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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: John Fruits on February 02, 2014, 05:50:07 PM
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I was somewhat curious that different names exist for the three hot legs in three phase power. The ones I have seen are
X,Y and Z
A,B and C
H1,H2 and H3
L1,L2 and L3
I was wondering if there was any reasoning behind this or is it perhaps a regional thing.
Incorrect answers:
Half a hot time for ZZ Top
Curly, Larry and Moe.
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I was somewhat curious that different names exist for the three hot legs in three phase power. The ones I have seen are
X,Y and Z
A,B and C
H1,H2 and H3
L1,L2 and L3
I was wondering if there was any reasoning behind this or is it perhaps a regional thing.
Incorrect answers:
Half a hot time for ZZ Top
Curly, Larry and Moe.
I use X, Y and Z, but just cos that is what is labeled on the cable ends...
Ray
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I use X, Y and Z, but just cos that is what is labeled on the cable ends...
Ray
We used L1, L2 and L3 for industrial wiring ladder diagrams. Also marked 3-phase power with a 3P or 3/P
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I think it is more industry/equipment related. When working with power panels we usually refer to A phase-B phase-C phase. On some CNC equipment and VFDs you might see U,V,W and R,S,T depending in input/output. Three phase transformers are usually marked H1, H2, H3 and X1, X2, X3 for primary and secondary respectively (if there is an X0 it would be the neutral.) As Mike noted, L1,L2,L3 is common on industrial diagrams and line side of contactors-T1,T2,T3 on the motor side.
I am sure there is probably a NEMA or industry standard somewhere-seems to be too consistent to just be the random preference of the design engineer-though there are a few that seem determined to be creative!
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L1, L2 and L3 over here.
Steve.
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Since we are generally dealing with Cams we call them Red, Black and Blue.
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Since we are generally dealing with Cams we call them Red, Black and Blue.
Just be careful if you go to Australia or New Zealand.
http://en.wikipedia.org/wiki/Electrical_wiring
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Just be careful if you go to Australia or New Zealand.
http://en.wikipedia.org/wiki/Electrical_wiring
Also in America be careful if you see anything in a 3-phase panel with orange tape on a wire. That's likely a High-Leg Delta service (also called Wild-Leg Delta or Red-Leg Delta). This was found in older industrial buildings that needed mostly 3-phase 240-volt power for motors, and limited amounts of split-phase 120/240-volt power for offices. Note that the Orange High-Leg have 208-volts to neutral, instead of the 120-volts to neutral of the other two legs. Of course, connecting 208 volts to anything expecting 120 volts will make for a very bad day.
See http://en.wikipedia.org/wiki/High-leg_delta for a good tutorial on how this all works.
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Also in America be careful if you see anything in a 3-phase panel with orange tape on a wire. That's likely a High-Leg Delta service (also called Wild-Leg Delta or Red-Leg Delta). This was found in older industrial buildings that needed mostly 3-phase 240-volt power for motors, and limited amounts of split-phase 120/240-volt power for offices. Note that the Orange High-Leg have 208-volts to neutral, instead of the 120-volts to neutral of the other two legs. Of course, connecting 208 volts to anything expecting 120 volts will make for a very bad day.
My understanding is that 208V (pole to neutral) is used mostly for fluorescent lighting loads and occasionally for heating loads. This allows for a single-pole 20A circuit providing 3328VA versus 1920VA of lighting on a 120V circuit. Therefore, you can have more lights on a single switch. The advantage of 208V over 240V is that 240V is double-pole, requiring double-pole breakers and switches.
(Note on the math: while a 208V 20A circuit has a capacity of 4160VA, code requires limiting a continuous load to 80% of the circuit capacity. That's how I get 3328VA.)
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Disregard.......
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Code requires different voltage systems in a building to be identified by color scheme. Around here, typically, we use black/red/blue for 208/204 3 phase and brown/orange/yellow for 480 V 3 phase-so if you see orange make sure what you are dealing with. (Also, ideally 277/480V should use a gray neutral to distinguish.) High leg can be either open or closed delta. My understanding is that especially open delta has poor voltage regulation and the high leg to N should never be used. I have only ever used the high leg on 3 phase loads-that is what it is intended for and the safe way to use it.
