Orange is always used to mark the "high" or "wild" leg, 208V to neutral. I wouldn't refer to this system as 120/208 because it is not a Y service. It's a 120/240 3-phase 4-wire system. Adding the neutral connection creates the "high" leg. The 3-phase aspect of this system is a 240V delta connection. It gives you 240V 3-phase for motor loads, etc. It gives you 120V 1-phase for lighting/outlets. Also available is 240V 1-phase for appliances. Your panel will have some wasted space due to the "high" leg.
120/240v colors are Black/Red/Blue; 2$0/480v or 277/480v colors are Brown/Orange/Yellow. At least in the US orange is not the normal/exclusive color for the high leg in high leg delta. Perhaps the orange was a really faded red as that would make more sense or perhaps the person was out of red tape.
NEC 2014 110.15 High leg Marking. The conductor having the higher phase voltage shall be durably and permanently marked by an outer finish that is orange in color.
He did mention at the beginning that someone had not marked the "B" phase Red so he added the orange tape to signify the high leg just in case anybody missed that..
I hope he helps you in hvac, but electrical apprentices need to close their eyes and earts when this guy talks. Even for you hvac guys he messed something up pretty big. It doesn't matter which 2 legs you switch if you accidentally wired it backwards. All 3 phase to phase volt readings will be 240, although he didn't even check a to c. Any switch between any 2 phases will reverse the polarity of all 3 phase ac motors
Hi David stumbled across your video while hunting for a better understanding on how to balance the legs on my 20 hp phase converter. After I have a bite to eat going to move the high leg from c (currently showing 200 volts) to B and hope it balances up from there. Thanks!!!
ya man I am about a year into maintenance_electrical and they didn't teach this in school. thanks for you're video it helps a lot. keep up the good work.
I have a couple of questions. First there's a Jones heating and plumbing in Plymouth, Indiana, about a half hour drive north of where I live. Are you part owned by the same company? Also in a 120/240/208 hi leg system what is the 208v wire (phase B to neutral) used for? I don't know of any household appliances that use that voltage.
NEC 110.15 . . . . . the conductor or busbar having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color or by other effective means. . . . .
Hi I am in Canada we got machine required 230v AC 3PH we bought transformer step down 600v to 230v with high leg so machine has two drives one 3 ph 230v AC and one single phase 230v AC . Electrician pull three wire and ground wire from transform to machine so after few month single phase drive fail when I check it was hookup with phase A&B I mean hot leg and one another leg but when I check those two with ground it shows 110v and 203 volt and when I check cross it shows 230v my question is 1. what was the correct way to step down the voltage and connect the machine 2. why when we measure voltage cross AB,BC,or CA it shows same voltage if B is hot leg then AB and BC should read alot higher then CA almost 40% higher 3. What you think drive fail because hot leg was connected. 4. why most of transform has not high leg 5. Transformer marked X1 X2 X3 and X6 (feed out) so X6 will treat as a neutral or as a ground in side the transformer they have jumper anyway thank you
I have a question, all brands of 3 phase package unit, always the high leg has to be connected in terminal b,,, I am a little confused in my disconnect I have a)120v-b)220v-c)120v,
the first thing we do with reverse voltage is switch A and C. Why? because they are both low legs, and for a common human there is no way to tell which is a and which is c, except with a phase instrument.
Great Video thanks. So just to confirm anybody can call you for tech support and advise if we are in need of support? If that's correct thank you for all you do.
I was familiar with wye systems but open-delta highleg was confusing me until I realized that phase to phase voltages are all the same. Sometimes it just takes a video like this to make it click in my head.
Just to clarify what you really have there. It is not a 208V 3PH service. It is a closed Delta 120/240V High leg(wild leg, stinger leg or wild phase) service. Between each phase you will have a nominal 240V (A-B, B-C, A-C) and between each phase to the grounded neutral conductor you will have 120V, 208V and 120V. The leg with 208V to neutral is the stinger or high leg. The typical phase to which the stinger leg should be connected is the B phase. On the panel in your video it is correctly connected and correctly marked with orange tape which is required by code to identify the high leg. No single phase circuits should be connected on the B phase bus terminals which is why you see several of the B slots with no breaker in them.
+Alex Millison In his defense the closed Delta 120/240V High leg service is not very common. It is usually found in cross over areas where residential services are mixed with mostly commercial services.
Most of these type installations are known as 240V "open-delta" three phase service. Open delta because the power company only uses two transformers where a closed delta requires three transformers. These were very popular in mostly rural areas(start of REA electric co-ops) where a power company can give a remote farmer three phase service to his grain equipment by running only two high voltage phases to his farm, saving a ton of money. Here is a typical transformer wiring diagram showing an open delta connection with the high leg. www.oempanels.com/240v-single-phase-and-240v-3-phase. Even though approved, good electricians will avoid taking single phase 120V/240 V load off a three phase, high leg main panel but instead mount a single phase lighting sub panel next to it, run the two 120 volt legs minus the high leg so 120 volt load won't be mistakenly connected to 208V by the next electrician salivating over all of the empty slots on the 3 phase panel. Many electricians fail to test for the high leg and have burned up lot's of equipment. As full three phase power company systems are being installed in built up areas, power companies are shifting toward the elimination of the high leg for the safety value. Power companies spec these high leg systems where most of the connected load is 3 phase with incidental single phase load. After all connecting too much single phase load on phase A and phase B results in phase unbalance for the system transformers. Be careful out there!
i have two welders with ac power with 50 amps 3 p, can they be hooked up together to double the cut on a plaza torch, 1 Lincoln guy stated get welder at same rmp and hook up wires respectable?
