Nice overview of the 240v US electrical system

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When I bought this house in '97, I realized I had a bit of re-wiring to do. So naturally I got a bit of information along the way.

 

My impression, from reading various books, is that the American 110 volt standard has more to do with an impression that it's safer for humans to be around. I don't know if that's true, but ...

 

Also, most American houses do not have "ring" type of circuits, such as might find in England. They are probably against code here.

 

American 220 obviously gets its higher voltage through a bit of slight of hand - the two legs are 180 degrees out of phase so the net difference between two 110 volt circuits is 220 volts. The problem is of course that a 220 volt American circuit has two "hot" wires and one "neutral" wire, and often there is no ground wire in older implementations. Of course newer installations would have four wires: the two hot 110 volt wires, the neutral wire, and the ground wire.

 

In my reading there was also a comment that the American system is more dependent upon larger conductor sizes, as the lower 110 voltage means for the same amount of watts (or power), the American wiring has to be about twice the current carrying capacity of the European circuit. Which means thicker wire, which means more copper. One book I consulted theorized it represents the American ability to have bigger stuff, or our greater wealth of natural resources (copper).  I dunno, but it makes a little sense.

 

There may also be less tendency for a 110 volt circuit to arc than a 220 volt circuit, but I doubt this was a design decision.

 

I *think* also that America was earlier than most of Europe in going electric. So the Europeans look at our standard and realized they could do it with less copper and perhaps better results.

 

Or we could just blame it all on Thomas Edison.

 

 
 
Anybody know the story on 50Hz euro standard?  It's like they were trying to get another thousand hours out of generator bearings at the expense of every service transformer being 20% larger.
 
US Electrical Panels

In the warehouse- museum We started out with two 200 Amp 3 Phase Square D panels, I had an electrical contractor add two additional 100 Amp single phase panels and I have added 5 additional 60 Amp single phase panels to get power closer to where we need it to save running hundreds of feet of cable and conduit for every appliance etc.

 

Everything must be in steel in the warehouse, and I do the same in my home, NO plastic outlet boxes or Romex [ plastic covered cable.

 

I have always found that electrical wiring buildings is one of the easiest things to understand and do yourself.

 

If you know what you are doing it will always work when you are done, unlike plumbing where you can do a major plumbing project in your home and you may have a little drip here and there that need a little tweaking.

 

John L.
 
reply to Combo post #10

Hi Combo

1. No way I could have pulled the plug. That was how mum got zapped. I would have had to reach over/past her to reach the plug, she had her hand on the flex only 2 or 3 inches behind the plug and she was blocking access. It would have been extremely risky to try to reach the plug, chances are I would have touched her hand. I was only less than 5 seconds from the fuse board.

2. "No safer to flick a switch than pull a plug..." well not if the plug is damaged, or in this case flex damaged just behind the plug. I have seen plenty of plugs damaged over the years, usually rewireable plugs that have a dirty or loose connection inside, sparking, smoking or burning - no way I would touch it without turning off the outlet first.

3. "more instinctive to pull a plug..." not for an Australian. We are completely used to switching off. We expect there to be a switch just above the socket and guess what? There it is...

Australian power outlets include the switch in the moulding, one switch per socket (so double outlets have 2 switches) and because they are part of the power outlet assembly, they add almost nothing to the cost. In fact due to switched outlets being almost universal here, a switched outlet is cheaper than an unswitched one.[this post was last edited: 6/27/2020-09:54]

 
Hi Louis

100 Hz would have been even easier... ;)

I was in primary school when Australia changed to Metric.
I was so relieved - never very good at Mathematics, I found the simplicity of metric meant I didn't have to deal with all those awkward fractions and having to remember that one of this was twelve of that, or is it sixteen?

Chris.
 
Metric IS easier

Way easier.

It was sabotaged in the US quite intentionally by forcing people to do the conversions between really difficult items such as one gallon of milk being 3.78541 litres, etc.

