# High Leg System



## Dennis Alwon (May 9, 2009)

The high leg has been known to be on the C phase. I don't believe their is a code issue on it but rather what the power company may require or what is normally used in that area.


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## don_resqcapt19 (Jul 18, 2010)

Dennis Alwon said:


> The high leg has been known to be on the C phase. I don't believe their is a code issue on it but rather what the power company may require or what is normally used in that area.


I don't understand. The code has required the high leg to be on B phase since before I started in the trade. The power company often landed the high leg on the C phase in the meter, but the electrician was required to land it on B phase in the service equipment.

As far as I know, even where the power company landed the high leg in the C phase position, it was actually B phase in terms of the phase rotation. Landing it in the C phase position had something to do with the metering equipment operation.


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## Dennis Alwon (May 9, 2009)

don_resqcapt19 said:


> I don't understand. The code has required the high leg to be on B phase since before I started in the trade. The power company often landed the high leg on the C phase in the meter, but the electrician was required to land it on B phase in the service equipment.
> 
> As far as I know, even where the power company landed the high leg in the C phase position, it was actually B phase in terms of the phase rotation. Landing it in the C phase position had something to do with the metering equipment operation.


You are correct-- I looked for it in 110 but it is in art. 408. B phase is high leg but I have heard others say their area required it on C phase.


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## Pete m. (Nov 19, 2011)

Our POCO requires it to be C phase and identified with purple...:blink:

After the meter or C/T can the electrician puts it on B and marks it with orange.

Pete


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## Dennis Alwon (May 9, 2009)

Had the old brain fart-- I always thought the B phase was required but when I read 110.15 it didn't mention B phase. I thought I was incorrect about the B phase. Found it later in 408.3(E)


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## don_resqcapt19 (Jul 18, 2010)

Pete m. said:


> Our POCO requires it to be C phase and identified with purple...:blink:
> 
> After the meter or C/T can the electrician puts it on B and marks it with orange.
> 
> Pete


There is no code reason why the color has to be changed from purple to orange.


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## Pete m. (Nov 19, 2011)

don_resqcapt19 said:


> There is no code reason why the color has to be changed from purple to orange.


True. Thats just how it's identified around here.

Pete


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## Jlarson (Jun 28, 2009)

A lot of older installs just carry the high leg from C position at the the meter and carry right through to the panel.

Often with HLD services it's preferred to have three phase main panels with single phase subs. Use the three phase panel for the three phase loads and any 2 wire 240v single phase loads to balance as best as possible. All the 3 wire 240 volt loads and the 120 stuff go in the single phase panel. Gives you the best usage of spaces and adds a bit (a tiny bit) of idiot resistance.


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## Chrisibew440 (Sep 13, 2013)

don_resqcapt19 said:


> There is no code reason why the color has to be changed from purple to orange.


Actually it does say orange.


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## Pete m. (Nov 19, 2011)

Chrisibew440 said:


> Actually it does say orange.


It does say orange but it also says "or by other effective means".

An AHJ may interpret that purple tape is an effective means.

Pete


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## seabee41 (Dec 21, 2010)

Here in Chicago B phase red tape. Stupid yes


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## Chrisibew440 (Sep 13, 2013)

Pete m. said:


> It does say orange but it also says "or by other effective means".
> 
> An AHJ may interpret that purple tape is an effective means.
> 
> Pete


True. I just keep it orange. That's the norm.


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## btharmy (Jan 17, 2009)

Pete m. said:


> It does say orange but it also says "or by other effective means".
> 
> An AHJ may interpret that purple tape is an effective means.
> 
> Pete


Most guys around here (including me) have always interpreted this another way, that it was to be identified with the color orange. The orange identification can be either by its outer covering (THHN with orange insulation) or another effective means like orange phase tape or orange paint. The constant being that it was orange.


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## Awg-Dawg (Jan 23, 2007)

btharmy said:


> Most guys around here (including me) have always interpreted this another way,


Do you agree that by"other means" that you can mark it with a tag or something similar?


Pete m. said:


> It does say orange but it also says "or by other effective means".
> 
> An AHJ may interpret that purple tape is an effective means.


 That is how I see it.


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## varmit (Apr 19, 2009)

I will asume that the original service is 240 volt three phase? If you are adding any 240 volt, single phase loads - THAT DO NOT HAVE ANY 120 VOLT EQUIPMENT CONNECTED WITHOUT AN UPSTREAM TRANSFORMER, you can connect one leg of a 240 volt, single phase load to the "high leg." Any equipment that is 240 volt only (with no neutral required) will function just fine using the "high leg", as the high leg to either of the other phases will read 240 volts.