There are a lot of uses for the high leg of a 4 wire Delta system. Most of your latest L.E.D. light fixtures have universal voltage drivers (120 through 277V.) that will operate at 208v. and any voltage in between.
Alex Millison You can use a 3 pole breaker.. All of which are straight rated (240 volt). Either connect 1 phase to phase 240 volt load and a 208 volt load (high leg to neutral), or 2- 120 volt loads and a 208 volt load ( high leg to neutral).
Yes you're right, I was referring to if somebody was trying to use a single pole breaker in which case they don't make them with a 240V straight rating. And if somebody is going to use a 2 pole breaker to be able to use a high leg and nuetral, just use both spots and run 240v.
Except that most single-pole CB's are not rated over 125v. And, the NEC explicitly prohibits high-leg to neutral loads. But otherwise... totally okay. 😂😂
I have this type of power distribution to my house which was built to commercial standards back in 1940. I am curious as to the history of this type of distribution which I had not been aware of heretofore. I have learned that this type of distribution is properly called 3 phase 4 wire delta high leg? It seems like an ingenious method to provide both 3 phase and single phase power to a site which is ready to go without any additional on site transformers and using only 4 wires to get it there.
I have a 240/480 3 phase system with the high leg. From line to ground, I have: L1-242 VAC, L2-420 VAC, L3-242 VAC. Line to line averages at 482 VAC. I have a servo drive being powered by this system, but, my servo drive needs each leg to be balanced. Other than having to install a transformer to balance the system, what other options do I have?
Good question. Glad you asked. Unfortunately you don't have options other than to install step down transformers on each leg to balance the system, that's the major disadvantage of a high leg system. Assuming there is 240 volt equipment running off L1 to ground and L3 to ground, you could install three 480 to 240 volt or 120/240 volt transformers, to try and balance the system. In fact a 240/480 4 wire delta is pointless, I've heard of them but never worked with one. I've worked on 120/240 delta systems a handful of times. Normally with a 480 volt system it's 277/480 wye, your heavy equipment runs on 480, your lighting is 277, and there is a 480 to 120 transformer to power your general purpose 120 volt receptacles. This is how a shopping mall, or Walmart Supercenter, for example would be set up.
Great video, I have 3 phase high leg in an old building and am having trouble finding information on what types of 3 phase motors will work there for woodworking.
I agree with Barry Witt and his comments on his closed Delta theory about this article. One way to check is if you have 3 transformers on the utility pole supplying the service. They should be marked with the voltage and other information. To be sure call the utility. They have the information. Note: one of the transformers will be large and two of them will be smaller. The larger transformer (most likely) is supplying the 120 volt loads. NEC 110.15 High Leg marking on a 4 wire delta-connected system where the midpoint of one phase windings (Coil) is grounded, only the conductor or busbar shall be marked by an outer finish that is "ORANGE" or by other effective means. The high leg is common on a 240v/120v 3 phase, 4 wire delta system designated as B phase. "IMPORTANT" : The Utility which has a different code and guidelines. The "High leg" (Stinger, Wild leg, red leg) is on The "C PHASE" at the meter. In past NEC codes the C phase was the "high leg". The NEC changed the code to be on the B phase. Since the Utility uses a different code they kept the High Leg on the C phase. "IMPORTANT" always check any panel your working on like the gentleman did in this video. You don't know for certain how each supply was made up in the panel. Someone could have made a mistake. Another problem can be the wrong phase rotation. Hopefully if you have phases A,B,C with the Utility A,B,C your phase rotating will be correct. Unfortunately, If two of the phases are changed out of the phases A,B,C order the motor or motors will run backwards. You'll have to correct problem wiring by changing any two of the motors T connections. The phase rotation should be checked before the install. If the system is already installed you just have to work around problems such as the motors. Thank You for the video
Nice video. As an cautionary history note in many older installations the panel has the high leg on the far right C phase and often it is marked with red tape. Folks called it a "red leg delta"; or call the high 208 volt leg the "red leg". In modern panels the high leg is in the middle busbar B phase like this video and the the wire is taped most of the times Orange. Some older panels have the middle B phase high leg tapped Blue or Purple too. Thus like the video use your meter to find out which lug is really the high leg. Disco era i.e. mid/late 1970's and before are older panels. They are also the majority of 3 phase 4 wire 240 volt delta panels in many places. Thus modern code has A and C 120 volt and B as 208 to neutral. Older installs are often A and B 120 volts and C is 208 volts to neutral. All have 240 volts between each phase. The current NEC requires the high leg to be the B phase bus in switchboards and panel boards. BUT it once was required to the C Phase bus at the far right of the panel.
I like the video. I guess there's no way to tell if the A and C legs are reversed?? Since they are both approx 120 or is the 243 volts and 235 volts between A and B and B and C the way you would tell?? Thanks...
I have 3 phase panel a,b is 120 and C leg is 220 i like to replace only bas bar .if i get same brand panel instead changing hall panel can i only change bas bar thanks
Your high keg should be on B phase, but I would not recommend swapping it. If you change out your panel make sure no single pole breakers get installed on your high leg
The panel box is labeled correctly. By removing that orange tape on the B phase, you are held liable. If you were to open the transformer, you would see on the secondary side PHASE A=BLACK PHASE B=ORANGE, not red PHASE C=BLUE
So have an existing panel that is reading 123 on both A and B phase but for some reason C phase is showing 216. The panel is supposed to be set up for commercial A/C’s with two 70 amp 3 phase breakers. Any ideas??
