to keep them running for more than a few hours at a
> >> time).
> >>
> >> Say, if one could have a house where the wall outlets always provided
> >> a stable voltage with no momentary interruptions (and no voltage
> >> spikes during bad weather, ...).
> >>
> >>
> >> Getting 440V 3-phase utility power could also be useful, but typically
> >> this is not available in areas that are zoned as residential (one
> >> needs their own inverter to get this). There are 240V (single-phase)
> >> to 440V (three phase) inverters available though.
> >
> > This is where I really pity those of you who ended up with 110V.
> >>
> >> In theory, one could put 240V wall outlets in a house as well, albeit
> >> they have a different plug type under the NEMA system (and providing
> >> both types of outlets without significantly increasing the amount of
> >> house wiring would require using 4-conductor cables).
> >
> > We have, like the rest of Europe, 240V standard ("Shuko") outlets, for
> > up to 16A fuse/13A continuous load. Going higher requires the big blue
> > industrial outlets which are different for 16A vs 32A, or even larger
> > red plugs with 5 pins, ground being longer than the others, which
> > provides 3-phase 400V so that you can also extract 240V between ground
> > and any of the phase lines.
> >
> Nothing, in theory, stops someone from installing Schuko plugs in US
> houses. Apart from maybe building inspector people losing their crap
> (well, and probably a person needing to do their own wiring job,
> probably running 4-conductor cable to use them alongside the normal NEMA
> plugs).
>
>
> One can get 240V by wiring across the two hot wires from the utility
> drop (this is commonly done already for things like clothes dryers and
> electric stoves; albeit with different NEMA style plugs, which are also
> annoyingly different depending on which sort of appliance is intended to
> be plugged in).
<
What you really want to say is:: one can get two 120V lines out of the 240
3-wire lines. Pos, Neutral, Neg:: Pos-Neg = 240V, Neutral-Neg = 120V,
Pos-Neutral = 120V.
>
> So, there is typically only one spot in the house to plug in a dryer,
> and another spot for a stove, and these two spots are not interchangeable.
<
I have seven 30A 240V drops in my machine shop.
<
> > Here I am sitting just now, in our mountain cabin in Rauland Telemark,
> > the local power company defaulted to 400V for all new installations,
> > something which allowed me to put in a (max) 11 kW charger with cheap
> > 5-wire 16A cable.
> >
> > The situation is much less nice down in Oslo where we have the infamous
> > IT wiring standard, this is 240 V 3-phase with floating ground,
> > something which we share with only Albania afaik. :-(
> >
> OK.
>
> The US has several different systems:
> 240V, split into two 120V legs and a neutral;
> Typical for residential drops.
> 440V/480V 3-phase, typical on most larger utility poles;
> The split-phase us usually tapped between pairs of 3-phase legs.
> Say, bigger street has 480V, taps off to 240 for smaller streets.
> 960V 3-phase, typical for industrial drops.
> Stepped down to 440V and 240/120 by on-site transformers.
>
> Then, also 208V or 208/240 high-leg delta.
> These were for I guess when one wants to have split-phase and 3-phase on
> the same utility poles. Gradually dying off.
>
> Most plugs also have a ground wire. Typically, these all go back to the
> breaker box, bolt up to the box, then the box has a ground spike
> frequently directly below the breaker box, usually connected via a
> heavier wire.
<
There are 3 wires coming down from the pole {Pos, Neutral, Neg} a 4th
wire is added by grounding the house {Gnd}. The transformer on the pole
is also grounded, but there can be significant noise between house ground
and pole Neutral. House Gnd is present to direct lightening strikes from
the house into the ground and avoid directing it up to the pole and into
neighboring houses.
>
> If it were up to me, it seems like it would make sense to have multiple
> ground points around a house, both for redundancy (does grounding still
> work effectively if the dirt is dry?...) or in-case a difference in
> ground-level potential develops between one location and another
> (though, this could lead to electrical conduction between the grounding
> rods, which is a tradeoff).
<
Grounding poles have a specified distance into the ground they have to
be pounded.
<
Neutral and Ground are together known as "bonding" in the wiring code
of Austin Texas.
>
>
> > Terje
> >

On Friday, October 22, 2021 at 4:40:17 PM UTC-5, Ivan Godard wrote:
> On 10/22/2021 1:37 PM, BGB wrote:
> > On 10/22/2021 3:10 PM, Terje Mathisen wrote:

> >
> > Going too much higher than this would probably be a bad thing due to RF
> > emissions and leakage.
> >
> Rule of thumb from ham days: a person is a one megohm one watt resistor.
<
But you only need two handful of milliAmps to take a good day and ruin it.