BE CERTAIN TO NOT CONNECT ANY 120 VOLT LOADS TO THE HIGH LEG, AS THE HIGH LEG TO NEUTRAL WILL READ ABOUT 208 VOLTS.


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## Pete m. (Nov 19, 2011)

varmit said:


> I will asume that the original service is 240 volt three phase? If you are adding any 240 volt, single phase loads - THAT DO NOT HAVE ANY 120 VOLT EQUIPMENT CONNECTED WITHOUT AN UPSTREAM TRANSFORMER, you can connect one leg of a 240 volt, single phase load to the "high leg." Any equipment that is 240 volt only (with no neutral required) will function just fine using the "high leg", as the high leg to either of the other phases will read 240 volts.
> 
> BE CERTAIN TO NOT CONNECT ANY 120 VOLT LOADS TO THE HIGH LEG, AS THE HIGH LEG TO NEUTRAL WILL READ ABOUT 208 VOLTS.


I agree with you but you had best watch the type of breaker you use if it is connected to B phase. A slash rated breaker is a no go... i.g. 120/240.

Pete


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## farlsincharge (Dec 31, 2010)

A three phase panel with a neutral on a high leg system? Is that not forbidden?


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## Pete m. (Nov 19, 2011)

farlsincharge said:


> A three phase panel with a neutral on a high leg system? Is that not forbidden?


Nope.. used to be quite common. It's a fading system though. 

Pete


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## Awg-Dawg (Jan 23, 2007)

Pete m. said:


> Nope.. used to be quite common. It's a fading system though.
> 
> Pete


 
Last one I did was 5 years ago.

I don't remember one before that.


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## farlsincharge (Dec 31, 2010)

Pete m. said:


> Nope.. used to be quite common. It's a fading system though.
> 
> Pete


Still very prevalent here, but if the panel has a neutral you cannot bring the high leg in.
Three phase loads are fed out of switches or panels without neutrals.


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## Southeast Power (Jan 18, 2009)

MosT of the small commercial 3 phase here are open Delta.
We will always use it it for single phase 240 loads.
Our POCO lands it as C phase, we move to to B and mark it as orange.

We do normally install a separate single phase panel anticipating the arrival of the handyman.


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## varmit (Apr 19, 2009)

Pete m. said:


> I agree with you but you had best watch the type of breaker you use if it is connected to B phase. A slash rated breaker is a no go... i.g. 120/240.
> 
> Pete


Correct, a detail that I left out.


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## MHElectric (Oct 14, 2011)

Pete m. said:


> I agree with you but you had best watch the type of breaker you use if it is connected to B phase. A slash rated breaker is a no go... i.g. 120/240.
> 
> Pete


How hard would it be to hunt down a single pole breaker rated for 208/240v? Obviously, depending on what type of panel it is. 

If I wanted to add some lights off a wild leg, and use a multi-tap ballast, what ends of the earth would I have to travel to, to make this happen?


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## Awg-Dawg (Jan 23, 2007)

farlsincharge said:


> Still very prevalent here, but if the panel has a neutral you cannot bring the high leg in.
> Three phase loads are fed out of switches or panels without neutrals.


They don't trust you guys at all do they.

So they guys who make the rules understand the systems but you don't.

Im not making a joke, but that is what it seems like.


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## farlsincharge (Dec 31, 2010)

Awg-Dawg said:


> They don't trust you guys at all do they.
> 
> So they guys who make the rules understand the systems but you don't.
> 
> Im not making a joke, but that is what it seems like.


They make us set everything up so handymen can do the work. Or so it seems.


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## Southeast Power (Jan 18, 2009)

MHElectric said:


> How hard would it be to hunt down a single pole breaker rated for 208/240v? Obviously, depending on what type of panel it is.
> 
> If I wanted to add some lights off a wild leg, and use a multi-tap ballast, what ends of the earth would I have to travel to, to make this happen?


Don't do that..:no:


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## MHElectric (Oct 14, 2011)

jrannis said:


> Don't do that..:no:


Coming from personal experience?


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## Southeast Power (Jan 18, 2009)

MHElectric said:


> Coming from personal experience?


I saw it done once and couldn't believe how proud he was about it.


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## MHElectric (Oct 14, 2011)

jrannis said:


> I saw it done once and couldn't believe how proud he was about it.


......is there any bad news that went with this story?


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## farlsincharge (Dec 31, 2010)

MHElectric said:


> ......is there any bad news that went with this story?