In that case based on your readings you have a 120/240V 3ø 4w system, and the high leg is terminated on the C phase. In installations before 1975, this was typically the case, but after 1975 the high leg should have been terminated on phase B. High leg should be orange, and regardless of the panels you should always verify with a meter before connecting stuff. Do not rely on colors or labels.
This is a 3 phase delta (high leg)system. Voltages are 120/208/240. You most likely are dealing with a 120/208 wye system. Phase to phase should give you 208 and each phase to neutral will give you 120. It has to do with the configuration of the transformer. Hopefully this helps
If you had measured all three phases against each other and if you got 208volts and 120volts from neutral to each line then it would've been a 120/208Y system
I can't see how u get 208v from hot to neutral I service In ny and it's usually 123 to ground on each phase 208/240 between each phase 123 or abc so again huh
Your three phase service is a WYE type of service, and his is not. His is also known as a high-leg or wild-leg delta system. That's why there is a 208V from high leg to neutral.
208 volts to ground is not an intended voltage in this application, it just happens to be a byproduct of the transformer configuration. The typical application for this type of service would be in commercial or industrial settings where the majority of the loads are 3 phase motors, with a small amount of 120V loads. Typically these systems are found in older buildings in rual areas, you rarely see them being installed as new systems.
Why do we have different voltages and phases all over the world, maybe there should be a standard? Thanks for your comment, I like Hearing from my friends across the pond.
There are lots of standards, primarily managed by the IEEE. As for one common global one? Blame George Westinghouse, Thomas Edison, and Nikola Tesla for inventing electricity in America before the internet would have allowed them to readily share (and license) their specific approaches to lighting, motors, transformers, generation, transmission, and distribution. Mohammed Ali hadn't been born yet to create the Butterfly Effect.
Phase B to ground is 208 because it's a 120/240 3 phase delta. You'll have 240v between any two phases. Phase a and c will be 120v and phase b will be 208v. Simply put, phase b has to travel the furthest distance to the nuetral in this delta system. If you take the square root of 3 (1.732) and times it by your line to nuetral voltage(120v) of phase a or c, that's how you get 208v.
Hi Mr Jones, I dont have good knowledge in electricity, just curious asking, does it dangerous using the multimeter to measure the voltage like what you did ?
ELFYHO if you don't know what you're doing. if you're not an electrician or have a working knowledge of electricity don't do it. you don't get second chances with electricity
Omg 3 phase wiring is so much simpler in NZ than the USA. We have L1, L2, L3 + N and + E Red , White , Blue, Black , Green/Yellow sometimes with out the Earth or sometimes with the Earth and not the Natural
Same as South Africa If we did a high leg like theirs, we would still have 400v phase to phase, but we would get 230v phase to neutral on the "high leg" and 200v phase to neutral on the other two. We don't bother, we just go 230v/400v.
@@jjoejones1 Thank you and I just did. You are correct for NEW installations, but there's an exception for additions to EXISTING installations so my original comment can hold true. B phase high leg would in most cases be required per code and conforms to industry standard, so it is best practice.
@@nickesposito3497 as an electrician myself, we have the golden rule: don't trust colors, trust your meter. And always wear your PPE when probing inside a live panel.
Very informative video. The only thing I can see the high leg being good for is lighting where you have a ballast that can run on 120-277V. 208V has always been a mystery to me.
+Daniel Peters The voltage between all three phases is 240V. It is only to ground that the high leg is 208V. Three phase devices rated for 240V can be connected A,B,C while split phase 240V devices can be connected across the two 120V legs and single phase 120V devices can be connected between either 120V leg to neutral. You just cannot connect a 120V single phase between the high leg and neutral.
Good explanation Dave If you can take some constructive criticism, I'll bet 5 dollars against a stale donunt there is probably 6000 amperes at that buss all ready to burn hide and meat through an arc-flash along with plasma particles to be injested when something goes wrong and the planets all line up. As an inspector if I observed someone doing this at a mine I would be obligated to issue and imminent danger order along with a citation that could cost in the 5 digit category. Other than that I'm a fan for sure. Bob
Agree. No PPE, but 208V high leg isnt likely to arc flash like 480V will. 6kA fault current is probably low. He also didnt check A-C phase, tho it's likely 240V given his other readings.
Never see delta here on the conditions that I seem to work in. Everything supplied here is Wye. In order to understand this condition you gave us some voltages but not all the voltages. you gave us A - N 121v B - N 208v C - N 122v N - Gnd 0v and A - B 243v B - C 235v but no A - C So the give away here for the delta connection is the high leg AND the 240ish voltage? So what is the low leg to low leg A - C voltage? 243ish 235ish or 208v? Also is my assumption that there are no 120v loads on the B phase to N at all in that panel? Nice upstaging job by your assistant. :)
Interesting stuff David! Our power here is 240V to neutral single phase or 415V between each of the three phases, there is no high leg. In some rural areas there a few split phase 480V two phase supplies but hey are still 240V to neutral just that the phases are 180' out instead of 120' as in three phase.
