# Watch for the high leg !



## mollydog (Jan 9, 2009)

Just last night I had a call from a good friend who is a top notch electrician, his work is textbook perfect, but his experience in three phase commercial services got em last night. He called in a panic, he had replaced a feeder from first floor to second, when he closed the 100 feeder breaker, lights were buzzing and it seems he just turned off all the lights and went home, but the owner come in to sweep and blew up an 1100 dollar sweeper. so I got there and before I walked in I knew he tapped a hot leg, well I was right... The panel he fed from was not identified like it is supposed to be (center & orangish in color) I dont know if he didnt know or just assumed it was 120/208..... the open space every other third phase should have caught his attention... My point is "Make sure you check" this time he was lucky and the owner just wanted it right... He didnt have to pay for the sweeper.....


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## bobelectric (Feb 24, 2007)

When I was a App., I was working in an office wiring 120 volt troffers.Done,turned on switch,BUZZZZZZ! On high Leg. Didn't know of such a thing.I was just the finish kid.


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## Speedy Petey (Jan 10, 2007)

mollydog said:


> ......., when he closed the 100 feeder breaker, lights were buzzing and it seems *he just turned off all the lights and went home*,.....


Wow! 





mollydog said:


> ..... the open space every other third phase should have caught his attention...


YA THINK??!!




While I have your attention, can you make your font a little bigger. It is way to small for my old eyes. :001_huh:


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## seo (Oct 28, 2008)

Seems like your friend would have checked voltage from phase to neutral before he turned on any power. He would have noticed his problem before any damage was done.


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## MDShunk (Jan 7, 2007)

I think many people have a high leg boo-boo in their career to talk about. Luckily mine was only a condensate pump and a light bulb. As they say, the Devil's in the details.


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## volty (Jan 14, 2009)

MDShunk said:


> I think many people have a high leg boo-boo in their career to talk about.


Yeah, easy way to find the computer circuits.


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## Magnettica (Jan 23, 2007)

Not all of us have screwed up equipment on a high-leg, open-delta service. I was lucky to work for an electrician early on who told me all about it and how to identify it by looking at the transformers on the outside of the building when in doubt. In theory I had a hard time understanding it for awhile, but eventually I got it. Now when I pull up to a job on the commercial/ industrial end, the service from the poco is the first thing I look for on the building.


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## leland (Dec 28, 2007)

MDShunk said:


> I think many people have a high leg boo-boo in their career to talk about. Luckily mine was only a condensate pump and a light bulb. As they say, the Devil's in the details.



Ya, mine was a panel change out. No damage, but I was quite new to flying solo.
Metered it and panicked.  Spent 3 hrs waiting for a more seasoned guy to call back and explain it to me.

let me tell ya,as a 'Green Horn' that gets your heart racing!!!

Never forgot it. check everything,before and after.


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## CNC (Dec 20, 2008)

I almost ruined my best shop vac! Don't just go switching breakers around to make room anymore! I'm very careful


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## Southeast Power (Jan 18, 2009)

Recently, I have been checking every panel I open during an estimate. 
If I find a hi-leg that is not marked orange, I write 120/240 inside of the panel or on the outside edge of the enclosure so you can see it with the cover removed.
Then I write high-leg on "B" unless its an older service and it is on "C"
I then draw a delta transformer, usually open and show where the center tap is.
I then draw a clock wise or counter clockwise arrow showing the ABC rotation.
Whole process takes about a minute and a half.
Not much room for an excuse after that.


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## Minuteman (Dec 29, 2007)

jrannis said:


> I then draw a clock wise or counter clockwise arrow showing the ABC rotation.


You carry your rotation meter with you while estimating?


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## 220/221 (Sep 25, 2007)

> I had a call from a good friend who is a top notch electrician,


 
Top notch eh? :jester::laughing::no::jester:

I am pretty sure I learned about the hi leg within the first month of my career, and I started in *residential.* If this guy was pulling new feeders he should have known better.


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## MDShunk (Jan 7, 2007)

jrannis said:


> Recently, I have been checking every panel I open during an estimate.
> If I find a hi-leg that is not marked orange, I write 120/240 inside of the panel or on the outside edge of the enclosure so you can see it with the cover removed.
> Then I write high-leg on "B" unless its an older service and it is on "C"
> I then draw a delta transformer, usually open and show where the center tap is.
> ...


I'd be ticked if you started scribbling all over my panels. I go to the trouble to wipe down panels when I'm done working in them, but I sure don't draw all over them. I'm not even sure that clockwise on one brand of phase rotation meter is clockwise on every brand of phase rotation meter.


