3-Phase Explained ( Commerical Electrical )

lol…I know…in fact when I looked up MY house it was not even their…I built my house in 2001 and the image to the area where my house it was a big field…lol…ahhh it bought me back to the first day i walked the field and said…this is where my house will be…lol

Ahhh…yes…thank goodness for the NEW transformers that reside in K factors…lol…build to handle the oncoming harmonics factors…you see…they are learning more and more about them every day.

You guys are GOOD…you have sized it to meet any possible need…man I need you down here so I can build my commerical side of the business bigger…lol…good people are hard to find.

The power a modern office / research building uses is staggering.

We did a building for a pharmaceutical company the service was 13.8 KV and would often draw 150 amps.

Thats about 3500 KW or in house service terms (240 volt single phase) about 14,000 amps!

Well thanks we do have some great guys but we also work on well engineerd projects.

Have to give the engineers their due.

But we can ‘wing’ it, the plans I was handed for the 3000 amp serice change with the large transfomer where a simple one line riser diagram quickly drawn by the project manger on one 8.5 x 11 sheet of paper. I had to figure the pipe, wire and layout.

Thats the part of the business end up doing and takes much of my time. Many of the commerical jobs do not want to pay the engineers to do the electrical calculations for these type of things anymore…figure they can cut that cost out and except the electrical contractor to do it…

Happening more and more…and in commercial jobs these days I get tired of playing electrician and electrical engineer as well…I like commercial plans that are already layed out and the electrician just follows the plan…sad to say getting less and less of those detailed plans…“SIGH”…the good news is I am doing less and less commercial jobs…YAAHHHOOO

For some reason Naples Fla has a lot of red leg delta. It will throw you if it is the first time you see it. We were having a lot of problems with some equiplment there until I figured out it was wired 208 wye.


Yeah…no doubt…

Back years ago they would put the high leg on the C connection and over years moved it to the B connection…and as the time went on the new panels are added and it still has a old system at the transformer under control of PACO…then the electrician ( new one ) replaced the panel schedule and then follows todays requirements for placement and marking and well…next thing you know…everything that is on the center line is BLOWN…all because of a change from the high leg position in the years before they started standardizing it…see that alot in older 3 phase construction that is being updated to newer.

Yah…I always tell the young electricians to always test line to line in a secondary panel…line to ground should read 120V but line to line should read 208V in a normal WYE setup.

Same as in a delta…test from the B line to the C line which is normally the 120V phase line…it should give you 208V which means it is a Delta with a high leg…but any line to line will be 240V.

Anyway…as I am sure you do as well…we see it all the time and if you have no basics in 3-phase it can get confusing for someone new in the industry.

We got in trouble because nobody at IBM had ever seen delta. The plugs were the same and everything powered up normally. A lot of the stuff really didn’t care. We did have tape drive controllers with ferro supplies and they were burning up. I got involved on #2 or #3.
The funny thing was some of the equipment was plugged for 240 so somebody must have noticed. It just wasn’t everyone who worked there. This was a customer who bought used equipment so it could have come in plugged that way.