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eenie, meenie, minie....
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eenie, meenie, minie....
Kaboom!!
Steve.
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Ow!
Ow!
Ow!
Ground. :-D
Much like my circuit tracer. When I hear the high pitched noise, I know I've turned on the breaker to the outlet he's holding.
(I kid of course, it's actually a visual indication based on how high he jumps)
No offense, the topic title really does sound like a setup for a very bad, un-PC joke...
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No offense, the topic title really does sound like a setup for a very bad, un-PC joke...
I was looking for a picture of a female alien triped without success.
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I was looking for a picture of a female alien triped without success.
I did find a hot 3-legged chick....
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In Nashville, were 'famous' for our Hot Chicken. Maybe if they started using 3 legged chicks...hmmm.
- Tony Williams
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In Nashville, we're 'famous' for our Hot Chicken. Maybe if they started using 3 legged chicks...hmmm.
- Tony Williams
Less fighting over who gets the drumsticks....
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In Nashville, were 'famous' for our Hot Chicken. Maybe if they started using 3 legged chicks...hmmm.
- Tony Williams
Tony, I may be driving thru Nashville early June. Let me know where to try one of those hot 3-legged chicken meals. Yum 8)
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Tony, I may be driving thru Nashville early June. Let me know where to try one of those hot 3-legged chicken meals. Yum 8)
Prince's hot chicken is the famous one. There's about 10 other restaurants that basically copy them.
en.wikipedia.org/wiki/Hot_chicken
- Tony Williams
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Prince's hot chicken is the famous one. There's about 10 other restaurants that basically copy them.
en.wikipedia.org/wiki/Hot_chicken
- Tony Williams
Tony, that looks disgustingly delicious ;D
Seriously, I'm going to try out Prince's Hot Chicken on my next drive through Nashville. I'll give you shout when I'm going to be in the area, and if you're available I'll even buy us both dinner.
Now, back on topic... :o
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Tony, I may be driving thru Nashville early June. Let me know where to try one of those hot 3-legged chicken meals. Yum 8)
They haven't been able to catch one yet.
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They haven't been able to catch one yet.
It's crossing the road... ;)
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I just did a tech gig near Washington DC today, and one of the sound guys said he was raised in Nashville. So I told him that I was going to try Prince's Hot Chicken the next time I was in town. He got a little uppity with me and demanded to know how a Yankee knew about Prince's Hot Chicken. >:(
So is Nashville Hot Chicken a big secret from northerners, or what? Yes, I'm from Maryland and south of the Mason-Dixon line, but I thought that border states were exempt. :o
Who knew that a topic named "Three Hot Legs" could produce such a response...
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I just did a tech gig near Washington DC today, and one of the sound guys said he was raised in Nashville. So I told him that I was going to try Prince's Hot Chicken the next time I was in town. He got a little uppity with me and demanded to know how a Yankee knew about Prince's Hot Chicken. >:(
So is Nashville Hot Chicken a big secret from northerners, or what? Yes, I'm from Maryland and south of the Mason-Dixon line, but I thought that border states were exempt. :o
Who knew that a topic named "Three Hot Legs" could produce such a response...
Haha, we Nashvillians are a strange bunch.
- Tony Williams
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Haha, we Nashvillians are a strange bunch.
So if you turn bad, do they call you Nash-villains? :o
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Haha, we Nashvillians are a strange bunch.
- Tony Williams
Hey Tony (and any other Nashvillians),
Looks like I'll be driving through Nashville on my way to San Diego on May 14th or 15th, and could meet you for some Prince's Hot Chicken. I'm buying, so let me know if you're available for lunch or diner and we'll see what all the brew-ha-ha is all about. 8)
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Hey Tony (and any other Nashvillians),
Looks like I'll be driving through Nashville on my way to San Diego on May 14th or 15th, and could meet you for some Prince's Hot Chicken. I'm buying, so let me know if you're available for lunch or diner and we'll see what all the brew-ha-ha is all about. 8)
Update: I'll be in Nashville Wednesday evening, April 9th. Anybody want to meet me at Prince's for Hot Chicken?