On 10/22/2021 8:04 PM, MitchAlsup wrote:
> On Friday, October 22, 2021 at 4:39:30 PM UTC-5, BGB wrote:
>> On 10/22/2021 3:34 PM, Terje Mathisen wrote:
>>> BGB wrote:
>>>> Actually, some of us would also like active power backup for houses,
>>>> built-in house scale surge suppression, ...
>>>>
>>>> So, the house could be its own UPS, rather than needing a bunch of
>>>> small UPS's all over the house to keep computers from getting messed
>>>> up (or to be able to keep them running for more than a few hours at a
>>>> time).
>>>>
>>>> Say, if one could have a house where the wall outlets always provided
>>>> a stable voltage with no momentary interruptions (and no voltage
>>>> spikes during bad weather, ...).
>>>>
>>>>
>>>> Getting 440V 3-phase utility power could also be useful, but typically
>>>> this is not available in areas that are zoned as residential (one
>>>> needs their own inverter to get this). There are 240V (single-phase)
>>>> to 440V (three phase) inverters available though.
>>>
>>> This is where I really pity those of you who ended up with 110V.
>>>>
>>>> In theory, one could put 240V wall outlets in a house as well, albeit
>>>> they have a different plug type under the NEMA system (and providing
>>>> both types of outlets without significantly increasing the amount of
>>>> house wiring would require using 4-conductor cables).
>>>
>>> We have, like the rest of Europe, 240V standard ("Shuko") outlets, for
>>> up to 16A fuse/13A continuous load. Going higher requires the big blue
>>> industrial outlets which are different for 16A vs 32A, or even larger
>>> red plugs with 5 pins, ground being longer than the others, which
>>> provides 3-phase 400V so that you can also extract 240V between ground
>>> and any of the phase lines.
>>>
>> Nothing, in theory, stops someone from installing Schuko plugs in US
>> houses. Apart from maybe building inspector people losing their crap
>> (well, and probably a person needing to do their own wiring job,
>> probably running 4-conductor cable to use them alongside the normal NEMA
>> plugs).
>>
>>
>> One can get 240V by wiring across the two hot wires from the utility
>> drop (this is commonly done already for things like clothes dryers and
>> electric stoves; albeit with different NEMA style plugs, which are also
>> annoyingly different depending on which sort of appliance is intended to
>> be plugged in).
> <
> What you really want to say is:: one can get two 120V lines out of the 240
> 3-wire lines. Pos, Neutral, Neg:: Pos-Neg = 240V, Neutral-Neg = 120V,
> Pos-Neutral = 120V.

More or less, except that the two ends of the circuit are usually both
labeled as "hot", AFAIK.

Standard color-scheme is usually:
Black: Hot
White: Neutral
Green: Ground (may be non-insulated in romex wire)

Or, for 240V:
Black: Hot (one side)
Red: Hot (other side)
White: Neutral
Green: Ground

For 3 phase, it might be different:
Black, Red, Blue: Hot Legs
Green: Neutral

>>
>> So, there is typically only one spot in the house to plug in a dryer,
>> and another spot for a stove, and these two spots are not interchangeable.
> <
> I have seven 30A 240V drops in my machine shop.
> <

Granted, but this is not a standard feature in residential settings.

Most(?) people have to live with only a stove and/or dryer.

Parents recently bought a house for my brother, house has apparently a
40A service drop, two 120V circuits, and a single 240V circuit.

Granted, it is not a particularly big house:
~ 400 sq ft;
Living Room;
Bedroom;
Kitchen;
Bathroom.

Single story.

Parents are in the process of replacing most of the floors and repairing
the roof, because the roof was leaky and the floors were generally rotted.

Current house (technically parents' house) is a fair bit bigger (~ 1000
sq ft), with 3 bedrooms and 2 bathrooms, front room, kitchen, and
laundry room.
Also single story.

Also has considerably more going on in the breaker box.

>>> Here I am sitting just now, in our mountain cabin in Rauland Telemark,
>>> the local power company defaulted to 400V for all new installations,
>>> something which allowed me to put in a (max) 11 kW charger with cheap
>>> 5-wire 16A cable.
>>>
>>> The situation is much less nice down in Oslo where we have the infamous
>>> IT wiring standard, this is 240 V 3-phase with floating ground,
>>> something which we share with only Albania afaik. :-(
>>>
>> OK.
>>
>> The US has several different systems:
>> 240V, split into two 120V legs and a neutral;
>> Typical for residential drops.
>> 440V/480V 3-phase, typical on most larger utility poles;
>> The split-phase us usually tapped between pairs of 3-phase legs.
>> Say, bigger street has 480V, taps off to 240 for smaller streets.
>> 960V 3-phase, typical for industrial drops.
>> Stepped down to 440V and 240/120 by on-site transformers.
>>
>> Then, also 208V or 208/240 high-leg delta.
>> These were for I guess when one wants to have split-phase and 3-phase on
>> the same utility poles. Gradually dying off.
>>
>> Most plugs also have a ground wire. Typically, these all go back to the
>> breaker box, bolt up to the box, then the box has a ground spike
>> frequently directly below the breaker box, usually connected via a
>> heavier wire.
> <
> There are 3 wires coming down from the pole {Pos, Neutral, Neg} a 4th
> wire is added by grounding the house {Gnd}. The transformer on the pole
> is also grounded, but there can be significant noise between house ground
> and pole Neutral. House Gnd is present to direct lightening strikes from
> the house into the ground and avoid directing it up to the pole and into
> neighboring houses.