If you ever have 240 to N, something is wrong. You can have 277 to N, 120 to N, or 220 to N (in European countries). You shouldn't find 240 to N anywhere. Although, you can definitely get 240 by measuring across two 120 phases in a single phase 3 wire system.
Just because you wire you more ABC, does not guarantee you'll get the rotation you want. You have no idea what rotation the utility provider is giving you. They switch A and C phase because the utility power is the opposite rotation they need
birdchaser2010 most motors will say on the nameplate if they can operate on 208V. if it's a 240V appliance that has a fixed resistance like a heater, it's perfectly fine to run 208v to it. it'll just draw a little less current and not produce as much heat.
No PPE, fail. Meter leads not both in one hand, sometimes required but never recommended. Do try to avoid setting up a situation where the current path is thru your heart if something should go wrong.
@@jjoejones1 I think what willie isacz might have been referring to when banned, is what they called a delta breaker, that was used in a single phase panel to power one three phase load, typically in that era a 5 ton air conditioning unit. Most people probably have never seen a delta breaker or know that it existed, because it is a very oddball type. But yes 120/240 3ø4w is still allowed and sometimes still used in new installs, but is not nearly as common now as is was, say in the 50s and 60s. A common giveaway is 3 transformers on the pole, one of which is significantly larger than the other two. Another strong clue is in the panels with single pole breakers, every 3rd breaker opening is not used. These installs in this day and age really are kind of pointless, but you will run into them on different occasions.
@@Sparky-ww5re Thank you for your reply. I am familiar with Delta breakers but when Willie used the word ‘system’ in his comment, it did not appear he was referring to delta breakers. Regarding the transformer configuration for a 3-phase, 4-wire Delta. In my area it is more commonly seen as an ‘open’ delta which only requires (2) transformers as opposed to the ‘closed’ delta which requires (3) transformers.
The title should be "guy wearing golf shorts and wire rim glasses who doesn't know 3 phase from split single phase takes dumb risks in live panel with bare hands and hunts around with a meter trying to get an instant suntan" . This video should be taken down.
Its a 3 phase 240v delta. B phase high leg is by code labeled orange. Colors are
A Phase - Black
B Phase - Orange (high leg)
C Phase - Blue
Orange is always used to mark the "high" or "wild" leg, 208V to neutral. I wouldn't refer to this system as 120/208 because it is not a Y service. It's a 120/240 3-phase 4-wire system. Adding the neutral connection creates the "high" leg. The 3-phase aspect of this system is a 240V delta connection. It gives you 240V 3-phase for motor loads, etc. It gives you 120V 1-phase for lighting/outlets. Also available is 240V 1-phase for appliances. Your panel will have some wasted space due to the "high" leg.
120/240v colors are Black/Red/Blue; 2$0/480v or 277/480v colors are Brown/Orange/Yellow. At least in the US orange is not the normal/exclusive color for the high leg in high leg delta. Perhaps the orange was a really faded red as that would make more sense or perhaps the person was out of red tape.
NEC 2014 110.15 High leg Marking. The conductor having the higher phase voltage shall be durably and permanently marked by an outer finish that is orange in color.
He did mention at the beginning that someone had not marked the "B" phase Red so he added the orange tape to signify the high leg just in case anybody missed that..
@@ericstandefer9138 110.15 Or by other effective means, so in reality it could be any color.
No… the high leg has to be orange. You can’t pick any random color
I just can not thank you enough for those great videos, they been a great help to understand better my new trade on hvac, God bless you.
I hope he helps you in hvac, but electrical apprentices need to close their eyes and earts when this guy talks. Even for you hvac guys he messed something up pretty big. It doesn't matter which 2 legs you switch if you accidentally wired it backwards. All 3 phase to phase volt readings will be 240, although he didn't even check a to c. Any switch between any 2 phases will reverse the polarity of all 3 phase ac motors
Thank you for a great explanation and showing exactly how to test for this! Great job!
Thank you for that comment. I am so glad it helps.
I enjoyed the video. I found it very educational, thank you very much.
It does really help a lot. Thank you david!
Really good thanks for sharing your knowledge
Hi David stumbled across your video while hunting for a better understanding on how to balance the legs on my 20 hp phase converter. After I have a bite to eat going to move the high leg from c (currently showing 200 volts) to B and hope it balances up from there. Thanks!!!
This is a high leg delta 3 phase. Not a 208/120 three phase. Delta never came out of your mouth.
Thanks
For your good videos keep up the safe and good work
Thanks for the comment.
ya man I am about a year into maintenance_electrical and they didn't teach this in school. thanks for you're video it helps a lot. keep up the good work.
As an electrician, please don't listen to this man. This is common for an hvac guy to play electrician. High leg is always orange.
nice simple and explained very well
I have a couple of questions. First there's a Jones heating and plumbing in Plymouth, Indiana, about a half hour drive north of where I live. Are you part owned by the same company? Also in a 120/240/208 hi leg system what is the 208v wire (phase B to neutral) used for? I don't know of any household appliances that use that voltage.
Thanks, have a great day.
NEC 110.15 . . . . . the conductor or busbar having the higher phase voltage to ground shall
be durably and permanently marked by an outer finish that is orange in color or by other
effective means. . . . .
Great explanation. Thanks.
Good video thanks for the info.
Do you do the same thing for 480vac?
