120/240 and 120/208 Volt Transformer Secondaries 

This man is a master at teaching... so clear. his body movements, his eye movements , hands all work in coordination with each other. his voice, easy on the ears... His brain the conductor of the whole operation. A pleasure to learn from...Thank you Dave.

Truly a master in explaining, makes it easier to understand the concepts

I am electromechanical engineer, your explanation is very very clear. THANKS a lot teacher.

This man is really good he knows how to explain.He is a master keep it up

As a EE, I have to commend you on a well diagrammed and spoken lesson. Good job!

i feel lucky that people like dave are on youtube and shares their knowledge, great info!

Thank you, as a mechanical engineer I’ve always struggled with electrical concepts and this helped me understand much more about how the different windings affect voltage.

I was so lucky to be in his classes. Dave, you rock, man.

Nice work Dave. This is one of the most thorough and understandable descriptions on 120/240 and 120/208....excellent.

Dave your videos are so immensely understated. You're an absolute hidden gem and I can't thank you enough for making this material available. I'm an IBEW electrician apprentice in my 3rd year and I constantly supplement my school work with your videos.

You have simplified months of frustration in trying to understand these concepts. I cannot wait to check out the rest of your videos. I so appreciate the clarity you deliver. THANK YOU!

This is one of the best videos I have watched out of a lot out there that explains with this much clarity and expertise. Thanks for passing your knowledge how it should be with all.

This man is a truly gifted teacher!!!!

Other than you kept referring to the peak voltages as 120V which would be confusing to a beginner when actually Vp ≈ 170Vac or Vp-p ≈ 340Vac hence the need for capacitors with 370V or 440V ratings. Root Mean Square is just the DC equivalent hence there would be a straight line drawn through the sine wave to represent that average. Vrms = Vpeak/√(2). RMS is the only way to average a sine wave in case your wondering. It's also used to take an average in statistics to minimum the effects of outliers 😉 - 1st drawing - Single Phase - 2nd drawing - Three Phase (Wye) - 3rd drawing - Three Phase (Delta) I suggest adding "Ugly's Electrical References" book to your toolbox because it covers all this and much more in case you forget. Great video 😊

Dave, I was looking for the definition of a great teacher, and now I got it on this RU-vid video. You are beyond excellent and keep up doing this amazing teaching style.

Thank you, Dave! I've just discovered your videos while looking for some information about transformers. You combine two of my favorite subjects: electricity and math. Fifty years ago I was an electrician in the Navy. At that time, we were trained in single phase and three-phase delta and wye transformers. I understood it completely at the time, but never had experience with them since then and lost my knowledge of them. Now I understand them a whole lot better.

Seriously, this guy has mastered the description of *why* 208v.

Sir, you're a teaching machine! You managed to master all your techniques magnificently. Thank you for that

The clearest instruction / explanation I have ever seen on this. Great video

Wow I wish I had a teacher like you when I was in trade school, nice job explaining and simplify something so complicated, please continue uploading videos!!!

Searched for this explanation for way too long. Very well done Dave.

this is literally the best explanation ive ever heard for this.

I'm blown away by your efficiency sir! All the little comments added explaining things for our green compadres shows how masterfully you teach. Thank you sir.

I liked this guy the moment he spoke. You can tell a great teacher within seconds. God bless S.T.E.M.

I've been digging to find a good explanation and now I've found it. Thank you sir!

Glad to hear someone use the correct definition of voltage. It is the "difference of potential" between two points.

Thank You Dave well done! Best teacher I seen yet! Thanks again.

THANK YOU, I APPRECIATE YOU. Im literally sending this to few of my classmates and couple of my electrical friends

I'm about to start my second year of school and man am I glad I stumbled on your videos

Dude. This is awesome. Great way of explaining it. I totally get how this works, but being able to explain it is very hard for me and this way of explaining it is perfect.

Great teaching skills. You making it very easy to follow. Thank You 🙏🏼

Excellent video that explained some of the lingering questions I had regarding electrotechnology. Thankyou Dave!

Best explanation ever. I finally understand!!!!!!!!!! Thank you.

This is the best explanation I have ever seen.

Great people share their knowledge!!! God bless you!

The 120/240V thing was actually a late 19th century thing - all derived from the Great Fire of Chicago. Edison lamps were made out of carbon, and used 110V, however, other companies figured out how to make lamps using tungsten, a much more resilient metal and could work at 240V (carbon lamps burn up at 240V). Since adoption of electricity was much slower in Europe, the European utilities went with 240V as it saved money on copper and is more efficient. Our 110V system was derived as a split-phase system, because Edison noticed that some people's lights were brighter than others. So he designed the system as two 110V generators (this was DC, mind you) and connected them together to form a third neutral line. He realized by monitoring the current flowing on the neutral line, he could determine how bad the imbalance was and rebalance the grid so the same number of lamps were on each half so everyone's lights were the same brightness. In addition, if you needed more power, you had 240V (DC) available. Now, electrification was huge in the US - especially after the Great Fire of Chicago which meant everyone started from scratch, and skyscrapers were a thing. Gas lamps couldn't be lit more than a few stories up, and everyone wanted electric lighting. So much so that demand for light builbs was so big even though carbon lamps were obsolete, Edison was still making millions of them as the tungsten lamp makers couldn't keep up (in the late 19th century, they made around 10 million tungsten lamps, and Edison made nearly 60M carbon lamps. This changed about 20 years later in the early 20th century when carbon lamps were finally obsolete and replaced with tungsten lamps. However, by now the die has been cast - 110V had been around for so long, there was no appetite to change over to 240V.. In Europe, electric lamps were seen as a novelty, and very few people had it. The rich folks refused to install it in their castles, so when it came time, it was trivial to switch over. Oh, and the first war of the currents was between Edison and Westinghouse, not Tesla. The second war of the currents was between GE and Westinghouse which dictated if we'd use two-phase (Westinghouse, via Tesla's patents) or three-phase (GE, Edison had been kicked out) AC. Tesla is confused in these because Westinghouse bought Tesla's AC motor patent (and later all of Tesla's patents). That patent showed how a motor would work at 60Hz two-phase. You have to remember though, that just because of this, power was still not quite standardized as you could get DC, 60Hz, or 133Hz AC power (133Hz because Westinghouse managed to find a design for an electric meter but that required 133Hz to run properly).

