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Hi there. So, as I mentioned in my intro, I’m in my second year of apprenticeship. I’ve accumulated a pretty convoluted list of formulas, which I try to keep track of in a small spiral notebook. Not just Ohm’s law (which I remember with the EIR and PIE acronyms anyway) but also three-phase transformer calculations, inductance, etc.

So, I’m wondering, is there a go-to reference book or website that has these formulas and calculations organized in one place for electricians? I tried to google it and pulled up mostly engineering resources, which I suspect is way beyond what I’ll be asked to do on the job.

Many thanks for any help in this.
 

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Ugly's...

Available at every supply house.

An apprentice can't learn from a smart phone app.

Ugly's has already compiled all of the tables that you will constantly refer to as an electrician.
 

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I seem to remember years back you could get several different types of "slide rule" type manual calculators that either worked some of this stuff out or had formula printed on the back as info..

I think you could even get them for calculating bends in conduit???

I've not seen stuff like this in a while as its all done by apps these days, but I am old enough to value stuff that does not rely on batteries or wifi/phone service...
 

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I seem to remember years back you could get several different types of "slide rule" type manual calculators that either worked some of this stuff out or had formula printed on the back as info..

I think you could even get them for calculating bends in conduit???

I've not seen stuff like this in a while as its all done by apps these days, but I am old enough to value stuff that does not rely on batteries or wifi/phone service...
Yeah, those cardboard slide rule things used to be regular supply house freebies for almost everything imaginable. Haven't seen one given out for anything in years and years. "There's an app for that" these days. The one I keep around is the overload heater selector for A-B motor starters. It's about the only one I still find useful.
 

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Yeah, those cardboard slide rule things used to be regular supply house freebies for almost everything imaginable. Haven't seen one given out for anything in years and years. "There's an app for that" these days. The one I keep around is the overload heater selector for A-B motor starters. It's about the only one I still find useful.
I seem to recall being taught how to use a proper slide rule in school at one point; using one would be a real novelty to day!
 

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I seem to recall being taught how to use a proper slide rule in school at one point; using one would be a real novelty to day!
I went to a steam show over the summer and one of the machinists there had a slide rule in a leather holster on his belt. :glasses: Must have been to impress the ladies.
 

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I seem to recall being taught how to use a proper slide rule in school at one point; using one would be a real novelty to day!
Just curious, about what year would that have been?

It seems like the last these were taught in the US was the early 70's, before my time (but not by much).

I got one and learned how to use it just out of curiosity a couple years ago, very interesting gadget. They were arguably more important than the computer in putting men on the moon.
 

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Just curious, about what year would that have been?

It seems like the last these were taught in the US was the early 70's, before my time (but not by much).

I got one and learned how to use it just out of curiosity a couple years ago, very interesting gadget. They were arguably more important than the computer in putting men on the moon.
I was trying to remember that as well..I think it was in what you guys term High School so it would have been the early 80's...I definitely remember in Math we had to use Trig tables ref book for things like finding values of sine and co-sine ect and I think we used the slide rule about then as weil. A little later we were permitted to use calculators, but I recall that was only after we had learned the "old ways"...
 

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My high school trig and calc teacher (same guy) used one all the time and would show anyone that wanted to learn, but it wasn't a requirement. We just used calculators. Very often, he was faster with a slide rule than we were with a calculator. Probably one of my regrets is having not learned how to use one, at least. What, with the upcoming zombie apocolypse and all.
 
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Started in 68 and went to school in January, February for the next 4 years. So for sure '69 and 70 used the slide thingy.

We had a giant one in the class hanging from the ceiling that the instructor would use. I'm thinking 20 feet long :surprise:. Well maybe 8 feet.

I think 3rd year I bought a neon lit up calc, ran on a 9 volt battery that didn't last too long. Maybe 8 digits.

Have no idea how to run a slide rule now and haven't seen one for 40 years or so.
 

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Hackenschmidt
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My high school trig and calc teacher (same guy) used one all the time and would show anyone that wanted to learn, but it wasn't a requirement. We just used calculators. Very often, he was faster with a slide rule than we were with a calculator. Probably one of my regrets is having not learned how to use one, at least. What, with the upcoming zombie apocolypse and all.
As far as I could see the slide rule was just lookup table for trig values converted to a slider, nothing too clever.

The slide rule is based on logarithms. You can imagine a slide rule type device to do addition would be pretty simple. Well, a slide rule uses a log scale that same way to convert multiplication and division to addition and subtraction.

The real power of the slide rule is it lets you do multiplication and division quickly to a few significant digits of accuracy. With a pocket sized slide rule you're going to have 3 digits of accuracy. There were special gadgets made to make greater accuracy possible without making the slide rule gigantic.

It's not something that you'd use for accounting where you need to-the-penny accuracy, it's for engineering where accuracy to a certain level of precision is adequate.

It is not hard to learn to do multiplication and division with a slide rule, you could learn it in less than an hour, maybe even much less if you're mathematically inclined.
 

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Started in 68 and went to school in January, February for the next 4 years. So for sure '69 and 70 used the slide thingy.

We had a giant one in the class hanging from the ceiling that the instructor would use. I'm thinking 20 feet long :surprise:. Well maybe 8 feet.

I think 3rd year I bought a neon lit up calc, ran on a 9 volt battery that didn't last too long. Maybe 8 digits.

Have no idea how to run a slide rule now and haven't seen one for 40 years or so.
When I read up on this, the slide rule was a big deal for centuries. Calculators were invented in the 60's and went from the price of an entry level automobile to less than what a slide rule cost in about ten years.

Slide rules were not cheap, they were precision instruments and not all that easy to manufacture. Once the pocket calculator was cheaper, the slide rule promptly vanished from public education here.

I have read stories about engineers in the 70s not quite trusting these new calculator gadgets and checking their answers with their slide rules :)

You could make the case for the value of learning the device as part of the educational process because it does involve some understanding which imparts benefits deeper than just arriving at the solution to your calculation.
 

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It was killing me, so I just googled 'most popular slide rule brand' and got Pickett, and then I checked their most popular model, and it's 120. So I went on eBay for 12 bucks and ordered me one. It seems to be the defacto student model that was used in schools for years from the 2 minutes of research.
 

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It was killing me, so I just googled 'most popular slide rule brand' and got Pickett, and then I checked their most popular model, and it's 120. So I went on eBay for 12 bucks and ordered me one. It seems to be the defacto student model that was used in schools for years from the 2 minutes of research.
Hope you got the leather belt pouch for it!
 

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It's not a handy single reference book, but for a solid understanding of most things electrical, get the Hawkins Electrical Guides. You will learn more from them than any other reference I've seen.
 
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