Hi I am in Canada we got machine required 230v AC 3PH we bought transformer step down 600v to 230v with high leg so machine has two drives one 3 ph 230v AC and one single phase 230v AC . Electrician pull three wire and ground wire from transform to machine so after few month single phase drive fail when I check it was hookup with phase A&B I mean hot leg and one another leg but when I check those two with ground it shows 110v and 203 volt and when I check cross it shows 230v my question is 1. what was the correct way to step down the voltage and connect the machine 2. why when we measure voltage cross AB,BC,or CA it shows same voltage if B is hot leg then AB and BC should read alot higher then CA almost 40% higher 3. What you think drive fail because hot leg was connected. 4. why most of transform has not high leg 5. Transformer marked X1 X2 X3 and X6 (feed out) so X6 will treat as a neutral or as a ground in side the transformer they have jumper anyway thank you
I have a question, all brands of 3 phase package unit, always the high leg has to be connected in terminal b,,, I am a little confused in my disconnect I have a)120v-b)220v-c)120v,
Avery good informative post.
the first thing we do with reverse voltage is switch A and C. Why? because they are both low legs, and for a common human there is no way to tell which is a and which is c, except with a phase instrument.
Great Video thanks.
So just to confirm anybody can call you for tech support and advise if we are in need of support? If that's correct thank you for all you do.
need help wiring my sub pannale from the main box to the shed
thank you senor very helpful
Who put the panel at knee height?
I like your safety glasse and gloves
Im curious....is this delta configuration? because i thought it was impossible to get 240V with 3phase with a wye configuration....
I was familiar with wye systems but open-delta highleg was confusing me until I realized that phase to phase voltages are all the same. Sometimes it just takes a video like this to make it click in my head.
So this is a 4 wire delta correct? High leg is orange. Still learning , thanks for the video
Just to clarify what you really have there. It is not a 208V 3PH service. It is a closed Delta 120/240V High leg(wild leg, stinger leg or wild phase) service. Between each phase you will have a nominal 240V (A-B, B-C, A-C) and between each phase to the grounded neutral conductor you will have 120V, 208V and 120V. The leg with 208V to neutral is the stinger or high leg. The typical phase to which the stinger leg should be connected is the B phase. On the panel in your video it is correctly connected and correctly marked with orange tape which is required by code to identify the high leg. No single phase circuits should be connected on the B phase bus terminals which is why you see several of the B slots with no breaker in them.
+Alex Millison In his defense the closed Delta 120/240V High leg service is not very common. It is usually found in cross over areas where residential services are mixed with mostly commercial services.
Barry Witt My brother you are absolutely correct.
Most of these type installations are known as 240V "open-delta" three phase service. Open delta because the power company only uses two transformers where a closed delta requires three transformers. These were very popular in mostly rural areas(start of REA electric co-ops) where a power company can give a remote farmer three phase service to his grain equipment by running only two high voltage phases to his farm, saving a ton of money. Here is a typical transformer wiring diagram showing an open delta connection with the high leg.
www.oempanels.com/240v-single-phase-and-240v-3-phase.
Even though approved, good electricians will avoid taking single phase 120V/240 V load off a three phase, high leg main panel but instead mount a single phase lighting sub panel next to it, run the two 120 volt legs minus the high leg so 120 volt load won't be mistakenly connected to 208V by the next electrician salivating over all of the empty slots on the 3 phase panel.
Many electricians fail to test for the high leg and have burned up lot's of equipment. As full three phase power company systems are being installed in built up areas, power companies are shifting toward the elimination of the high leg for the safety value. Power companies spec these high leg systems where most of the connected load is 3 phase with incidental single phase load. After all connecting too much single phase load on phase A and phase B results in phase unbalance for the system transformers. Be careful out there!
Barry Witt what happens if you tie in a single phase 120 to a b phase 208
i have two welders with ac power with 50 amps 3 p, can they be hooked up together to double the cut on a plaza torch, 1 Lincoln guy stated get welder at same rmp and hook up wires respectable?
Awesome!
helpful video thank you
There are a lot of uses for the high leg of a 4 wire Delta system. Most of your latest L.E.D. light fixtures have universal voltage drivers (120 through 277V.) that will operate at 208v. and any voltage in between.
But most breakers you'll find are not rated for more than 120v.
Alex Millison You can use a 3 pole breaker.. All of which are straight rated (240 volt). Either connect 1 phase to phase 240 volt load and a 208 volt load (high leg to neutral), or 2- 120 volt loads and a 208 volt load ( high leg to neutral).
Yes you're right, I was referring to if somebody was trying to use a single pole breaker in which case they don't make them with a 240V straight rating. And if somebody is going to use a 2 pole breaker to be able to use a high leg and nuetral, just use both spots and run 240v.
Except that most single-pole CB's are not rated over 125v. And, the NEC explicitly prohibits high-leg to neutral loads.
But otherwise... totally okay. 😂😂
I have this type of power distribution to my house which was built to commercial standards back in 1940. I am curious as to the history of this type of distribution which I had not been aware of heretofore. I have learned that this type of distribution is properly called 3 phase 4 wire delta high leg? It seems like an ingenious method to provide both 3 phase and single phase power to a site which is ready to go without any additional on site transformers and using only 4 wires to get it there.
I have a 240/480 3 phase system with the high leg. From line to ground, I have: L1-242 VAC, L2-420 VAC, L3-242 VAC. Line to line averages at 482 VAC. I have a servo drive being powered by this system, but, my servo drive needs each leg to be balanced. Other than having to install a transformer to balance the system, what other options do I have?