Interestingly, and in a very quite way, more and more YouTube creators in the US are using metric and liking it.

The US will eventually come 'round, but the opposition stems from the same place as the support for Trump.
 
When I took machining classes around 2005, it was pointed out that while the metric system made calculations somewhat easier, the American system had the benefit of being more uniform. The problem being that metric standards vary from nation to nation, from continent to continent. It might not make a big difference when buying a liter of milk, but it can make a huge difference when machining metals to within a few microns (or thousands of an inch).

 

Just sayin'.

 

 
 
"metric standards vary from nation to nation"

Not sure what makes you say that: metric standards are the same everywhere in the world because they are ISO standards that are accepted by each nation.

An A0 paper sheet is exactly the same everywhere, because there is only one ISO standard defining the size of paper sheets.
 
A few things from an Irish perspective

1. Switches on sockets. They’re used here too, but not universally. They’re not that big on the socket plate and not particularly unsightly. They basically just save you from having to plug things out to isolate them. Like I can reach down and switch off a big mess of power strips with two small switches on the wall. They’re definitely not essential, but they are convenient. They’re also not at all required by the regulations here and are purely optional.

Whether you want them or is up to you. I’d agree though. They’re a mild convenience and that’s about all. You certainly live without them, but they’re kind of useful in some ways.

The shutters on sockets being universal is definitely a safety advantage though and makes them child proof by default.

2. Size of U.K. / Irish plugs. The newer designs of moulded plugs aren’t that big, certainly compared to Schuko and most phone chargers now come with a folding (usually plastic) “ground” pin (a ground pin is required to open the socket outlet). The unfortunate bit is that for low powered, non grounded appliances, there is no such thing as a two pin plug, so everything has a plug that’s at least as bulky as 16 amp Schuko, which is a bit ludicrous.

They never really foresaw the need for plugs for very portable appliances. The standard originated in the 1940s and replaced an even bulkier system. So it’s not likely they really ever contemplated a world of electronic devices and people carrying things like laptops. They’ve definitely been slimmed down though. If you look at the plug on say an Apple mains cable, they’re about as neat as you can go with that plug design.

3. 50Hz vs 60Hz. There’s no particular logic or signifiant advantage to either. AEG and a bunch of other companies just settled on 50Hz back at the dawn of AC power. We standardised on 220V 50Hz here in Ireland before 1923. So it’s been around a long time. (The standard CENELEC and EU spec moved to 230V, to accommodate the UK which had standardised on 240V 50Hz. That has now extended to IEC recommendations, so the few others who used 240V, like Australia and NZ are included.)

4. U.K. / Ireland plugs may be enormous but the sockets are a lot neater than continental European designs that have deep recesses - Schuko/French sockets are pretty ugly looking in my opinion and even get full of dust and gunk due to the deep recess. Some French designs now incorporate a plate that covers the recess and is pushed back when the plug is inserted, giving you a flush socket when no plug is inserted, which looks far better but they’re complicated and very expensive relative to standard French sockets.

5, US plugs genuinely do lack finger protection. It’s the only place I’ve ever been accidentally shocked. I reached behind a desk and touched live pins of a partially sticking out plug. That’s impossible with modern UK, or recessed Schuko / French designs. I think there’s some risk of it in Switzerland and Italy, but only with obsolete fittings. There’s also a slight risk of it with older U.K. plugs that lacked sheathed pins but they’re fairly rare at this stage.

On the other side of it, despite their small size, NEMA plugs make a firm connection. The blades are designed to make pretty secure and solid contact.

If they added sheathed pins it would make them a very decent standard. Australia’s plugs are basically a derivative of a NEMA type with slanted pins. They’ve evolved a few extra safety features like sheathed pins, which seem to be quite a feasible addition to the NEMA 6-15 And 6-20 plugs in use.

I’d argue that US 240V plugs and sockets should probably be recessed like Schuko. There’s a fairly significant risk of shock on some of the dryer plug / stove plug designs.
 