There is a thread here where someone explains why it is bad. I don't remember the details


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## Pete m. (Nov 19, 2011)

MHElectric said:


> How hard would it be to hunt down a single pole breaker rated for 208/240v? Obviously, depending on what type of panel it is.
> 
> If I wanted to add some lights off a wild leg, and use a multi-tap ballast, what ends of the earth would I have to travel to, to make this happen?


I have never seen or heard of a breaker with such a rating. Although, I can't say that it isn't made.

I don't think the Earth is big enough for the install you are proposing:no:.

Pete


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## zen (Jun 15, 2009)

I personally don't prefer the high leg orange. With 277\480 being brown orange yellow, it seems like a good way to make a mistake if it gets assumed to be one or the other. Also here in tx poco has labels in meter base saying high leg must be landed on c phase of service entrance. Guys from poco said something about high leg being on the outside leg of a transformer and they use purple because orange is too often assumed to be 277v


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## Adam12 (May 28, 2008)

The POCO terminates the high leg on the "C" phase because the meter needs 120V and gets it from the "B" phase.


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## MHElectric (Oct 14, 2011)

I'd still love to hear a story of why tying some multi-tap lights onto a 208 high leg blew up the world.

Anybody got one?


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## wildleg (Apr 12, 2009)

it won't blow up the world. It's just supposedly the winding for the 208 is lighter than the others, apparently, and could easily be overloaded if the other (balanced) ckts approach the full loading.

I found another thread that touched on it:

http://www.electriciantalk.com/f9/120-240-volt-3-phase-delta-high-leg-5166/


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## Southeast Power (Jan 18, 2009)

Alex422 said:


> I have a question in regards to the Wild Leg being installed on the wrong phase. This panel has the wild leg on Phase C. Was it done this way in the 70's?
> 
> I am having to add another panel off of the main, and I have no use of the wild leg.
> 
> ...


The high leg is derived from a second transformer, if you Dont use it, it won't make any difference to your other loads.


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## Big John (May 23, 2010)

I actually really always wanted to put 208V lighting on a high leg. I woulda done it, too, if it wasn't for those meddling kids.

The only thing I can think of off-hand that someone might have to be careful of is if it's a group of banked 1Ø cans and the two high-leg transformers are only sized for the 3Ø load, then I could see a large high-leg load causing problems.


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## Pete m. (Nov 19, 2011)

Big John said:


> I actually really always wanted to put 208V lighting on a high leg. I woulda done it, too, if it wasn't for those meddling kids.
> 
> The only thing I can think of off-hand that someone might have to be careful of is if it's a group of banked 1Ø cans and the two high-leg transformers are only sized for the 3Ø load, then I could see a large high-leg load causing problems.


We all know that breakers that are slash rated.. i.g 120/240 cannot be used on the high leg but just for the sake of discussion what if someone were to install a 277/480 volt rated panelboard?

The breakers would no longer be a concern if you wanted to use the high leg to feed 208 volt lighting.

What would be the code violation?

Pete


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## Pete m. (Nov 19, 2011)

And, just to preface the question... I had someone do exactly that. It didn't feel right, look right and probably wasn't but short of 110.3(B) I had no real way of disapproving the install.

Pete


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## micromind (Aug 11, 2007)

Provided the breaker can handle the fault current at 208, there's nothing wrong with using the high leg and the neutral for 208 1ø loads. 

The reason the POCO requires the high leg to be on phase C at the meter is because C is the only one that can accurately measure watts with 208 to neutral The other two legs are calibrated at 120. 

Using the high leg to neutral of a closed ∆ system will load all 3 transformers roughly the same. Using it with an open ∆ will load each transformer equally, but the load on the ∆ transformer will be across the full winding, it'll be across 1/2 of the winding on the 120/240 transformer.


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## hardworkingstiff (Jan 22, 2007)

If anyone has or can find an image of the sine waves of a 120/240 Delta system, please be kind and post it.


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## Southeast Power (Jan 18, 2009)

varmit said:


> I will asume that the original service is 240 volt three phase? If you are adding any 240 volt, single phase loads - THAT DO NOT HAVE ANY 120 VOLT EQUIPMENT CONNECTED WITHOUT AN UPSTREAM TRANSFORMER, you can connect one leg of a 240 volt, single phase load to the "high leg." Any equipment that is 240 volt only (with no neutral required) will function just fine using the "high leg", as the high leg to either of the other phases will read 240 volts.
> 
> BE CERTAIN TO NOT CONNECT ANY 120 VOLT LOADS TO THE HIGH LEG, AS THE HIGH LEG TO NEUTRAL WILL READ ABOUT 208 VOLTS.


Uh, we don't do this. We always have some weird problem show up.


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## Southeast Power (Jan 18, 2009)

MHElectric said:


> ......is there any bad news that went with this story?


