Electric 240V question?

[etrain16]

I found an image that might help anyone who is confused about how you get 240VAC in residential wiring. Here is a view of 2 opposing sine waves, representing one each of the two lines that come into your home. You can see that 120V is measured from one line to ground/neutral. 240V happens when you measure from one hot line to the other hot line, and not to ground/neutral:

 

[jbett98]

I always picture 240v as a man riding a bicycle, one leg up while the other leg is pushing down on a peddle and 120v as a one legged man on a bike working his butt off.

 

[etrain16]

I always picture 240v as a man riding a bicycle, one leg up while the other leg is pushing down on a peddle and 120v as a one legged man on a bike working his butt off.

Well, I'd like to see a picture of the 120v

 

[ZigZagZeke]

Looks very similar to what I found in a j-box under the range at my first house - except the wirenut was completely burned through - thank goodness for the metal box, or our house may have burned down. This is why I don't like AL conductors in home installs.

When I replaced the heating system in our new to us, but 40 year old house last summer with a brand new heat pump unit I had them remove the existing dual 50 amp aluminum feeds and pull in all copper conductors. I did it for this exact reason.

 

[ZigZagZeke]

Agreed, and I would add this - a 277v single conductor (off a 277/480 wye system), will cause you to clamp down and not be able to let go. I had it happen to a fellow electrician years ago - he grabbed a steel stud to steady himself on an 8' ladder and a loose 277v wire was in contact with the stud - he couldn't let go, and he was alone, only had the presence of mind to jump from the ladder to break himself loose. Messed his heart up for days after that. Nasty stuff that electricity - them folks that work with it must be a special kind of crazy - not Hillary crazy, but crazy.

One of our electricians was rewiring a 4160 volt pump motor (about 200 hp) while a co-worker was finishing up its twin 30 feet away. The first electrician reported off that job to his foreman when he was done. The foreman mistakenly ordered the breaker for the wrong pump racked in for testing. The only thing that saved the life of the guy still working was that the operator who racked in the breaker racked in the wrong one, cancelling the foreman's mistake.