Weird sh*t from a country that changed to metric...

A couple of funnies about going metric...

1. "clocks and calendars aren't metric but nobody has a problem with those..." Measurement of time pre-dates metric and is based in hard facts like how long it takes for the Earth to complete a lap of the Sun and how long elapses between one sunrise and the next sunrise... However a few years after Australia went metric, a TV news program did an April Fools Day news broadcast announcing that Australia was going to adopt "Metric Time" with 100 seconds to a minute and 100 minutes to an hour." (now that's fake news...)

2. Australia went metric back in 1974 but to save the building industry from having to change all its products, they used "metric-ised" terms for the existing imperial measurements - so 2 inch by 4 inch pine framing (which we call 4x2, not 2x4) was renamed 100x50 pine framing. (100mm = 4 inches.) And lengths are still in foot increments, now called 0.3 metre lengths. All these years later, the imperial terms are still used, and imperial and metric are often mixed in one sentence - "can I have 2.1 metres of 4x2 pine?" is quite normal. Plumbing is the same - you buy half inch copper pipe in six metre lengths.

3. "SI system doesn't vary but tolerances and specs do." Yes but that doesn't change for imperial vs metric. One of my favourite cars ever, the (unique to Australia) Leyland P76 of 1973 was designed by Leyland Australia to suit Australian conditions, but they were a subsidiary of British Leyland and every decision had to be signed off by head office in the UK. Leyland Australia intended to contract Karmann in Germany to manufacture the sheetmetal presses for stamping body panels, but BL in the UK insisted that their own subsidiary, Pressed Metal Corporation in the UK, got the job. PMC ignored the blueprints from Australia that specified 3/16th inch gaps between panels, and without informing the Australian subsidiary, made the presses to create panels with 5/16th inch gaps. (as was their sloppy practise in the UK.) The door seals and hinges were made locally in Australia and were designed to suit the 3/16 gaps. The cars that were manufactured had all sorts of problems such as water and dust leaks, ill-fitting panels, and hard-to-shut doors. The parent company refused to fund the press dies being remanufactured to the correct specification, so the assemblers had to create bodge solutions like fitting shims behind the hinges to align the doors better, and having new, thicker softer door seals to take up the excessive gaps. This was just bad management, not a metric or imperial issue, but I thought you might like the story.
 
"The SI System Doesn't Vary but Tolerances and Specs

Not sure what you mean.

The SI is a system of measurement units, and has nothing to do with standard or tolerances. https://www.bipm.org/en/about-us/

The ISO standards are, well, standards, and they state both the size and the tolerance to ensure compatibility worldwide. https://www.iso.org/home.html

Care to explain?
 
Look, I'm just going by what my machining instructor told us: Metric is great for calcs and international stuff, but its implementation varies from nation to nation and from continent to continent. That was about 15 years ago. Maybe it's improved since then. I would guess it's a problem with stuff like fasteners, where a bolt made in one country may or may not have a nut fit the same if the nut was made elsewhere.

 

I'd have to go back to the college and ask him for more details, or go search the internet for more info. All I can say now is that  what I was taught is that the metric system looks great in concept but in implementation it is not absolutely the uniform standard across national boundaries that it's supposed to be.
 
OK, here's an interesting discussion of Metric vs. "US Customary" systems, from Quora:

 

<span id="__w2_wEe5l32t47_link" class="photo_tooltip u-inline"><span class="ui_avatar u-flex-inline ui_avatar--large u-flex-none"> </span></span>

<span id="wEe5l32t30"><span id="wEe5l32t39"><span id="__w2_wEe5l32t40_link">Craig Weiler</span></span><span id="__w2_wEe5l32t31_cred_text" class="NameCredential">, Master Opinionator</span></span>

<span id="wEe5l32t41">Answered Jan 29, 2019</span><span class="bullet"> · </span>Author has <span class="bold_num">3.4k</span> answers and <span class="bold_num">20m</span> answer views

The metric system was not developed organically, nor did the creators let the organic system (Imperial) dictate what was needed. As a result, there are some flaws in the metric system.

