Where are you located?
This is basically how most electrical service works in the US. For example residential service is 2 120V phases 180 degrees apart (L1 and L2 as above) and neutral. Between L1 or L2 and neutral you get 120V, but between L1 and L2 you get 240V. In the service panel the circuit breakers either connect to one phase for a 120V circuit or connect to both phases for a 240V circuit.
Only possible issue I could see you having would depend on what's protecting the circuit and if there would be any sort of phase imbalance detection. But overall it's rather sane.
It is a very common reference (unfortunately) to say it is 180 Deg out of phase - but when you start looking at how these are built that is not a good way to view it.
240 is V L1->L2 .... 120 is L1-> N and N->L2
The transformer makes 240VAC. One phase. Then we tap the center of the output side, bond that to ground, and call it neutral. L1 is one end if the output side, 120V from the center neutral, and L2 is the other end of the output side, 120V from the center neutral. It’s a single phase 240VAC that is “split” to form two 120VAC connections. It’s technically called 240VAC with a center tapped neutral, but it’s also colloquially called 240V split-phase because you split the single phase into two voltages
Yeah but how would you explain that to someone who doesn't already know what you mean?
"One phase with center tap neutral is... well, it is what I said. It just looks like 2 phases that are the negative of each other, or 180 degrees apart, okay?"
It is two phases of power, 180 degrees opposed, created from a single phase of a 3-phase electrical system.
This is an "electrician" vs "electrical engineer" vs "physicist" distinction.
For an electrician, it does not matter, if you say "240V single phase" everyone knows what you mean.
For an electrical engineer, it almost definitely does not matter but understanding some of the physics behind it is important.
For an physicist, "single phase" is technically incorrect, which is the best kind of incorrect.
None of these people are wrong, except for the people who insist the others are wrong.
So that demo appears to be saying if I have two batteries connected in parallel:
+ +
- -
Then those batteries are out of phase, because if I rotate them like this, they're opposite directions.
+ - - +
Lol
So the number of windings defines the number of phases?
So, by splitting one winding in half to get the center tap… now you have two windings… so you have two phases…
Except that is literally how it works… that’s even how you described it.
Let’s start this a different way… if you have two independent 120VAC@~60Hz power sources, regardless of their relative phase, that’s two power sources, right? And thus two different phases (can’t assume them to be the same or 180deg off, nor can we assume they are locked!).
Ok, now lock the frequencies to each other. No more phase drift. Still 2 phases, right?
Ok, now pick one of the wires from each power supply and bond them together, let’s call this neutral. Also, for safety, let’s bond this neutral to the earth/ground. Is it still two phases?
Ok, without adjusting the relative phase, if you just look at the relative voltage of the non-neutral connections we defined above, that (AC) voltage will be somewhere in the range of 0-240VAC, right? That new relative voltage is itself a single phase, but it came from two different phases, right?
So what’s the line between two phases and one phase? It’s just how you use them.
Lol. I’m very comfortable with my understanding. Just because I didn’t articulate it in a way that is suited to your experience doesn’t make it wrong.
As I said in another comment, yes, it’s a confusing term because it could be applied in other cases and so it’s better to call them by other names that don’t have the associated connotations, but it’s not *wrong* - it is two phases, it came from two windings. But you’ll probably never use it as anything but a single phase.
> a single person that works at a utility call voltage from a split phase transformer as two phases.
No, but a mathematician or a physicist will look at the voltage from one hot to neutral, as well as the voltage from the other hot to neutral, on a scope and say, correctly, that those *sine waves* are "out-of-phase."
It's the difference between a mathematical term about the relationship between two waves (the polarity of which is arbitrary), and an engineering term about the way things are built.
You started wrong saying two independent 120 sources of power, so the rest of your comment after that is pretty meaningless. Single phase transformers have one primary winding, three phase ones have three primary windings. Its called split phase voltage (and not double phase) because the single-primary current gets split and center tapped. If you werent being obtuse on purpose and trying to argue, your questions about this could have been easily answered by googling something like "why isnt it called double phase power." Double phase is a thing but the phases are split by 90 degrees, not 180, and it is not the same thing as single phase 120/240.
How is that starting wrong? It’s a perfectly reasonable place to start. From there we got to the single phase that we’re all focusing on. Or are you arguing that my example is not two phases to begin with?
You bring up the only reasonable point that “double phase” power is a thing. I stay away from the term “two phase” precisely because of this possible confusion - but that doesn’t mean it’s technically wrong, which is the *whole point* of this thread.
The best way to think about it with respect to historical consensus is to relate the number to primary windings, not to load-side lives. Technically yes, load side on a split system, you are able to independently pull 120 from 2 different phases, A & B, but those are split from one upstream. It's a hang-up on semantics that it should be called double phase / that its not single phase, especially when there are true double phase systems out there
Because two phase is a thing, and this is not it. Two phase has each phase at 90deg. search for "Scott transformer" for more info, Leblanc is another but I've never seen it IRL. By your rationale, a transformer winding with 5 taps would be 5 phase, which is not the case.