Yeah.

>>
>> If it were up to me, it seems like it would make sense to have multiple
>> ground points around a house, both for redundancy (does grounding still
>> work effectively if the dirt is dry?...) or in-case a difference in
>> ground-level potential develops between one location and another
>> (though, this could lead to electrical conduction between the grounding
>> rods, which is a tradeoff).
> <
> Grounding poles have a specified distance into the ground they have to
> be pounded.
> <
> Neutral and Ground are together known as "bonding" in the wiring code
> of Austin Texas.

I just wonder if there is a reason why they use only a single grounding
rod per house rather than, say, 4 of them. Dirt has a fairly high
resistance, and it seems like with 4 rods one could keep the
house-ground roughly equal to the dirt at all points around the house,
rather than just at a single point.

Then again, if a long-lasting gradient were present, current could flow
up one ground rod and over to another, which I guess could potentially
lead to corrosion issues if it were a long-standing issue.

Though, it could make more sense if Faraday cages were a standard
feature in houses, which, granted, they are not.

>>
>>
>>> Terje
>>>

On Friday, October 22, 2021 at 8:08:39 AM UTC-6, Terje Mathisen wrote:
> BGB wrote:

> > In the US it was just sorta "strongly unpopular" for a while, but
> > apparently is back in style again due to rising costs.

> Aluminium is great for high-voltage/high-power cables since the
> conductivity per kg is better than Copper?

Oh, yes. Plus it doesn't get stolen by copper thieves.

But when it comes to house wiring - it's so easy to make a little
mistake, leading to a poor contact starting a fire.

John Savard

On Friday, October 22, 2021 at 8:08:39 AM UTC-6, Terje Mathisen wrote:

> The solution here is to get rid of all 110V wiring and devices,
> preferably going all the way to 400V which reduces resistive losses by a
> factor of about 15.

We've already gone to AC, which means that the voltage is only
reduced to 110 volts, for increased safety, *within the household*,
because transformers can easily produce that lower voltage from
a higher voltage used in power lines. So the extra resistive losses
caused by the lower voltage are only the minimum necessary for
safety.

Actually, the U.S. uses 120 volts rms, and Japan uses 100 volts
rms. It's *Canada* that uses 110 volts rms, IIRC.

John Savard

MitchAlsup <MitchAlsup@aol.com> wrote:
> On Friday, October 22, 2021 at 1:30:17 PM UTC-5, BGB wrote:
>> On 10/22/2021 9:08 AM, Terje Mathisen wrote:
>
>>>> In the US it was just sorta "strongly unpopular" for a while, but
>>>> apparently is back in style again due to rising costs.
>>>
>>> Aluminium is great for high-voltage/high-power cables since the
>>> conductivity per kg is better than Copper?
> <
>> Yeah, in terms of power to weight, aluminum (and magnesium) wire are a
>> lot better than copper.
>>
>> Magnesium wire has the main obvious drawback of being highly flammable,
>> and once it gets burning, water will not be able to put it out. Aluminum
>> wire is at least not (actively) flammable.
> <
> You might want to lookup why the HMS Sheffield was lost in the Falklands
> War............its aluminum superstructure caught fire and could not be put out.......

You need to check HMS Sheffield in Wikipedia because it was not made of
aluminum.
What caught fire was the plastic wire insulation creating toxic black smoke
making fire fighting near impossible. Power conduits between bulkheads were
not sealed allowing the fire to spread.

>> In terms of power vs wire gauge, aluminum is worse (need a thicker wire
>> to carry similar current). One needs to increase the wire thickness by
>> around 2 AWG to have similar ampacity.
>>
>> A lot of the people doing the whole "aluminum wiring sucks" thing are
>> often trying to compare copper wire and aluminum wire at the same
>> thickness, rather than comparing a copper wire to an aluminum wire with
>> a 2 AWG adjustment.
>>
>> Though, in theory, if wiring up a house with aluminum, one would ideally
>> want to be wiring up their 20A circuits with 10 AWG rather than 12 AWG.
> <
> Yes, indeed, "done to code" is a euphemism for "the wires are 1 AWG too small"
> And that is in copper.