The biggest flaw is that metric is base 10 instead of base 12.

10 is divisible by 2 and 5.

12 is divisible by 2,3,4 and 6, making a far superior choice for measuring.

With base 10 you basically remove the ability to work with fractions, which are better for mental field work. Base 12 is infinitely divisible: 1/2, 1/4, 1/8, 1/16, 1/32 and so on. You cannot do this in metric. Instead you run into un-intuitive strings of numbers. .5, .25, .125, .0625, .03125.

Why would this be important? It also gives you a set of ready made tolerances that are easy to follow and scale up and down quite easily. This is certainly doable in metric, it just takes a little more work.

Metric lacks two measurements that are quite useful: The inch and the foot. These have been replaced by the useless decimeter, an artifact of the base 10 system.

The foot and the inch were created because they were needed and they seamlessly fit into the yard, because it’s all base 12.

When it comes to volume measurements, base 12 is perhaps not so important, but what is important is to have a large variety of sizes to work with so that measuring is fast and easy.

For cooking Imperial offers teaspoon, tablespoon, ounce, cup, pint, quart and gallon. Metric offers liters and divisions of liters.

The Imperial system wasn’t designed to be easy to understand, it was designed to be efficient. And it is. If you check this cooking chart you’ll notice that with Imperial whatever measurement you’re using, you’ll be in single digits. 3 of this, 4 of that. It might be a bit cumbersome for a newcomer, but it’s easy to work fast and because the words don’t sound like each other it’s easier to avoid mistakes. There is very little actual measuring because there are so many sizes to choose from. If your eyes aren’t very good (Imperial was developed before eyeglasses were common.) you can make mistakes easier in metric.

Obviously most of the world does just fine with metric and it certainly isn’t a bad system by any means, but it has traded simplicity for usefulness in some situations.

 
More on the cons of the metric system (bear in mind I have a university chemistry degree so I am quite used to metric measurements. But like any system it does have its pros and cons):

 

<h3>The Cons of Metric System</h3>
1. The metric system seems logical and practical but in reality it doesn’t emerge as helpful. Rarely does one use any scale of measurement at home or even at office. Stores and manufacturers can always use scales to measure but when you have to cook or weigh something, it is not always easy to know how much is what you need. If you are slicing onions at home or making dough, how do you know how many onions you must take or how much flour you should use based on the metric system. One cannot measure 200 grams without a scale. This is a problem with other units as well, as opposed to how human scale measurements had originated such as with cup, foot or thumb.

2. The metric system is quite vast. It is a little too wide ranged for efficient use in reality. The metric system works fine when you are working on math or science in theory or on paper. It doesn’t really help that a base unit is gram and its subsequent higher unit is kilogram which is a thousand times in value. There is 1 gram which is essentially a bit of salt on your finger tip and then you have 1 kilogram which is the weight of a whole spring chicken. There is no unit in the interim. This creates a vast range. Although manufacturers and scales have made it simpler, yet there is a lot that can fall into this range and be quite perplexing.

3. The metric system has some rather quaint names or prefixes. Liters and meters are not problems but deca, deci, milli and centi are some work for the tongue. Imagine pronouncing milliliter, millimeter, centimeter, deciliter, decameter and centiliter. For those who have grown up studying the metric system and its prefixes may have gotten accustomed by now but those who have no exposure will struggle, at least initially.

