# Units of measurement

#### Besoeker

##### Senior Member
I know I have brought this topic up before.
Will the US ever join the rest of the world and move to using SI units of measure?
For example, is there any sense in two different units for power?

And AWG is baffling in its derivation.

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

#### junkhound

##### Senior Member
Most US engineers are bi-dimensional, I even think in metric in other than mechanical construction.

Perhaps we should all go back to Megalithic yards.

Wonder what electrical units would look like in Megalithic terms ? Other than any precursors of Bagdad battery, no archeological artifacts though

#### Besoeker

##### Senior Member
Most US engineers are bi-dimensional, I even think in metric in other than mechanical construction.
It's SI though. Metric refers to metres, a unit of length. Hw many metres in a kilogram?......

#### ggunn

##### PE (Electrical), NABCEP certified
I know I have brought this topic up before.
Will the US ever join the rest of the world and move to using SI units of measure?
Of course not, but you knew that, right? There was a bit of a push back in the 70's to "go metric" here but it stalled out and went away.

#### mivey

##### Senior Member
Will the US ever join the rest of the world and move to using SI units of measure?
Probably when we get to the point we really care or when we value the opinions of others more than our own.

#### ggunn

##### PE (Electrical), NABCEP certified
Probably when we get to the point we really care or when we value the opinions of others more than our own.
Or when we get to the point where everyone has to routinely divide seven feet eleven and seventeen thirty-seconds inches by five.

#### Besoeker

##### Senior Member
Probably when we get to the point we really care or when we value the opinions of others more than our own.
Opinions? It's a matter of ease of use. You don't need HP and kW or the need for their conversion factors. Motor power becomes P = Tω. Forget the 33,000 ft-lbs per minute or the 550 ft-lbs per second.
You wouldn't need yards, and feet and inches and miles and leagues. You'd just have the metre with multiples and sub multiples of it.
You'd measure wire in mm^2 which is it's actual cross sectional area.
Recipes wouldn't need pounds an ounces.............the list goes on.

Just so much simpler. and that's the opinion from one who grew up with Imperial measure, then CGS, then MKS. and lastly SI.
Unlike my father, I don't need to know about the bushel or peck.

##### Senior Member
I for one wish it was taken up by at least the NEC... I mean, so many countries have adopted the NEC but yet have the wires in Metric. Jamaica will be adopting it but their wires are Metric... and I know 2.5mm is not 12 gauge..

#### MAC702

##### Senior Member
It's already in the NEC, but stupidly done. We use easy rounded nominals (Trade Size) for Imperial measurements, but not for metric ones.

A 1/2 conduit is more like 5/8 (and varies with wall thickness), but we are all okay with using the nice rounded, easy to remember sequences: 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 3-1/2, 4, 5, and 6. The "inch" unit marker purposely left off.

But in metric, screw the easy ROUNDED OFF sequence, and use this Metric Designator instead: 16, 21, 27, 35, 41, 53, 63, 78, 91, 103, 129, and 155.

We ALREADY use a gross rounding in Imperial. There's no reason why the Metric Designations shouldn't be: 15, 20, 25, 35, 40, 55, 65, 80, 90, 130, and 155; or something like that. Maybe even getting rid of the 5's after 35.

#### K8MHZ

##### Senior Member
Opinions? It's a matter of ease of use. You don't need HP and kW or the need for their conversion factors. Motor power becomes P = Tω. Forget the 33,000 ft-lbs per minute or the 550 ft-lbs per second.
You wouldn't need yards, and feet and inches and miles and leagues. You'd just have the metre with multiples and sub multiples of it.
You'd measure wire in mm^2 which is it's actual cross sectional area.
Recipes wouldn't need pounds an ounces.............the list goes on.

Just so much simpler. and that's the opinion from one who grew up with Imperial measure, then CGS, then MKS. and lastly SI.
Unlike my father, I don't need to know about the bushel or peck.
I am with you on this and have been for decades, but my vote just doesn't matter.

The fact is that people, at least Americans, simply don't like change and the SI system is outside their comfort zone, even if it's easier to use. I was exposed to it when I was a mere teen and was racing motorcycles. I was familiar with the metric system because of that and had no problem using it. I DID have a problem later in life when US automakers switched over and some of the cars I worked on were metric, while others were in inches. That required two sets of tools for every part.

I still get a chuckle about tire sizes that are in both metric and inches on the same tire. What is the deal with that???

And the US isn't the Lone Ranger. Doesn't the UK still express fuel economy in miles per gallon? Or is that just Canada?

##### Senior Member
which does not fit when you go to buy products in Europe or the Caribbean... go try to buy 3/4 inch conduit, and 12 guage wire... they will give you 2.5mm wire and 20mm pipe usually... but sometimes will sell you 25mm pipe instead...
You might be better off with 4mm wire as well...but that is not actually 10 guage wire... lol so amps dont work, etc and so forth...

So you try to use the BS 7671 tables for 120 volt systems...not easy either, but easier, and there is a formula in the Onsite Guide that tells you how to convert some things for 120 instead of the table values for 230..lol...

#### MAC702

##### Senior Member
My father is vehemently against it, but Metric doesn't bother me. I just want ONE or the OTHER. It's retarded that mechanics and anyone with tools needs two sets of every kind of wrench and socket set.