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in a transformer on the lug bus its labeled > L for the 120 side and H for the 480 side. XO is for the neutral. A=Black for 120 - Brown for 277 , B=Red for 120 - Orange for 277 , C=Blue - Yellow for 277. White is ALWAYS Neutral , Green is ALWAYS Ground. NEVER NEVER NEVER assume that GRAY is a Neutral. some idiots started using Gray for the Neutral on 277V lighting circuts. I have seen Gray used MANY times as a hot leg with a White Neutral. NATURAL GRAY in the code book refers to an old "Off White" color and Not the color Gray. an inspector made a crew pull All the Gray wire out of a 277 lighting circut and pull white back in for the Neutral. I never pulled Gray for Neutral , I always use White. My inspectors were Always happy with me for that. L also stands for Low gear in my F350 with a stick shift. I'm feeling might L right now !
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The problem with using white for all neutrals is that the neutral for a 277 system is not he same as a neutral for a separately derived (transformer) 208 system. I am dealing with a building now where a previous contractor ran both 277 V and 120 V lighting circuits in the same conduit. If I cross a neutral in a box, I wind up with the current from the 120 V system getting back to the 277 V neutral via the associated bonding-not a good situation. Code does require identifying neutrals from different systems by using a white wire with a stripe-they can be pretty hard to find.
It seems like using gray has been a common industry practice, even though Jeff is right. Interestingly, a code panel rejected allowing gray to be used because it felt that white and gray would not always be distinguishable in the same box. That reasoning would seem to preclude using gray as a hot conductor as well, but what do I know?
Update:
Actually just looked at the 2011 NEC. The term "natural gray" is no longer used. The 2011 NEC specifically allows Conductors with 200.6 (A) (1)"A continuous white outer finish" and 200.6 (A)(1) "A continuous gray outer finish" to identify a neutral.
NEC 200.7 specifically prohibits using a conductor with a "gray covering" from being used as a hot.
The other discussions regarding a read about took place at least 4 code cycles ago. I am still using the 2011. 2014 is "out" but not being used yet where I am.
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The problem with using white for all neutrals is that the neutral for a 277 system is not he same as a neutral for a separately derived (transformer) 208 system. I am dealing with a building now where a previous contractor ran both 277 V and 120 V lighting circuits in the same conduit. If I cross a neutral in a box, I wind up with the current from the 120 V system getting back to the 277 V neutral via the associated bonding-not a good situation. Code does require identifying neutrals from different systems by using a white wire with a stripe-they can be pretty hard to find.
It seems like using gray has been a common industry practice, even though Jeff is right. Interestingly, a code panel rejected allowing gray to be used because it felt that white and gray would not always be distinguishable in the same box. That reasoning would seem to preclude using gray as a hot conductor as well, but what do I know?
Update:
Actually just looked at the 2011 NEC. The term "natural gray" is no longer used. The 2011 NEC specifically allows Conductors with 200.6 (A) (1)"A continuous white outer finish" and 200.6 (A)(1) "A continuous gray outer finish" to identify a neutral.
NEC 200.7 specifically prohibits using a conductor with a "gray covering" from being used as a hot.
The other discussions regarding a read about took place at least 4 code cycles ago. I am still using the 2011. 2014 is "out" but not being used yet where I am.
its illegal to run 2 different power voltages in the same condiut. i have never seen or heard of it done. you would need to come out of the 480/277 panel into a gutter or pull can and also come out of the 120/208(240) panel into the same gutter. now your mixing voltages which is illegal. 2 phases of 277 in the same can and condiut is 480v. brown,orange,yellow wire is use for 277/480 with black,red,blue,purple,pink used for switch legs. someone doing service/add-on work could tie a 120v recptical into a 277 leg. i'v seen a lot of illegal stuff done but never mixed voltages. many many years ago in downtown los angeles GREEN was use as a hot leg in some buildings. i found out the hard way. also i was talking to an electrician friend earlier today and he did some work on an old house with black pipe that had gray for the hot and white for the neutral, no ground wire. old plugs with no ground hole.