4. The metric system is also criticized for being too scientific and arbitrary as a result in the real world. Consider what meter is: it is the distance traveled by light in vacuum in a time of 1⁄299,792,458 of a second. This may not be relevant for those only looking at packaging or measurements but when you need to delve deeper these complexities will come to the fore. The arbitrariness is stark when you consider time. 1 second is the base unit, 1 minute is 60 seconds, 1 decasecond is 100 seconds so it is 1 minute and 40 seconds, kilosecond is 10,000 seconds but it is not a 1,000 minutes, instead it is 2 hours 46 minutes and 40 seconds.

greengarageblog.org

7 Pros and Cons of Metric System

The metric system is used around the world with the exception of the United States and a few other countries. The metric system is being adopted in the United States and hence it is a
greengarageblog.org greengarageblog.org
 
Why the Metric System Might Be Screwed

A bit sensational, but an interesting article about the difficulty of maintaining the central standard of the metric system: the reference kilogram weight stored in Paris:

 

Hidden in a vault outside Paris, vacuum-sealed under three bell jars, sits a palm-sized metal cylinder known as the International Prototype Kilogram, or “Le Grand K.” Forged in 1879 from an alloy of platinum and iridium, it was hailed as the “perfect” kilogram—the gold standard by which other kilograms would be judged.

 

Although it’s arguably the world’s most famous weight, Le Grand K doesn’t get out much. Since hydrocarbons on fingertips or moisture in the air could contaminate its pristine surface, it goes untouched for decades, under triple lock and key at the International Bureau of Weights and Measures. Every 40 years, however, it makes an appearance. The weight is ushered from its chamber, washed with alcohol, polished, and weighed against 80 official replicas hand-delivered from laboratories around the world. Today, whenever scientists need to verify something is precisely one kilogram, they turn to one of these replicas, over which Le Grand K reigns supreme....

 

While basing measurements on tangible benchmarks was an improvement, using physical standards wasn’t without its flaws. For one, they have a nasty habit of changing. In Le Grand K’s case, it’s been losing weight. At its most recent weigh-in in 1988, it was found to be 0.05 milligrams—about the weight of a grain of sand—lighter than its underling replicas. Experts aren’t sure where this weight went, but some theorize that the replicas have been handled more often, which could subtly add weight. Others postulate Le Grand K’s alloy is “outgassing,” which means air is gradually escaping the metal.

 

Whatever the reason for Le Grand K’s gradual wasting away, it’s got scientists scrambling for a more reliable standard. Some argue that this is long overdue, since all other units of measurement are already defined by fundamental constants of nature that can be reproduced anywhere anytime (provided you’ve got some sophisticated lab equipment). The meter, for example, used to be defined by a metal rod stored alongside Le Grand K. But in 1983, it was redefined as the distance light travels in a vacuum during 1/299,792,458 of a second.

 

Standardizing the kilogram has been trickier, though. Australian scientists are polishing a one-kilogram sphere of silicon, hoping that they’ll be able to count the number of atoms it contains to create a more accurate standard. American physicists at the National Institute of Standards and Technology (NIST) are attempting to redefine a kilogram in terms of the amount of voltage required to levitate a weight. But so far, neither approach can match Le Grand K’s accuracy.

 

Why should we care whether a kilogram in a vault is “perfect” or not? Because it’s bad news when your standard is no longer standardized. While no one’s worried whether a single kilogram of apples is a hair lighter or heavier at the produce stand, a small discrepancy can become a gargantuan one if you’re dealing with, say, a whole tanker of wheat. The kilogram is also used as a building block in other measurements. The joule, for instance, is the amount of energy required to move a one-kilogram weight one meter. The candela, a measure of the brightness of light, is measured in joules per second.

 

These links mean that if the kilogram is flawed, so are the joule and candela, which could eventually cause problems in an array of industries, particularly in technology. As microchips process more information at higher speeds, even tiny deviations will lead to catastrophes. Le Grand K’s unreliability “will start to be noticeable in the next decade or two in the electronics industry,” warns NIST physicist Richard Steiner. If your next smartphone is buggy, you’ll know which hunk of metal to blame.

 

www.mentalfloss.com

Why the Metric System Might Be Screwed

The world’s most perfect weight isn’t so perfect anymore. And that has scientists scared.
www.mentalfloss.com www.mentalfloss.com
 

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