On 2021-10-22 17:08, Terje Mathisen wrote:
> BGB wrote:
>> On 10/21/2021 6:57 PM, MitchAlsup wrote:
>>> On Tuesday, October 19, 2021 at 4:11:42 PM UTC-5, BGB wrote:

[snip]

>>>> Batteries: LiON has a limited lifespan and some other issues.
>>> <
>>> Melt the lithium down and make new batteries.
>>
>> Could be, or maybe set them on fire and collect lithium oxide and
>> cobalt from the smoke...
>>
>> Guess it depends on how much of the materials could be recovered this
>> way.

IIRC this interesting article on battery recycling has not been
referenced in this thread:

"Study: Recycled Lithium Batteries as Good as Newly Mined - Cathodes
made with novel direct-recycling beat commercial materials"

https://spectrum.ieee.org/recycled-batteries-good-as-newly-mined

On Fr 22 Okt 2021 at 16:07, Thomas Koenig <tkoenig@netcologne.de> wrote:

> Terje Mathisen <terje.mathisen@tmsw.no> schrieb:
>> BGB wrote:
>> The solution here is to get rid of all 110V wiring and devices,
>> preferably going all the way to 400V which reduces resistive losses by a
>> factor of about 15.
> 110 V is rather safe 230 V is less safe, but you still need to be
> unlucky to be killed. At least one family member would not be
> alive today if we had 400 V (unless you mean three phases, in
> which case you are unlikely to touch two of them at the same time).

Well, I was unlucky once and touched a 3 phase line. I had a sore arm
for a few days and I would not like to relive the experience.

'Andreas

On Saturday, October 23, 2021 at 4:05:23 AM UTC+3, MitchAlsup wrote:
> On Friday, October 22, 2021 at 4:40:17 PM UTC-5, Ivan Godard wrote:
> > On 10/22/2021 1:37 PM, BGB wrote:
> > > On 10/22/2021 3:10 PM, Terje Mathisen wrote:
>
> > >
> > > Going too much higher than this would probably be a bad thing due to RF
> > > emissions and leakage.
> > >
> > Rule of thumb from ham days: a person is a one megohm one watt resistor.
> <
> But you only need two handful of milliAmps to take a good day and ruin it.

That's very far from what I remember.
100-200 mA - could kill quickly. But one can get lucky, too
10mA - you certainly feel it, it could be painful and can be lethal if applied for a few minutes
2mA - you don't feel it under normal circumstances, i.e. when you don't lick wire or something similar.

On Friday, October 22, 2021 at 11:05:41 PM UTC-5, BGB wrote:
> On 10/22/2021 8:04 PM, MitchAlsup wrote:

> >> If it were up to me, it seems like it would make sense to have multiple
> >> ground points around a house, both for redundancy (does grounding still
> >> work effectively if the dirt is dry?...) or in-case a difference in
> >> ground-level potential develops between one location and another
> >> (though, this could lead to electrical conduction between the grounding
> >> rods, which is a tradeoff).
> > <
> > Grounding poles have a specified distance into the ground they have to
> > be pounded.
> > <
> > Neutral and Ground are together known as "bonding" in the wiring code
> > of Austin Texas.
<
> I just wonder if there is a reason why they use only a single grounding
> rod per house rather than, say, 4 of them. Dirt has a fairly high
> resistance, and it seems like with 4 rods one could keep the
> house-ground roughly equal to the dirt at all points around the house,
> rather than just at a single point.
<
The current Austin Code requires an individual Gnd for each "service"
panel. My machine shop is in the 3rd unit of a duplex I own. There are 3
sets of Gnd wires, so lightning in unit 1 does not blow up unit 2 (or 3).
The code in place when the building was built (1950s) had a single Gnd
and all rooms were on a single service.
>
> Then again, if a long-lasting gradient were present, current could flow
> up one ground rod and over to another, which I guess could potentially
> lead to corrosion issues if it were a long-standing issue.
>
> Though, it could make more sense if Faraday cages were a standard
> feature in houses, which, granted, they are not.
>
>
> >>
> >>
> >>> Terje
> >>>

Andreas Eder wrote:
> On Fr 22 Okt 2021 at 16:07, Thomas Koenig <tkoenig@netcologne.de> wrote:
>
>> Terje Mathisen <terje.mathisen@tmsw.no> schrieb:
>>> BGB wrote:
>>> The solution here is to get rid of all 110V wiring and devices,
>>> preferably going all the way to 400V which reduces resistive losses by a
>>> factor of about 15.
>> 110 V is rather safe 230 V is less safe, but you still need to be
>> unlucky to be killed. At least one family member would not be
>> alive today if we had 400 V (unless you mean three phases, in
>> which case you are unlikely to touch two of them at the same time).
>
> Well, I was unlucky once and touched a 3 phase line. I had a sore arm
> for a few days and I would not like to relive the experience.
>
> 'Andreas

I once worked with a former IBM mainframe service technician who was
missing his ring finger. The story he told was that it seems he forgot
the rule about always remove all jewelry, rings, watches, tie-clips before
working on electronic equipment and left his ring on. His ring
accidentally shorted a power capacitor which was not fully discharged.
There was a bang and a flash as the ring absorbed all the energy and
instantly heated to molten metal, his finger flew off one direction
while he was knocked across the room.