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I would agree that mixing different voltage systems is poor practice-and I wish it would not have been done this way. However code specifically states that neutrals from different systems in the same raceway or box must be identified. In most cases different systems would mean different voltages-this would seem to indicate that it is allowable-I am not trying to argue, I would like to know the code reference, I just haven't found it yet.
If someone is tying in a receptacle, I would hope they shut off the breaker-and if working in a facility with 480/277 I would hope they would recognize the difference between a 120/208 breaker and a 480/277 breaker and hopefully the panels are marked, too. Good workmanship also says to test that receptacle when done and verify that it is right-that should prevent a problem.
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I would agree that mixing different voltage systems is poor practice-and I wish it would not have been done this way. However code specifically states that neutrals from different systems in the same raceway or box must be identified. In most cases different systems would mean different voltages-this would seem to indicate that it is allowable-I am not trying to argue, I would like to know the code reference, I just haven't found it yet.
Another weird one to consider is 4-wire/3-phase wild/high/red/bitch-leg Delta, typically with 120, 240 and 208 volts available on the same wires in the same panel, just depends on how you hook up which phase(s). Of course the "high" leg is supposed to be marked with "orange" tape in the panel, but I don't know if that translates to a different wire color downstream. This was common in older 3-phase factory power from the 50's and 60's IIRC, but I've found it a few times in repurposed industrial buildings that have been turned into concert venues, clubs, and churches. Measure twice / connect once. See http://en.wikipedia.org/wiki/High-leg_delta (http://en.wikipedia.org/wiki/High-leg_delta) for a primer.
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I would agree that mixing different voltage systems is poor practice-and I wish it would not have been done this way. However code specifically states that neutrals from different systems in the same raceway or box must be identified. In most cases different systems would mean different voltages-this would seem to indicate that it is allowable-I am not trying to argue, I would like to know the code reference, I just haven't found it yet.
If someone is tying in a receptacle, I would hope they shut off the breaker-and if working in a facility with 480/277 I would hope they would recognize the difference between a 120/208 breaker and a 480/277 breaker and hopefully the panels are marked, too. Good workmanship also says to test that receptacle when done and verify that it is right-that should prevent a problem.
nope , cannot mix voltages. if your called to install a receptical on a wall with a tigerbox and you have a j-box with 277v lighting and 120v recepticals you cannot shut off those lightining circuts and leave people in the dark. i have come across many j-boxes that were not labeled and with wires that were not numbered and with 2 or 3 different neutrals. the business didnt have a set of as-builts or prints. i have also seen black red blue wire used in 277 systems in coundiut. i have done quite a few of these recepticals and was only allowed in the business/office building during work hours. i have move desk and removed t-bar tile with the employee(s) going about their work with me in there. i left a message with the local senior inspector to call me about this one. but everything i'v ever learned is you cannot mix 120 and 277 in the same condiut.
p.s. about 20 years ago i came across an unlabeled j-box with a blue/white on one side connected to a yelow/white on the other side. i never did find where it went. it was a large 4 story building.
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Another weird one to consider is 4-wire/3-phase wild/high/red/bitch-leg Delta, typically with 120, 240 and 208 volts available on the same wires in the same panel, just depends on how you hook up which phase(s). Of course the "high" leg is supposed to be marked with "orange" tape in the panel, but I don't know if that translates to a different wire color downstream. This was common in older 3-phase factory power from the 50's and 60's IIRC, but I've found it a few times in repurposed industrial buildings that have been turned into concert venues, clubs, and churches. Measure twice / connect once. See http://en.wikipedia.org/wiki/High-leg_delta (http://en.wikipedia.org/wiki/High-leg_delta) for a primer.
the "kicker leg" as some of us call it must be an orange wire or marked with orange phase tape if its larger than #6. in california the kicker leg is C phase at the service and then goes to B phase at the breaker panel. i think thats stupid but its the way cali does it. theres lots and lots of 120/240 3 phase 4 wire systems here in los angeles. newer areas get 120/208 3 phase 4 wire sytems but it seems the 120/240 is the dominant one. a friend owned a building about 100 years old in Pomona. i rewired it for him. it had 2 seperate services. a 120/220 single phase 3 wire service and straight 240 3 phase 3 wire system for compressors, air cond , etc. no neutral for the 240 system. i was looking at the ;power pole and the 240 service ended at his building.
