Weak Arc on Lincoln 225 ac

[JimRB]

I dont know a lot about electricity but my 3 prong welding plug has 2- 110v that if you check each lead to the ground you get 110 on each leg so I always assumed that both 110v legs went back thru the ground lug to complete the circuit.

It is important to know that the ground connection on an electrical circuit is to protect you, the equipment sort of and the premise electrical wiring. It is to supply an easy and low resistance circuit back to the panel box to allow the circuit breaker to pop open when there is a dangerous short. In modern wiring it is not to make a 120v circuit. Measuring 220-240 volts is measured hot leg to hot leg. Or measuring a 208v three phase circuit it is hot leg to hot leg and 120v is checked using the white wire/neutral. Yes you can cheat and measure hot leg to ground but that is not quite the same as hot leg to neutral. OK, ignore me as I am not an electrician. Do note that old dryer circuits were 3 wire. Current code has them at 4 wires. I think the same situation for a range circuit now has to be 4 wire. You can do a duckduckgo search to hear from real electricians on this concept.

 

[Industrial Toys]

We have had this argument before. They are not out of phase. They are simply different taps (different potential) off a single phase transformer. No such thing as two phase household service. Saying that the two 120 legs are in different phase, would suggest some kind of two phase service.

Anyone who needs to understand household 120/240 service should investigate how a transformer works.

Think of it as with DC and batteries. You have four 6 volt batteries in series. Gives you 48 volts. Now you connect the center connection between two batteries to ground. Now you will get 24 volts to ground from the farthest battery one way and the sme from the farthest battery the other way, AND 48 volts between the two. This is EXACTLY the arrangment with the transformer feeding your house. Center tap goes to neutral/ground. Nothing at all about phase! It's about voltage/potential off the transformer windings.

 

[BukitCase]

Jim, you posted while I was typing; retired now, after decades in electronics and the last 33 years in heavy industry instrumentation and control - State of Oregon requires TWO electrical licenses for this, a "Restricted Energy" for low voltage, and at least a "LME" (Limited Maintenance Electrician) - Same tests for both, IMO it's more for "revenue enhancement" than anything... Steve

Edit - IT, I did NOT say TWO phase; but the two "taps" on the CENTER TAPPED secondary of the residential feed side of the transformer, are DEFINITELY "out of phase" with each other; sync a scope to ONE and probe BOTH, one leg will be at its POSITIVE peak while the OTHER leg is at its NEGATIVE peak.

And yes, you're correct in calling it single phase, but for explanation purposes it tends to get the point across about why you can't pick just ANY two "hots" and expect 240 volts...

BTW, 4 6 volt batteries in series gives you 24 volts; (sorry, couldn't resist :=)

 

[Industrial Toys]

If phase simply means a time relationship, how do you get time shifting on a transformer? All windings and any taps rise and fall in potential at the same time (but at varyng potential to each other) with the one and only AC sine (single phase) wave feeding the thing.

 

[BukitCase]

Technically, the correct term is as you said; the two "hots" in a residential feed are "out of POLARITY", due to being derived from opposite ends of a center-tapped SINGLE PHASE transformer. Optically (on a scope) the two such 120 volt feeds APPEAR to be out of phase (which is why SOME people grasp the concept better with that explanation) - but in reality, the two hots are just two halves of a single phase. Since they ARE both derived from a single phase SOURCE, they can (as you mentioned) NEVER be truly out of phase (like the legs of a 3 phase source @ 120 degrees) - so the term "opposite polarity" would be the more correct one.

I don't think we actually disagree, but I spent 3 of my 4 years in the military TEACHING electronics theory and repair; my job was to take cooks, truck drivers, etc, and turn 'em into technicians. I got used to using ANYTHING the student understood to explain stuff he'd never seen before. Guess old habits die hard, that job was over in 1970... Steve

 

[jaxs]

I thought his thread had run it's course and died but :cool2: now we go to the tall wall for electrical debate. :applause: I have my popcorn,carry on.

 

[Industrial Toys]

Has nothing to do with polarity, but potential. Yes comparing AC to DC is dangerous, but for this discussion, works perfectly.

To further demonstrat my point, you could have a 240 volt transformer (like is feeding your house) and decide to tap it to ground/neutral at some other point. Say 40 volts one way 200 the other. You would still have 240 across both, but 40 to ground one way and 200 to ground the other. Still nothing to do with phase. Nothing at all. Just potential differences.

You can have a transformer with all kinds of taps at different voltages and you will read varying voltages depending on how they are connected. Again, all about potential. Nothing about phase.

EDIT: Trying to be yet even clearer. Any transformer will have all wiring, all coils and taps (and of course the magnetic field) rising and falling in unison to the AC sinewave. Nothing shifting phase within.

 

[dragoneggs]

I'm so glad I am a mechanical engineer.

 

[GSVette]

I'm so glad I am a mechanical engineer.

There’s a reason why we had the electrical engineering students on the other side of the campus with the physics majors!!

 

[WranglerX]

It sometimes seem's long distance diagnostics is becoming a lost art. There's no shortage of nice folks but it's rare seeing one like Old over on YT. He answers 8 or 10 complex questions daily without even breaking a sweat. I've tried but concentrating hard enough to see problems long distance make's my noggin hurt. :laughing:

Many times it takes a lot of forum interaction to get problem corrected because of misdiagnosis by OP with problem and poorly worded question... Usually find it takes a bit of back and forth maybe 6-8 or 10 or "X" responses to get all the information needed be able to diagnose the problem correctly.... Writing for clarity, and lack of knowledge about subject (tractor?) and reading for comprehension seems to be a lost art in this computer age.... And spell check can be you worst enemy...

Many a time I have been accused of bein condescending or sarcastic when I am only trying to extract enough information to analyze situation or trying to express an answer and person on other end gets butt hurt because they feel I am talking down to them, when they should only be reading the text for the information/data it contains, putting emotion and feeling aside and just respond to what is provided.... Guess this is why I am not a good author or wordsmith.... And many a time saying the same thing face to face with the spoken word does not get the same adverse reaction it does to text... Go figure...

Then there is the guy who gets all reactionary about the "correct" solution to the problem BUT it is the solution or answer he did not want to hear....

Dale