But the Brits have to admit they haven't changed fully either, and love their traditional units. Isn't it illegal to sell beer except by the pint, or is that an urban myth that refuses to die?

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##### Senior Member
And the US isn't the Lone Ranger. Doesn't the UK still express fuel economy in miles per gallon? Or is that just Canada?
Well, when I go to Jamaica or France I drive in Kilometers per hour and using Kilometers to places, but in England I use miles... however, in a way it makes sense because it is Imperial measurements... and the Queen is still in charge of the empire!

#### Besoeker

##### Senior Member
To answer a few questions here.
It isn't metric, that is based on the metre, a unit of length. But it is a common misnomer used here too. It's SI.
Yes, we still buy beer in pints in a pub but wine in ml. In a grocery store beer cans are typically 330, 440, 500, or 568 ml, the last being an Imperial pint.
Yes, we still use MPG for fuel consumption but then our road signs are all in miles. Most cars, maybe all now, have speedometers in MPH and KPH. Speed limits are in MPH.

Ask the man in the street their height and most likely they will give you in feet and inches. Their weight in stones (14lb) and pounds. Go for a medical and it is done in metres and kg.

Yes, still a bit of a muddle on some things but, in engineering, it is all SI.

#### Little Bill

##### Moderator
Staff member
To answer a few questions here.
It isn't metric, that is based on the metre, a unit of length. But it is a common misnomer used here too. It's SI.
Yes, we still buy beer in pints in a pub but wine in ml. In a grocery store beer cans are typically 330, 440, 500, or 568 ml, the last being an Imperial pint.
Yes, we still use MPG for fuel consumption but then our road signs are all in miles. Most cars, maybe all now, have speedometers in MPH and KPH. Speed limits are in MPH.

Ask the man in the street their height and most likely they will give you in feet and inches. Their weight in stones (14lb) and pounds. Go for a medical and it is done in metres and kg.

Yes, still a bit of a muddle on some things but, in engineering, it is all SI.
You're the only person I know that calls it "SI" so please tell me/us what does "SI" stand for?

#### Besoeker

##### Senior Member
You're the only person I know that calls it "SI" so please tell me/us what does "SI" stand for?
Système international.

#### tom baker

##### First Chief Moderator
Staff member
One advantage of legal marijuana is having to know the metric system...
I agree metric units are much easier to work with, where I work all our lab work is metric, as most places are.
But with metric its all or nothing, which is why our previous attempts in the US have failed.

#### StarCat

##### Industrial Engineering Tech
Metrics

Metrics

I know I have brought this topic up before.
Will the US ever join the rest of the world and move to using SI units of measure?
For example, is there any sense in two different units for power?

And AWG is baffling in its derivation.

https://en.wikipedia.org/wiki/American_wire_gauge
There is high sense in a " People " using a system that works for them and that they are comfortable with, as opposed to having another system forced on them by external authority figures.
Metrics are one of the worst ideas that ever was. Even Napolean while in exile saw this simple fact.
Metrics are a system based on false abstractions of the Earth, as thus they are not harmonic. Anything constructed to metric dimensions will both look and feel wrong to the sensitive person.
Celsius is useless for HVACR work, and problematic. Bar is the worst of all and totally useless.Seeing Mollier diagrams written in Bar is a complete joke.
There is nothing worse that having to deal with watts when Horsepower is " whats needed." A large volume of current documentation has become near impossible to decrypt.
The rest of the world is wrong and the USA is correct and the Metric system should be opposed and removed from as many localities as have the sanity to do so.
Metrics are fully infuriating and were only of very limited use in the Chemistry lab. If you go digging into other areas of analytics, it will be discovered that there are many problems with many of the units of mesure, and they in fact cannot be used helpfully at all for some types of work.
I will not speak to people in metric terms nor will I allow metrics loose in my shop.

#### Besoeker

##### Senior Member
There is high sense in a " People " using a system that works for them and that they are comfortable with, as opposed to having another system forced on them by external authority figures.
Metrics are one of the worst ideas that ever was. Even Napolean while in exile saw this simple fact.
Metrics are a system based on false abstractions of the Earth, as thus they are not harmonic. Anything constructed to metric dimensions will both look and feel wrong to the sensitive person.
Celsius is useless for HVACR work, and problematic. Bar is the worst of all and totally useless.Seeing Mollier diagrams written in Bar is a complete joke.
There is nothing worse that having to deal with watts when Horsepower is " whats needed." A large volume of current documentation has become near impossible to decrypt.
The rest of the world is wrong and the USA is correct and the Metric system should be opposed and removed from as many localities as have the sanity to do so.
Metrics are fully infuriating and were only of very limited use in the Chemistry lab. If you go digging into other areas of analytics, it will be discovered that there are many problems with many of the units of mesure, and they in fact cannot be used helpfully at all for some types of work.
I will not speak to people in metric terms nor will I allow metrics loose in my shop.
So we should resurrect the cubit? Would that make you happy?
Or maybe rods, poles, and perches?

#### MAC702

##### Senior Member
The word metric is for measurement, not specifically length. I always assumed the meter comes from the metric system, not vice versa. Yes, it's the modern International System, or SI, also, but it's not wrong to call it the metric system. EVERYONE knows what it means.

When we talk about the metrics of a baseball pitcher, or anything, we aren't referring to measurements of length usually.