On 10/23/2021 11:21 AM, Michael S wrote:
> On Saturday, October 23, 2021 at 4:05:23 AM UTC+3, MitchAlsup wrote:
>> On Friday, October 22, 2021 at 4:40:17 PM UTC-5, Ivan Godard wrote:
>>> On 10/22/2021 1:37 PM, BGB wrote:
>>>> On 10/22/2021 3:10 PM, Terje Mathisen wrote:
>>
>>>>
>>>> Going too much higher than this would probably be a bad thing due to RF
>>>> emissions and leakage.
>>>>
>>> Rule of thumb from ham days: a person is a one megohm one watt resistor.
>> <
>> But you only need two handful of milliAmps to take a good day and ruin it.
>
> That's very far from what I remember.
> 100-200 mA - could kill quickly. But one can get lucky, too
> 10mA - you certainly feel it, it could be painful and can be lethal if applied for a few minutes
> 2mA - you don't feel it under normal circumstances, i.e. when you don't lick wire or something similar.
>

Looking stuff up, measuring stuff, ... it seems mixed.
If I hold the multi-meter probes, one in each hand:
Dry skin: 1.5 MOhm;
Wet skin: 200 kOhm.

Hand-to-mouth, wet skin: ~ 80kOhm (namely, one hand holding the probe in
water, other probe in mouth).

I get somewhat lower values (~ 10k) if both probes are in mouth, but
that is not the point (*).

*: Admittedly, I sometimes use tongue to estimate battery voltage if a
multimeter isn't readily available, usually:
slight sting: ~ 8-12v (much over 12v = somewhat painful)
metal flavor: ~ 5-7v

Can't really measure AAs because the voltage is too low to be perceptible.

For things like car-batteries or similar, there is the "wet fingers on a
single hand and touch both terminals" method, which works under a
similar premise to the tongue method, but works better for 12-24v volts.

This method doesn't work with 2 hands.

At least, if the electrical path is through the hands, it seems either
exceeding the "let go" threshold, or getting a "potentially lethal"
current through the heart, is unlikely (though, claims vary widely as to
what this is; some say a few milliamps, other things claim that the
value is in micro-amp territory).

If one assumes a 1mA cutoff, then it seems relatively unlikely that a
person could get this with 120V short of both contact points being on
their chest or similar (or face-to-chest, or something to this effect).

Some stuff claims that it exceeds the "let go" current and the person
would be electrocuted via prolonged exposure, however, this only seems
likely if both contact points are on the arm, which would then (by
definition) not lead to a path through the heart.

My own experience with coming in contact with 120VAC has usually been an
unpleasant buzzing sensation.

Most unpleasant experience I can remember with 120VAC was trying to work
with a cord in an awkward location, and managing to get a finger in
contact with both terminals at the same time, which had "a fairly
obvious stinging sensation".

If handling 48V (typically DC), I can usually handle bare wires and not
feel anything. If skin is wet, then there can be a sting at the point of
contact at 24-48v.

Not sure how it would be with AC, it seems possible that its "buzzing"
nature could make it easier to feel.

Claims about body resistance also vary wildly though.

Sees a video where they have a bunch of people going and touching a
multi-meter, it seems that resistance can vary by a fairly large margin.

A lot of the people were measuring in the 200-400 kOhm range, a few
people measured much lower (~ 20-60 kOhm). Didn't appear obviously
correlated to body size.

This implies that maybe some people face a much bigger threat to
electricity than others.

Like, a person with a 20-60 kOhm resistance could not casually handle
live 48v wiring without feeling anything?...

The guy starting the video commented that he was testing if it depended
on gender. But, the results in the video didn't seem to have any obvious
gender correlation.

I am guessing it is more likely a physiological factor, such as their
electrolyte levels?...

My own resistance values seem mostly in range of those expected if I
were made mostly out of tap-water.

....

On 10/20/21 19:42, BGB wrote:

> Except for cost cutting.
>
>
> Say they use a motor which needs to be run on the edge of burning up
> just to be able to accelerate within a reasonable time-frame; and safer
> thermal margins would eat too much into the user-experienced performance
> characteristics (say, for example, they tune things such that the motor
> operates up to 200C, with the coating on the windings decomposing at
> 250C; but say the internal temperature of the windings during
> acceleration reaches 250C before it hits 200C on the sensor, ...).
>

Motors used for such applications have power limiting built in to the
controller electronics, which includes temperature sensing to limit
input power to a safe level.