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## Southeast Power (Jan 18, 2009)

MDShunk said:


> I'd be ticked if you started scribbling all over my panels. I go to the trouble to wipe down panels when I'm done working in them, but I sure don't draw all over them. I'm not even sure that clockwise on one brand of phase rotation meter is clockwise on every brand of phase rotation meter.


I only write inside of the panel.
The meter I use has been acccurate with the utility guys and every plant I've been in.


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## frenchelectrican (Mar 15, 2007)

The only thing I write in the breaker box if either wye or delta system is a triangle symbol and voltage that is anything else it will be written in proper place.

{ just watchout some old delta system they will have red marking instead of orange and verify it by voltmeter }

{ OT real quick In France the wild leg delta system is about nonexsting in the area }

Merci,Marc


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## patriot1 (Feb 16, 2009)

Shouldn't 120 volt circuits be illegal in a high leg panel???

"Things that make you go hmmmmm"


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## bobelectric (Feb 24, 2007)

MDShunk said:


> I'd be ticked if you started scribbling all over my panels. I go to the trouble to wipe down panels when I'm done working in them, but I sure don't draw all over them. I'm not even sure that clockwise on one brand of phase rotation meter is clockwise on every brand of phase rotation meter.


I wondered that ,myself. Any standards?


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## RePhase277 (Feb 5, 2008)

patriot1 said:


> Shouldn't 120 volt circuits be illegal in a high leg panel???
> 
> "Things that make you go hmmmmm"


Then it wouldn't be a high leg panel.


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## Bkessler (Feb 14, 2007)

InPhase277 said:


> Then it wouldn't be a high leg panel.



Some older guys I worked with in the past called it the "wild leg".


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## patriot1 (Feb 16, 2009)

I believe that the high leg panel should be for equipment use only, ie..a/c, motor, lighting, xfmrs...etc..strickly 3 phase or 1 phase items that would not "see" the "wild", "freak", "high" leg until it went to ground. There is a local church that has 120/208 and connected 3 single phase xfmrs so they could have a high leg to operate their a/c's more economically.


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## RePhase277 (Feb 5, 2008)

patriot1 said:


> I believe that the high leg panel should be for equipment use only, ie..a/c, motor, lighting, xfmrs...etc..strickly 3 phase or 1 phase items that would not "see" the "wild", "freak", "high" leg until it went to ground. There is a local church that has 120/208 and connected 3 single phase xfmrs so they could have a high leg to operate their a/c's more economically.


The high leg exists due to the requirement to power 120 V loads from a 240 V 3-phase delta. If you didn't need 120 V, you could drop the neutral, and therefore eliminate the high-leg. And, if you only served 3-phase loads, you wouldn't have a high leg to begin with.


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## zappy (Mar 6, 2009)

Bkessler said:


> Some older guys I worked with in the past called it the "wild leg".


Or the "stinger leg"


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## electricalperson (Jan 11, 2008)

whats the point of having 120/240v 3 phase when 120/208 3 phase is just as good and doesnt have a high leg? i dont think theres many 120/240v 3 phase services around here


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## RePhase277 (Feb 5, 2008)

electricalperson said:


> whats the point of having 120/240v 3 phase when 120/208 3 phase is just as good and doesnt have a high leg? i dont think theres many 120/240v 3 phase services around here


Places with large motor loads are best served by a delta service. The current through a delta transformer divides among the three windings, whereas with a wye each coil gets the full load. In other words, it is less strenuous on a delta service to supply a large load.


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## micromind (Aug 11, 2007)

If a building has an existing 120/240 single phase service, and 3 phase is needed for new equipment, it's much easier and less expensive to convert the existing service to a delta than a wye. The existing single phase panel can remain as-is, and a 3 phase panel can be added. The meter socket will need to be changed, and one more wire will need to be added to the service.

If it's overhead, it's simpler than you think, underground is a bit more involved. 

There are quite a few older buildings around here like this. If the service is changed to a 120/208 wye, the single phase panel will need to be replaced. The POCO around here will not connect a wye service with a single phase panel comprising the majority of the load. 

Rob


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## brian john (Mar 11, 2007)

duplicate...............


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## brian john (Mar 11, 2007)

patriot1 said:


> I believe that the high leg panel should be for equipment use only, ie..a/c, motor, lighting, xfmrs...etc..strickly 3 phase or 1 phase items that would not "see" the "wild", "freak", "high" leg until it went to ground. There is a local church that has 120/208 and connected 3 single phase xfmrs so they could have a high leg to operate their a/c's more economically.