Good question. Glad you asked. Unfortunately you don't have options other than to install step down transformers on each leg to balance the system, that's the major disadvantage of a high leg system. Assuming there is 240 volt equipment running off L1 to ground and L3 to ground, you could install three 480 to 240 volt or 120/240 volt transformers, to try and balance the system. In fact a 240/480 4 wire delta is pointless, I've heard of them but never worked with one. I've worked on 120/240 delta systems a handful of times. Normally with a 480 volt system it's 277/480 wye, your heavy equipment runs on 480, your lighting is 277, and there is a 480 to 120 transformer to power your general purpose 120 volt receptacles. This is how a shopping mall, or Walmart Supercenter, for example would be set up.
Glad it helped.
Great video, I have 3 phase high leg in an old building and am having trouble finding information on what types of 3 phase motors will work there for woodworking.
+Jordan Ward 208/240V dual voltage three phase motors will work just fine.
Those used with rotary converter on split phase.
Thank you sir
I agree with Barry Witt and his comments on his closed Delta theory about this article. One way to check is if you have 3 transformers on the utility pole supplying the service. They should be marked with the voltage and other information. To be sure call the utility. They have the information. Note: one of the transformers will be large and two of them will be smaller. The larger transformer (most likely) is supplying the 120 volt loads. NEC 110.15 High Leg marking on a 4 wire delta-connected system where the midpoint of one phase windings (Coil) is grounded, only the conductor or busbar shall be marked by an outer finish that is "ORANGE" or by other effective means. The high leg is common on a 240v/120v 3 phase, 4 wire delta system designated as B phase. "IMPORTANT" : The Utility which has a different code and guidelines. The "High leg" (Stinger, Wild leg, red leg) is on The "C PHASE" at the meter. In past NEC codes the C phase was the "high leg". The NEC changed the code to be on the B phase. Since the Utility uses a different code they kept the High Leg on the C phase. "IMPORTANT" always check any panel your working on like the gentleman did in this video. You don't know for certain how each supply was made up in the panel. Someone could have made a mistake. Another problem can be the wrong phase rotation. Hopefully if you have phases A,B,C with the Utility A,B,C your phase rotating will be correct. Unfortunately, If two of the phases are changed out of the phases A,B,C order the motor or motors will run backwards. You'll have to correct problem wiring by changing any two of the motors T connections. The phase rotation should be checked before the install. If the system is already installed you just have to work around problems such as the motors. Thank You for the video
In my area, alot of 3 phase delta services are open deltas using only 2 transformers.
Nice video. As an cautionary history note in many older installations the panel has the high leg on the far right C phase and often it is marked with red tape. Folks called it a "red leg delta"; or call the high 208 volt leg the "red leg". In modern panels the high leg is in the middle busbar B phase like this video and the the wire is taped most of the times Orange. Some older panels have the middle B phase high leg tapped Blue or Purple too. Thus like the video use your meter to find out which lug is really the high leg. Disco era i.e. mid/late 1970's and before are older panels. They are also the majority of 3 phase 4 wire 240 volt delta panels in many places. Thus modern code has A and C 120 volt and B as 208 to neutral. Older installs are often A and B 120 volts and C is 208 volts to neutral. All have 240 volts between each phase. The current NEC requires the high leg to be the B phase bus in switchboards and panel boards. BUT it once was required to the C Phase bus at the far right of the panel.
+3beltwesty Another train of thought is the Utility always have kept the high leg (stinger, wild leg, red leg) on the C phase.
+3beltwesty Another train of thought is the Utility always have kept the high leg (stinger, wild leg, red leg) on the C phase.
Thanks for the explanation of the voltages between the phases. I now have a better understanding of the legs in a 3 phase system. cheers.
What if you have a three phase ac motor with no neutral? How would you check to see if the leads are live?
Measure phase to phase, in a 120/240 system you'd have 240 between phases.
I would have liked to seen the voltage between a and c....
I like the video. I guess there's no way to tell if the A and C legs are reversed?? Since they are both approx 120 or is the 243 volts and 235 volts between A and B and B and C the way you would tell?? Thanks...
Does not matter if they are reversed, essentially they put out exactly the same thing, 120V single phase.
I have 3 phase panel a,b is 120 and C leg is 220 i like to replace only bas bar .if i get same brand panel instead changing hall panel can i only change bas bar thanks
Your high keg should be on B phase, but I would not recommend swapping it. If you change out your panel make sure no single pole breakers get installed on your high leg
Snot rocket man in the Background, too funny
I have a meter main with three hot lines. They are 120v, 120v and 213v. Does that mean I have a three phase 208v. panel?
No you have 120/240v 3phase 4 wire. 213 is your high leg and is not used for single phase loads.
Thank you
The panel box is labeled correctly. By removing that orange tape on the B phase, you are held liable. If you were to open the transformer, you would see on the secondary side PHASE A=BLACK
PHASE B=ORANGE, not red
PHASE C=BLUE
He didn’t remove it, he said he’s the one who put the orange tape.
What is a Highleg?
So have an existing panel that is reading 123 on both A and B phase but for some reason C phase is showing 216.
The panel is supposed to be set up for commercial A/C’s with two 70 amp 3 phase breakers.
Any ideas??
Split delta flying high leg?