>
> If it is a common failure mode for things like blenders and vacuum
> cleaners, it doesn't seem like too much of a stretch for EVs if the
> companies start trying to cut costs by using cheaper parts.
>

Blenders and cleaners use series wound motors typically, with windings
for the outer field and the rotating armature. They are cheap and have
the correct torque speed characteristics. Neither they, nor single
or three phase induction motors would burn out on reduced voltage. Just
the the torque would be reduced.

In general, batteries are impractical for grid scale energy storage,
because the sheer volume, weight and cost involved. Also, short design
life when used in cycling mode. Five minute of simple arithmetic
would tell you that...

Chris

MitchAlsup wrote:
> On Friday, October 22, 2021 at 3:11:12 PM UTC-5, BGB wrote:
>> Granted, aluminum can catch fire in certain cases.
>>
>>
>> I guess there was also a ship a few years back that was trying mostly to
>> ship a hull full of machining chips over to China to sell as scrap.
>>
>> The chips caught fire, they tried to put it out with seawater, but this
>> only made it worse, and the ship sank.
>>
>>
>> But, in most normal conditions, if you try to light up a piece of
>> aluminum, it will not burn.
> <
> You (ahem) obviously do not know of the equipment I can bring to Pyrotechnics..........
>>
>>
>> This is unlike magnesium, which is significantly more flammable. Put
>> enough heat on it, or drop another piece of burning magnesium on it, ...
>> and there it goes.

The old Hydro used to have both Al and Mg melters, I did a work week
placement in secondary school in the Mg laboratory at Herøya:

Having access to both 800-1200 C ovens and unlimited amounts of Mg
shavings meant that I could generate as many pyro flashes as I wanted.

We got samples of every set of bars casted, in the form of an extra plug
in the casting forms, sent over in pneumatic tubes: These we had to
shave smooth before putting them in the analyzer to verify the purity
and/or exact metal mixture.

In comparison Al is _very_ hard to burn.

Terje

--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

On Sunday, October 24, 2021 at 7:47:56 AM UTC-5, chris wrote:
> On 10/20/21 19:42, BGB wrote:
>
> > Except for cost cutting.
> >
> >
> > Say they use a motor which needs to be run on the edge of burning up
> > just to be able to accelerate within a reasonable time-frame; and safer
> > thermal margins would eat too much into the user-experienced performance
> > characteristics (say, for example, they tune things such that the motor
> > operates up to 200C, with the coating on the windings decomposing at
> > 250C; but say the internal temperature of the windings during
> > acceleration reaches 250C before it hits 200C on the sensor, ...).
> >
>
> Motors used for such applications have power limiting built in to the
> controller electronics, which includes temperature sensing to limit
> input power to a safe level.
>
> >
> > If it is a common failure mode for things like blenders and vacuum
> > cleaners, it doesn't seem like too much of a stretch for EVs if the
> > companies start trying to cut costs by using cheaper parts.
> >
>
> Blenders and cleaners use series wound motors typically, with windings
> for the outer field and the rotating armature. They are cheap and have
> the correct torque speed characteristics. Neither they, nor single
> or three phase induction motors would burn out on reduced voltage. Just
> the the torque would be reduced.
<
So guess what happens in an induction motor that is fed lower than expected
voltage ?
>
> In general, batteries are impractical for grid scale energy storage,
> because the sheer volume, weight and cost involved. Also, short design
> life when used in cycling mode. Five minute of simple arithmetic
> would tell you that...
>
> Chris

On Sunday, October 24, 2021 at 7:51:32 AM UTC-5, Terje Mathisen wrote:
> MitchAlsup wrote:
> > On Friday, October 22, 2021 at 3:11:12 PM UTC-5, BGB wrote:
> >> Granted, aluminum can catch fire in certain cases.
> >>
> >>
> >> I guess there was also a ship a few years back that was trying mostly to
> >> ship a hull full of machining chips over to China to sell as scrap.
> >>
> >> The chips caught fire, they tried to put it out with seawater, but this
> >> only made it worse, and the ship sank.
> >>
> >>
> >> But, in most normal conditions, if you try to light up a piece of
> >> aluminum, it will not burn.
> > <
> > You (ahem) obviously do not know of the equipment I can bring to Pyrotechnics..........
> >>
> >>
> >> This is unlike magnesium, which is significantly more flammable. Put
> >> enough heat on it, or drop another piece of burning magnesium on it, ....
> >> and there it goes.
> The old Hydro used to have both Al and Mg melters, I did a work week
> placement in secondary school in the Mg laboratory at Herøya:
>
> Having access to both 800-1200 C ovens and unlimited amounts of Mg
> shavings meant that I could generate as many pyro flashes as I wanted.
<
Maybe I should tell the tale of waxing the floor of the chem-lab with
nitrogen-tri-iodied...................
>
> We got samples of every set of bars casted, in the form of an extra plug
> in the casting forms, sent over in pneumatic tubes: These we had to
> shave smooth before putting them in the analyzer to verify the purity
> and/or exact metal mixture.
>
> In comparison Al is _very_ hard to burn.
> Terje
>
> --
> - <Terje.Mathisen at tmsw.no>
> "almost all programming can be viewed as an exercise in caching"