 
If we make enough rules then we can employee stupider electricians, I'd like to think that we are smart enough to work around different power systems.

As for being more economical to operate HVAC equipment on there is no logic in that statement, that I can think of. PLEASE EXPLAIN!

There was a point in the history of distribution where 240/120 delta was very practical, with the advent of 480/277 VAC the 240/120 delta has been relegated to older industrial areas and existing utility distribution where upgrading is not cost effective.


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## Mark Lamont Ellison (Mar 15, 2010)

*just saying!!!!!!*




patriot1 said:


> I believe that the high leg panel should be for equipment use only, ie..a/c, motor, lighting, xfmrs...etc..strickly 3 phase or 1 phase items that would not "see" the "wild", "freak", "high" leg until it went to ground. There is a local church that has 120/208 and connected 3 single phase xfmrs so they could have a high leg to operate their a/c's more economically.


.....:no:....Probally wasn't for economic reasons, more like that some body sold them on the idea.:thumbup: remember '"watts are watts no matter what'' be it 3 phase or single phase! And besides the cost of all them xfmrs and work is never gonna be recovered. The meter will continue to turn the same speed mayby alittle faster if its an aful hot summer roasting all of the xfmr windings.


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## jwjrw (Jan 14, 2010)

Ive onle seen one in my career. An old mill building. My father has been doing this 40 years and said he has only ran across a few. It was used here mostly in industrial buildings that had alot of motor loads. I dont think there are many left here anymore.


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## Inspector Grump (Jun 4, 2008)

Only us old guy rember the delta services. Ever here of a delta with a grounded phase? That one can throw you a curve:whistling2:


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## amptech (Sep 21, 2007)

120/240 3Ø is very common around here. The reason is it was more economical when the 3Ø was necessary but was a small part of the over-all load. You can derive it with only 2 transformers instead of 3. That made it handy for rural co-ops to get 3Ø to farms for grain handling equipment that was only used seasonally.


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## Nephi (Mar 20, 2010)

its called a grounded corner and in my city they always ground A phase. it gives the delta system ground potential.


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## Magnettica (Jan 23, 2007)

Old buildings are the dead giveaway that you might be working on a HIGH LEG service.


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## B4T (Feb 10, 2009)

Magnettica said:


> Old buildings are the dead giveaway that you might be working on a HIGH LEG service.


 
I agree and I also look for (2) pots sitting on the pole as a clue what I'm in for


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## mattsilkwood (Sep 21, 2008)

Around here nearly all of the industrial plants have upgraded over the years, There is still a few commercial sites that have a wild leg. 

Most of the wild leg services I have seen are on older houses. 
The reasoning I have always gotten is the HVAC, not because it was cheaper to operate but because it was cheaper to buy a three phase unit.
How true that is I don't know.

My wild leg oops was a fart fan at a buddys house. That thing would suck the terd right out of the toilet, for just a minute.:laughing:

I have heard it called a bastard leg before.


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## danickstr (Mar 21, 2010)

what would happen if you put a 240 breaker across the two low legs, would the power just be a bit less? 

A guy I was working with once put in a temp power recept. for the workers and he put it on the high leg ( old building). A good old Milwaukee 1/2 jobber drill just sped up, and worked all day. The guy said it sounded "fast" but he didnt think about it.


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## mattsilkwood (Sep 21, 2008)

danickstr said:


> what would happen if you put a 240 breaker across the two low legs, would the power just be a bit less?
> 
> A guy I was working with once put in a temp power recept. for the workers and he put it on the high leg ( old building). A good old Milwaukee 1/2 jobber drill just sped up, and worked all day. The guy said it sounded "fast" but he didnt think about it.


 A-B, B-C and A-C will all be 240v but you will have one leg that is 240v to ground, that is your wild leg. The other two legs will be 120v to ground


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## danickstr (Mar 21, 2010)

thanks. i guess I don't get the theory behind why the a-c 240 is the same as the a-b 240, if the b leg is the high leg. I may have understood it at one time, but it is gone from the noodle.


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## brian john (Mar 11, 2007)

He made several mistakes. Not visually checking everything (which should be a clue) and TESTING EVERYTHING before and after work


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## danickstr (Mar 21, 2010)

i would think that many journeymen may never have seen a Delta 240 system. They are mainly in old buildings, and many municipalities have removed them. I admit that it was probably on a test at one time, and the gap of every third breaker(unless there is mainly 240 loads) are good reason to be critical, but I can see a problem.


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