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I rarely trace wires back to ID a breaker-most of the time j-boxes are unmarked. Breaker panels should be marked with voltage and breakers should be marked, but over time the markings become less reliable as work is done and things are changed. Mike gave a great idea for IDing a circuit without turning it off in another thread.
NFPA 70E deals with arc flash and energized work-ie installed recepts on an energized circuit. One tool it gives electricians is a requirement that before energized work is done, a "Hot" or "Energized" work is done a permit must be filled out. There is something about requiring management to justify not turning off a circuit AND signing their name to a permit that spells out the potential dangers that often facilitates a change of heart about not shutting off that circuit for a few minutes so work can be done safely. A company policy to that effect might come in handy on some jobs.
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Based on the title of this thread, I was thinking maybe a new and really twisted Rod Stewart song.
Geri O
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It sounds like the whole of the power distribution system in the US needs to be scrapped and you should use a simple system like ours!
Steve.
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It sounds like the whole of the power distribution system in the US needs to be scrapped and you should use a simple system like ours!
Steve.
As I've noted before, the US was the original test-bed for power distribution via inventions from Edison and Tesla, so a lot of early power was bleeding edge. There were numerous band-aids applied to early power systems to avoid the expense of starting over, which has created a plethora of wiring strategies in the US, many still in operation today. At least we've finalized on 60 Hz here and 50 Hz in much of Europe. But there were a bunch of different frequencies tried, starting with 25 Hz generators at Niagra Falls. See charts below. Talk about some strange sounding "hum".
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At least we've finalized on 60 Hz here and 50 Hz in much of Europe. But there were a bunch of different frequencies tried, starting with 25 Hz generators at Niagra Falls.
I have seen old advertisements for Gibson amplifiers with a 25Hz (more likely 25c/s) option.
Steve.
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It sounds like the whole of the power distribution system in the US needs to be scrapped and you should use a simple system like ours!
Steve.
I am not sure that would help-the system works fine as long as you make an effort to learn it and do things properly. The problem is people that think "anybody can hook up wires, its simple". It is easy and anybody can-if they take a few minutes to learn.
A customer had an employee (presumably one who "knew" wiring) wire up a simple add-on j-box on an industrial material handler earlier this week. Ten wires, 4 white with a number 2 on them, 2 red with a number 3 on them, a couple red and a black with a 29, and an oddball black with another number. Anyone who has been around industrial controls knows all you had to do was match the numbers-and for sure all the whites would go together. They had me check it before they tried it. Not to be mean, but I could have come as close to right as he did with my eyes closed.
How would remaking the system fix that kind of stuff? I have a great deal of respect for someone who says, "I don't know" and asks someone who knows. I used to try to do everything myself. The older I get, the more inclined I am to defer to someone else in various areas. Laziness-or wisdom?
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I am not sure that would help-the system works fine as long as you make an effort to learn it and do things properly. The problem is people that think "anybody can hook up wires, its simple". It is easy and anybody can-if they take a few minutes to learn.
Quite true - but the beauty of our system is its simplicity. You can either have one phase and neutral at 230 volts or all three phases at 415 volts... that's it... no other options.
Steve.
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It sounds like the whole of the power distribution system in the US needs to be scrapped and you should use a simple system like ours!
Steve.
Two words: installed base.
The expense of scrapping an entire system to make everything match the Euro standard would be immense, and few people would be willing to accept the cost. Just look at the conversion to metric in the US.
The truth is, we ARE standardizing. It just takes a long time, and rather than obsoleting perfectly good stuff, we just phase it out as it dies. Over a hundred years into the project so far, another hundred or few to go.
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It sounds like the whole of the power distribution system in the US needs to be scrapped and you should use a simple system like ours!
Steve.
the cost would exceed the 17+ trillion national debt. i am a commercial electrician. its not an issue.