On 24/10/21 18:18, MitchAlsup wrote:
> On Sunday, October 24, 2021 at 7:51:32 AM UTC-5, Terje Mathisen wrote:
>> MitchAlsup wrote:
>>> On Friday, October 22, 2021 at 3:11:12 PM UTC-5, BGB wrote:
>>>> Granted, aluminum can catch fire in certain cases.
>>>>
>>>>
>>>> I guess there was also a ship a few years back that was trying mostly to
>>>> ship a hull full of machining chips over to China to sell as scrap.
>>>>
>>>> The chips caught fire, they tried to put it out with seawater, but this
>>>> only made it worse, and the ship sank.
>>>>
>>>>
>>>> But, in most normal conditions, if you try to light up a piece of
>>>> aluminum, it will not burn.
>>> <
>>> You (ahem) obviously do not know of the equipment I can bring to Pyrotechnics..........
>>>>
>>>>
>>>> This is unlike magnesium, which is significantly more flammable. Put
>>>> enough heat on it, or drop another piece of burning magnesium on it, ...
>>>> and there it goes.
>> The old Hydro used to have both Al and Mg melters, I did a work week
>> placement in secondary school in the Mg laboratory at Herøya:
>>
>> Having access to both 800-1200 C ovens and unlimited amounts of Mg
>> shavings meant that I could generate as many pyro flashes as I wanted.
> <
> Maybe I should tell the tale of waxing the floor of the chem-lab with
> nitrogen-tri-iodied...................

Must get rid of that lump of sodium in the garage. It is
too close to the powdered magnesium and potassium iodide :)

On 10/24/21 18:17, MitchAlsup wrote:
> On Sunday, October 24, 2021 at 7:47:56 AM UTC-5, chris wrote:
>> On 10/20/21 19:42, BGB wrote:
>>
>>> Except for cost cutting.
>>>
>>>
>>> Say they use a motor which needs to be run on the edge of burning up
>>> just to be able to accelerate within a reasonable time-frame; and safer
>>> thermal margins would eat too much into the user-experienced performance
>>> characteristics (say, for example, they tune things such that the motor
>>> operates up to 200C, with the coating on the windings decomposing at
>>> 250C; but say the internal temperature of the windings during
>>> acceleration reaches 250C before it hits 200C on the sensor, ...).
>>>
>>
>> Motors used for such applications have power limiting built in to the
>> controller electronics, which includes temperature sensing to limit
>> input power to a safe level.
>>
>>>
>>> If it is a common failure mode for things like blenders and vacuum
>>> cleaners, it doesn't seem like too much of a stretch for EVs if the
>>> companies start trying to cut costs by using cheaper parts.
>>>
>>
>> Blenders and cleaners use series wound motors typically, with windings
>> for the outer field and the rotating armature. They are cheap and have
>> the correct torque speed characteristics. Neither they, nor single
>> or three phase induction motors would burn out on reduced voltage. Just
>> the the torque would be reduced.
> <
> So guess what happens in an induction motor that is fed lower than expected
> voltage ?

As I said, reduced torque and if the load is significant, the motor rpm
will drop as well. Induction motors are designed for a given slip speed
at full load, which always less then than theoretical hz x number of
poles. Overloading a motor increases the line current and will
overheat or burn out if continuous. Undervoltage reduces the current,
since the inductance of the windings stays constant...

Chris

>>
>> In general, batteries are impractical for grid scale energy storage,
>> because the sheer volume, weight and cost involved. Also, short design
>> life when used in cycling mode. Five minute of simple arithmetic
>> would tell you that...
>>
>> Chris