In that case based on your readings you have a 120/240V 3ø 4w system, and the high leg is terminated on the C phase. In installations before 1975, this was typically the case, but after 1975 the high leg should have been terminated on phase B. High leg should be orange, and regardless of the panels you should always verify with a meter before connecting stuff. Do not rely on colors or labels.
How can I connect a 3-phase electric wires to the A/C compressor?????
Screwdriver. Use it to loosen and tighten the screws.
Three phase motors low voltage use any ucupment
Just want to make always check for high leg on 3 phase system.
I was checking a 3 phase system and I got 120 120 120 to neutral. What is going on
This is a 3 phase delta (high leg)system. Voltages are 120/208/240. You most likely are dealing with a 120/208 wye system. Phase to phase should give you 208 and each phase to neutral will give you 120. It has to do with the configuration of the transformer. Hopefully this helps
So the one measurement you didn't show was the voltage between A&C is that going to be 208 or 240?
Rod Bower it'll be 240 volts rms phase to phase
In 3-phase all 3 phases should reference the same voltage to each other, the difference comes when you neutral reference things
Can i have a 3 phase elec. Connection and have a 1 phase package unit ?
Yes
Brown yellow and orange are 480 volt 3-phase leg blue red and black are 120 208 volt 3-phase leg colors .
3 phase delta systems have a High leg and it is marked orange, 3 phase Y systems use black red and blue.
thanks
Thanks
A stupid question: how to find A and C ?
Not 120/208. It is a delta 120/240 with a power leg of 208. And the power leg should be connected to “c” phase.
You should be wearing ppe equipment to be within the electrical code . Arc flash clothing
Grace, Mercy and Peace to you all
If you had measured all three phases against each other and if you got 208volts and 120volts from neutral to each line then it would've been a 120/208Y system
I can't see how u get 208v from hot to neutral I service In ny and it's usually 123 to ground on each phase 208/240 between each phase 123 or abc so again huh
Your three phase service is a WYE type of service, and his is not. His is also known as a high-leg or wild-leg delta system. That's why there is a 208V from high leg to neutral.
Vectors Baby!
What is the point of a high leg?
208 volts to ground is not an intended voltage in this application, it just happens to be a byproduct of the transformer configuration. The typical application for this type of service would be in commercial or industrial settings where the majority of the loads are 3 phase motors, with a small amount of 120V loads. Typically these systems are found in older buildings in rual areas, you rarely see them being installed as new systems.
Con madre. Cuál es tu número. De teléfono yo kiero ser journeyman
120 volts on A and C phase. Thanks for your comment.
It’s not banned!!!
Why do we have different voltages and phases all over the world, maybe there should be a standard? Thanks for your comment, I like Hearing from my friends across the pond.
There are lots of standards, primarily managed by the IEEE.
As for one common global one? Blame George Westinghouse, Thomas Edison, and Nikola Tesla for inventing electricity in America before the internet would have allowed them to readily share (and license) their specific approaches to lighting, motors, transformers, generation, transmission, and distribution.
Mohammed Ali hadn't been born yet to create the Butterfly Effect.
same as 230V at singlephase and 400V 3 phase you have 50hz system colours --> phase 1 brown phase 2 black 3 gray 0 blue ground yellowgreen at eu
Antsa15 That's European color markings on 3.phase.
What if you dont have high leg? My all legs are 130..
high leg only occurs in delta config. If all legs are 130, you are running a wye config.
@@elena6516 hahha 10 months ago. I already figured out! May your comment might help someone!
How is the potential difference between phase A and phase B 240V when it is 208V between Phase A and neutral?
question from a 1st year electrician
Phase B to ground is 208 because it's a 120/240 3 phase delta. You'll have 240v between any two phases. Phase a and c will be 120v and phase b will be 208v. Simply put, phase b has to travel the furthest distance to the nuetral in this delta system. If you take the square root of 3 (1.732) and times it by your line to nuetral voltage(120v) of phase a or c, that's how you get 208v.
Alex Millison Or you can simply multiply 240 (hypotenuse) × sin(60°) 0.86623~ 208
Jolyon Welsh or you can take 120V times the square root of 3 (1.732) which equals 208.
0.86623 =√3/2
Correct
Hi Mr Jones, I dont have good knowledge in electricity, just curious asking, does it dangerous using the multimeter to measure the voltage like what you did ?
anything i need to be aware?
ELFYHO if you don't know what you're doing. if you're not an electrician or have a working knowledge of electricity don't do it. you don't get second chances with electricity
Omg 3 phase wiring is so much simpler in NZ than the USA. We have L1, L2, L3 + N and + E Red , White , Blue, Black , Green/Yellow sometimes with out the Earth or sometimes with the Earth and not the Natural
Same as South Africa
If we did a high leg like theirs, we would still have 400v phase to phase, but we would get 230v phase to neutral on the "high leg" and 200v phase to neutral on the other two.
We don't bother, we just go 230v/400v.
Phase B is not required to be the high-leg, any phase can be high-leg as long as it is permanently marked (NEC Article 110.15)
You may wish to read 408.3(E)
@@jjoejones1 Thank you and I just did. You are correct for NEW installations, but there's an exception for additions to EXISTING installations so my original comment can hold true. B phase high leg would in most cases be required per code and conforms to industry standard, so it is best practice.
@@nickesposito3497 as an electrician myself, we have the golden rule: don't trust colors, trust your meter. And always wear your PPE when probing inside a live panel.