It was a tire balancing machine and it just didn't like the voltage it was like it was unstable or something. Then their is that whole slash rated breaker thing that didn't happen either.
He lost that account doing that among other hack stuff.
I know in theory it looks good but, it's not for me.


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## Southeast Power (Jan 18, 2009)

micromind said:


> Provided the breaker can handle the fault current at 208, there's nothing wrong with using the high leg and the neutral for 208 1ø loads.
> 
> The reason the POCO requires the high leg to be on phase C at the meter is because C is the only one that can accurately measure watts with 208 to neutral The other two legs are calibrated at 120.
> 
> Using the high leg to neutral of a closed ∆ system will load all 3 transformers roughly the same. Using it with an open ∆ will load each transformer equally, but the load on the ∆ transformer will be across the full winding, it'll be across 1/2 of the winding on the 120/240 transformer.


Nothing wrong with it but, have you done this very often?


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## micromind (Aug 11, 2007)

jrannis said:


> Nothing wrong with it but, have you done this very often?


Not with a breaker in a panel, mainly because of the voltage/AIC. 

A while ago, I connected an older CNC machine to a 120/240 3ø ∆ system. It had no control power transformer, so I pulled a neutral. It also had an immersion heater in the hydraulic oil tank that was 208 1ø. The motors were basic 230/460, connected for 230. All circuits were protected by fuses. 

So I connected the heater (3kw, if I remember) from the high leg to neutral. 

I've been back to that shop occasionally over the years; never heard of a problem with that machine.


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## micromind (Aug 11, 2007)

jrannis said:


> Uh, we don't do this. We always have some weird problem show up.


That's odd, I've connected tons of 240 1ø stuff (no neutral) using the high leg and one of the 120 legs and have yet to have an issue. Even electronic stuff. 

Maybe a local POCO issue or something.

And yes, I always use a straight 240 breaker, even though they are more expensive that a 120/240 one is.


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## Southeast Power (Jan 18, 2009)

micromind said:


> That's odd, I've connected tons of 240 1ø stuff (no neutral) using the high leg and one of the 120 legs and have yet to have an issue. Even electronic stuff.
> 
> Maybe a local POCO issue or something.
> 
> And yes, I always use a straight 240 breaker, even though they are more expensive that a 120/240 one is.


Yes one of the phases to the high leg is good. High leg to neutral was never kosher here.


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## JRaef (Mar 23, 2009)

micromind said:


> Not with a breaker in a panel, mainly because of the voltage/AIC.
> 
> A while ago, I connected an older CNC machine to a 120/240 3ø ∆ system. It had no control power transformer, so I pulled a neutral. It also had an immersion heater in the hydraulic oil tank that was 208 1ø. The motors were basic 230/460, connected for 230. All circuits were protected by fuses.
> 
> ...


You had a heater rated to put out 3kW at 208V. That means the heater element resistance was 208^2/3000 = 14.42 ohms.

You connected it from the High line to Neutral, so the voltage would be 138.6V (240 / 1.732). 

Your heater became a 1333W heater (138.6V^2 / 14.4ohms), less than half of what it was rated for. It would work, it would just take a lot longer to heat up the oil. That only works because it was a resistance load.


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## hardworkingstiff (Jan 22, 2007)

JRaef said:


> You connected it from the High line to Neutral, so the voltage would be 138.6V (240 / 1.732).


Every Delta with a center tap neutral on one winding that I've put a meter on was 208V from H-leg to neutral. You are way smarter than me, but field experience says that formula is missing something.

If it was a 240V phase to phase Wye, then line to neutral would be 138.6V, right?


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## Vintage Sounds (Oct 23, 2009)

JRaef said:


> You had a heater rated to put out 3kW at 208V. That means the heater element resistance was 208^2/3000 = 14.42 ohms.
> 
> You connected it from the High line to Neutral, so the voltage would be 138.6V (240 / 1.732).
> 
> Your heater became a 1333W heater (138.6V^2 / 14.4ohms), less than half of what it was rated for. It would work, it would just take a lot longer to heat up the oil. That only works because it was a resistance load.


How can the high leg not be 208 to neutral?

(240v + 120v) / 1.732 = 208v


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## Big John (May 23, 2010)

hardworkingstiff said:


> ...If it was a 240V phase to phase wye, then line to neutral would be 138.6V, right?


 Right.


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## JRaef (Mar 23, 2009)

Vintage Sounds said:


> How can the high leg not be 208 to neutral?
> 
> (240v + 120v) / 1.732 = 208v


Brain fart... I was trying to do two things as once. Screwed up the other one too...


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