On Sunday, October 24, 2021 at 4:39:56 PM UTC-5, chris wrote:
> On 10/24/21 18:17, MitchAlsup wrote:
> > On Sunday, October 24, 2021 at 7:47:56 AM UTC-5, chris wrote:
> >> On 10/20/21 19:42, BGB wrote:
> >>
> >>> Except for cost cutting.
> >>>
> >>>
> >>> Say they use a motor which needs to be run on the edge of burning up
> >>> just to be able to accelerate within a reasonable time-frame; and safer
> >>> thermal margins would eat too much into the user-experienced performance
> >>> characteristics (say, for example, they tune things such that the motor
> >>> operates up to 200C, with the coating on the windings decomposing at
> >>> 250C; but say the internal temperature of the windings during
> >>> acceleration reaches 250C before it hits 200C on the sensor, ...).
> >>>
> >>
> >> Motors used for such applications have power limiting built in to the
> >> controller electronics, which includes temperature sensing to limit
> >> input power to a safe level.
> >>
> >>>
> >>> If it is a common failure mode for things like blenders and vacuum
> >>> cleaners, it doesn't seem like too much of a stretch for EVs if the
> >>> companies start trying to cut costs by using cheaper parts.
> >>>
> >>
> >> Blenders and cleaners use series wound motors typically, with windings
> >> for the outer field and the rotating armature. They are cheap and have
> >> the correct torque speed characteristics. Neither they, nor single
> >> or three phase induction motors would burn out on reduced voltage. Just
> >> the the torque would be reduced.
> > <
> > So guess what happens in an induction motor that is fed lower than expected
> > voltage ?
> As I said, reduced torque and if the load is significant, the motor rpm
> will drop as well. Induction motors are designed for a given slip speed
> at full load, which always less then than theoretical hz x number of
> poles. Overloading a motor increases the line current and will
> overheat or burn out if continuous. Undervoltage reduces the current,
> since the inductance of the windings stays constant...
<
Err, no.
<
When an induction motor (key word induction) is fed to little voltage
the self inductance of the windings is not sufficient to stabilize the
input current and the motor starts to draw excessive current. Thus,
if voltage gets out of the 10%-ish range, the motor starts pulling
current quadratically wrt loss in voltage. This can cause the already
low voltage system to collapse (rapidly). It is the induction of the
windings that determines how much current the motor draws (max).
>
> Chris
> >>
> >> In general, batteries are impractical for grid scale energy storage,
> >> because the sheer volume, weight and cost involved. Also, short design
> >> life when used in cycling mode. Five minute of simple arithmetic
> >> would tell you that...
> >>
> >> Chris

On 10/24/21 23:58, MitchAlsup wrote:
> On Sunday, October 24, 2021 at 4:39:56 PM UTC-5, chris wrote:
>> On 10/24/21 18:17, MitchAlsup wrote:
>>> On Sunday, October 24, 2021 at 7:47:56 AM UTC-5, chris wrote:
>>>> On 10/20/21 19:42, BGB wrote:
>>>>
>>>>> Except for cost cutting.
>>>>>
>>>>>
>>>>> Say they use a motor which needs to be run on the edge of burning up
>>>>> just to be able to accelerate within a reasonable time-frame; and safer
>>>>> thermal margins would eat too much into the user-experienced performance
>>>>> characteristics (say, for example, they tune things such that the motor
>>>>> operates up to 200C, with the coating on the windings decomposing at
>>>>> 250C; but say the internal temperature of the windings during
>>>>> acceleration reaches 250C before it hits 200C on the sensor, ...).
>>>>>
>>>>
>>>> Motors used for such applications have power limiting built in to the
>>>> controller electronics, which includes temperature sensing to limit
>>>> input power to a safe level.
>>>>
>>>>>
>>>>> If it is a common failure mode for things like blenders and vacuum
>>>>> cleaners, it doesn't seem like too much of a stretch for EVs if the
>>>>> companies start trying to cut costs by using cheaper parts.
>>>>>
>>>>
>>>> Blenders and cleaners use series wound motors typically, with windings
>>>> for the outer field and the rotating armature. They are cheap and have
>>>> the correct torque speed characteristics. Neither they, nor single
>>>> or three phase induction motors would burn out on reduced voltage. Just
>>>> the the torque would be reduced.
>>> <
>>> So guess what happens in an induction motor that is fed lower than expected
>>> voltage ?
>> As I said, reduced torque and if the load is significant, the motor rpm
>> will drop as well. Induction motors are designed for a given slip speed
>> at full load, which always less then than theoretical hz x number of
>> poles. Overloading a motor increases the line current and will
>> overheat or burn out if continuous. Undervoltage reduces the current,
>> since the inductance of the windings stays constant...
> <
> Err, no.
> <
> When an induction motor (key word induction) is fed to little voltage
> the self inductance of the windings is not sufficient to stabilize the
> input current and the motor starts to draw excessive current. Thus,
> if voltage gets out of the 10%-ish range, the motor starts pulling
> current quadratically wrt loss in voltage. This can cause the already
> low voltage system to collapse (rapidly). It is the induction of the
> windings that determines how much current the motor draws (max).

Might be a bit rusty, but that first sentence is tripe, sorry. Motor
characteristics are complex and current is limited by the inductive
reactance of the windings. However, it's a bit more complicated.
A motor is effectively a transformer, with the rotor a shorted
secondary at stall, but generates it's own poles as the motor spins
up. Complex impedance, but because of the winding reactance, there's
no way that a reduced voltage would cause an increased current over
normal levels. Plenty of stuff on the web that will verify that.

One of the things we did in electronics was to study dc and ac
machines and it's been quite useful over the years when
designing power control circuits and sizing motors for the
workshop lathe and more...

Chris