Fantastic video! I recently took over management of a 160 year old theatre that has a high leg delta panel in the projection room. Wanted to get familiar with the system. This video was incredible informative. Don't be worried. It did not give me the the confidence to monkey with the panel. I'll call a pro anytime this panel needs works.

Very good explanation. Crystal clear tome

Amazing explanation! I like the way you teach this topic. Thanks for sharing knowledge.

Wonderful info, thoughtfully and clearly laid out

Wow you are amazing! Thank you so much for making this video. I will share this to all my friends.

Amazing explanation, very good job 👏

30, 60, 90 degrees and you get 208. Wow, I never realized that trigonometry and electricity were connected!

Thank you Dave, easily explains the differences as well as applications. And thank you for the math lesson (brings back memories).

Thanks from Austria for the teaching - work. 🙏

You are way better than any professor I know. I graduated with EE from college also.

Very good explanation/tutorial. Thank you for sharing.

Excellent teacher! That was great explanation, made it look so simple even though it ain’t. 👍👍👍

what a master class. an absolute pleasure to see it

Excellent presentation Dave, was a joy to learn from ya

Thank you for a additional knowledge it's very important specially in my daily operations. Electrical lineman here in the phillipunes thanks a lot.

Absolutely immaculate explanation

Wow, this was super helpful. Thanks for posting this.

fantastic job explaining this topic

Very Informative! Easy to follow!

Thank you so much for your crispy clear explanation! This helped me so much, awesome!

Clearly explained. Really helped what i was looking for

I like the idea of the radius of a circle in terms of a generator, starting from west or zero axis , like a radar from west , north , east , south and to west. ! Radar or radius is from center point to the inner circumference of the circle ⭕️ . Diameter is from west to east or north to south, that is why a radius really is interesting like radar !

Awesome job of explaining 120/240 and 120/208 theory 👍

"Hot water heater". (snicker, chortle, guffaw). Perfect lesson, yet again.

Well done. And I actually saw the fireworks first hand at work when one of the guys installed a bunch of new 120 V fluorescent fixtures to a 208V high leg by mistake. WE also had 277 VOLT stuff that people made mistakes with. Luckily we worked for BIG OIL. They could afford it.

You're a very good teacher. I've been trying to find someone to explain this to me for awhile now, searching all over RU-vid and the internet in general and haven't found a single person that can explain this in a manner that I could understand until I seen this video. I appreciate that you took the time to make this. Thank you.

Your the best thanks so much for simplifying this process.

Good info, thanks for putting this out here for people to learn from.

Another EE here, and I like your teaching style, you dive just deep enough into the theory for the non-mathematically inclined to still understand the important concepts. It would be so easy to try and "prove" that you know the theory, but at the risk and expense of losing your audience, and that makes a poor instructor! You make it easy for those just beginning to learn the electrical trade to understand. Nice work!

My favorite term for the high leg of a delta transformer for 120/240 is the "bastard leg."

Truly outstanding lesson. Thank you.

Amazing explanation. Thank you!

Awesome job explaining

My God I needed this refreshing course I'm am definitely enlightened

Your explanations are clear

Excellent explanation

This is some high-quality content here! Thank you so much for making this video! It is extremely helpful.

Great teacher. Awesome job

Thank you for excellent lesson

Good teacher. Love it!!

This was excellent. Thank you!

Excellent instruction, and a perfect example of how clarity doesn't require fancy animation, just a clear grasp of subject, words, and pictures. Now for the love of all that's decent and proper, stop saying _"hot_ water heater", and change that "HW" to "WH". You don't need to heat hot water.

Amazing video and explanation

Excellent class!!!!

Excellent video!!!! For the case of the delta transformer. As we can determine the current in each winding to determine the single-phase and three-phase load distribution in them and thus their optimal size, this in the case of being a bank of transformers.

Amazing instruction.

This should have more people watching

Subscribed! love your videos

Very good work there

Awsome video, really enjoyed it

Excellent video!

Great video, very clear..thanks!

Good explaining picture worth 1000 word finally understand grounded from grounding

Thank you! Really gonna help me with school

Thank you for helping me understand the wye out of phase 208 and the delta ! My teacher could use some lessons from you on explaining things better!

Great video sir

Thanks! great Video!

Beautiful

Clear and enjoyable!

Great video

Big help!! Thank you!

Amazing content and speak ability.

Thank you very much!

Thank you