Very informative video. The only thing I can see the high leg being good for is lighting where you have a ballast that can run on 120-277V. 208V has always been a mystery to me.
+Daniel Peters The voltage between all three phases is 240V. It is only to ground that the high leg is 208V. Three phase devices rated for 240V can be connected A,B,C while split phase 240V devices can be connected across the two 120V legs and single phase 120V devices can be connected between either 120V leg to neutral. You just cannot connect a 120V single phase between the high leg and neutral.
Orange is what is supposed to be marked on the highleg wire.
Good explanation Dave
If you can take some constructive criticism, I'll bet 5 dollars against a stale donunt there is probably 6000 amperes at that buss all ready to burn hide and meat through an arc-flash along with plasma particles to be injested when something goes wrong and the planets all line up. As an inspector if I observed someone doing this at a mine I would be obligated to issue and imminent danger order along with a citation that could cost in the 5 digit category. Other than that I'm a fan for sure.
Bob
Agree. No PPE, but 208V high leg isnt likely to arc flash like 480V will. 6kA fault current is probably low. He also didnt check A-C phase, tho it's likely 240V given his other readings.
Never see delta here on the conditions that I seem to work in. Everything supplied here is Wye.
In order to understand this condition you gave us some voltages but not all the voltages.
you gave us
A - N 121v
B - N 208v
C - N 122v
N - Gnd 0v
and
A - B 243v
B - C 235v
but no
A - C
So the give away here for the delta connection is the high leg AND the 240ish voltage?
So what is the low leg to low leg A - C voltage? 243ish 235ish or 208v?
Also is my assumption that there are no 120v loads on the B phase to N at all in that panel?
Nice upstaging job by your assistant. :)
I just found an explanation that complements your demonstration. Thanks again.
watch?v=S1DUe_HQKtQ
Interesting stuff David!
Our power here is 240V to neutral single phase or 415V between each of the three phases, there is no high leg.
In some rural areas there a few split phase 480V two phase supplies but hey are still 240V to neutral just that the phases are 180' out instead of 120' as in three phase.
If you ever have 240 to N, something is wrong. You can have 277 to N, 120 to N, or 220 to N (in European countries). You shouldn't find 240 to N anywhere. Although, you can definitely get 240 by measuring across two 120 phases in a single phase 3 wire system.
He's getting 240v to neutral since his line to line Y config is 415v. Line to line is 415v.
The right order to check the electrical installation: L1-L2, L1-L3, L1-N, L1-E, L2-L3, L2-N,L2-E, L3-N, L3-E, N-E.
PPE folks, always.
Just because you wire you more ABC, does not guarantee you'll get the rotation you want. You have no idea what rotation the utility provider is giving you. They switch A and C phase because the utility power is the opposite rotation they need
true
You want people to follow NEC, but you don't follow OSHA by not wearing PPE.
Your the guy no one likes working with 100%
B phase of delta high leg must be tagged orange...nec 110.15. you finna make somebody blow they shit up.
what if you get 120v on all 3 phases
Then it's a 120V/208 3 phase wye system. This is not a 120v/208 system. This is a 120/240 3 phase delta.
Alex Millison. so i could not get 240v so i just ran the air at 2o8v but it worked
birdchaser2010 most motors will say on the nameplate if they can operate on 208V. if it's a 240V appliance that has a fixed resistance like a heater, it's perfectly fine to run 208v to it. it'll just draw a little less current and not produce as much heat.
Alex Millison. it did say that
Alex Millison That is why I call it the wimpy wye system.
Your the tallest guy I’ve ever seen
No PPE, fail. Meter leads not both in one hand, sometimes required but never recommended. Do try to avoid setting up a situation where the current path is thru your heart if something should go wrong.
I had a customer steal my phase rotation indicator on me. @&%$*&!!!
I have always been taught to call it a "wild leg"
First you put on your ppe
thought the wild leg aways went far right.
You do know that this system is banned nec.1977.
Can you provide the NEC reference that ‘banned’ 240-volt, 4-wire Delta systems…..I think you’ll find you’re wrong.
@@jjoejones1 I think what willie isacz might have been referring to when banned, is what they called a delta breaker, that was used in a single phase panel to power one three phase load, typically in that era a 5 ton air conditioning unit. Most people probably have never seen a delta breaker or know that it existed, because it is a very oddball type. But yes 120/240 3ø4w is still allowed and sometimes still used in new installs, but is not nearly as common now as is was, say in the 50s and 60s. A common giveaway is 3 transformers on the pole, one of which is significantly larger than the other two. Another strong clue is in the panels with single pole breakers, every 3rd breaker opening is not used. These installs in this day and age really are kind of pointless, but you will run into them on different occasions.
@@Sparky-ww5re Thank you for your reply. I am familiar with Delta breakers but when Willie used the word ‘system’ in his comment, it did not appear he was referring to delta breakers. Regarding the transformer configuration for a 3-phase, 4-wire Delta. In my area it is more commonly seen as an ‘open’ delta which only requires (2) transformers as opposed to the ‘closed’ delta which requires (3) transformers.
The title should be "guy wearing golf shorts and wire rim glasses who doesn't know 3 phase from split single phase takes dumb risks in live panel with bare hands and hunts around with a meter trying to get an instant suntan" . This video should be taken down.
Wow no flash gear 😖, dancing with the devil there.
flash gear on 120/208? Do you wear flash gear when plugging in your vacuum or refrigerator at home?
good video except for guy blowing snot in background