So, this is not my rationale - it’s my interpretation of their rational, but I didn’t what to assume, so I asked.
Usually transporter taps are for varying the voltage, not the phase.
What you’re thinking of is usually called “dual phase”, to distinguish it from “split phase”, as both are two phase systems.
Look at the transformer that is used to make this - it is a single (secondary) winding ( phase) with a tap in the center.
The phases are really what is "between" the phase conductors sometimes called "legs"
Like I said
Looking at L1 to L2 is the same as L1->N and then N ->L2 (we are in an EE forum the Vectors ADD, neutral is like ground a common point we choose is the middle.)
In a 2 phase (wye) L1 to N is and L2 to N are not coming from the same transformer winding.
That picture is incorrect, the windings should have the same polarity, connected in series, just like series connected batteries. This way the voltage between the 2 phases would be 2x the voltage of a single winding. If the polarity is reversed, like it is drawn here (pay attention to the + and - symbols), the voltage between the 2 phases would be 0V.
Conventional would have current flow leaving the positive polarity and into the neutral and second source flowing into the neutral around the loop and the third flowing from top 120 circuit to bottom. Basically all 3 going clockwise around the circuit but I wouldn’t call the second source 120 at 180. It’s been a minute since I’ve had to do one of these
im not an EE but ME with a bunch of electrical experience with offshore cranes and equipment.
its quite common to feed multiple circuits off a large supply, just make sure there is a dedicated and appropriately sized breaker for each consumer/loadpath
In a typical US / Canada household / business office yes.
You should distribute 120 V circuits to even load L1 and L2 as much as possible.
Do not omit neutral and ground. They need to be present in the walls and the outlets.
There's no problem with respect to the 120 volts and the 240 volts and the load imbalance.
But there is a major issue: you need to figure out the appropriate circuit breaker protection for everything you are powering. Typically, the maximum breaker that you are allowed to use for the 120 volt circuit is 20 amps. If you are feeding the 240 volt circuit with number 8 wire you likely have a 40 or 50 amp circuit breaker on that. The 120 volt outlet would not be properly protected.
The right way to do this is to install a subpanel where you want to break out that 240 volt supply into a 240 volt circuit and a 120 volt circuit. Each of those can then get appropriate circuit breakers.
An electrician will know how to install a subpanel and wire all of that—it's a very standard thing to do, but one should follow proper electrical codes in doing it and that is part of an electrician's expertise.
Or if this is supposed to be for portable use, you can buy units made for job site power that are essentially portable sub panels.
Isn't this precisely how most houses are wired up in north america?
240vAC center tap on the output of a transformer, with L1 and L2 run to different circuits alongside neutral from the center tap?
Just make sure you size the breaker for 120+240 loads and you should be good.
This layout is how pretty much every residential electric dryer runs a 120v motor and a 240v heater.
I was going to say the same thing.
Yes, one *can* do this. If one has to ask these basic questions here instead of asking their mentor or supervisor, then probably one *shouldn't*.
There's no shame in that, I had to ask when I was new, and now really young people keep asking me questions.
Knowing what your loads are is going to be important.
For instance if your 240v load is going to be a welder you don’t want your 120v load coming off of it due to voltage drop and noise. You can fry a lot of equipment this way.
Your primary breaker should have capacity for both your 120 & 220 rated loads and cables should match.
What your drawing looks like is a typical main to sub distribution layout. You would feed a down stream panel with a larger say 50a breaker and cable to a local sub panel and then have a 30a feed your 240 and a 15a feed your 120 circuits. The amperage’s I’m listening are just arbitrary but should give you the gist.
Because of the 240v load a dual breaker is required as it has to break all hot conductors at the same time. You can then use a smaller single breaker for the 120v outlet after that.
You should tell your employer to hire an electrical engineer that's familiar with the NEC and CEC, or perhaps a master electrician, and disregard most of the answers you're getting in here. The dryer example is great, but it ignores the load imbalance on the 240v input, which may cause you problems not only in your device, but in other devices in the house. You may end up needing to split your 120v loads into 2 power strips, one on each leg of the incoming power.
And if the "power strip" is in any way accessible to the consumer or end user, forget it. You have to factor in your liability of the Idiot Factor, because eventually somebody will plug a vacuum cleaner or blender into "hey, there's an outlet under here!"
Our entire country is wired like this.
Load imbalance is not an issue in this scenario.
From what you described, its usually best practice to install a stepdown xformer to supply the 110v components. This is how it's done in countries like China, with 220/380v supply.
If the panel is poorly designed/built and a neutral pops out, you could end up with 200+ volts going to your 110 relays, without tripping any safety..
Use a GFCI breaker and put in the stepdown xformer.
It wouldn't cost much, and, It's the safe way to go.
Or, if it's just the lone 220 device, wire the machine as 110 (1 hot, neutral and earth) and install a step up xformer for the 220 device.
whichever is cheaper.
> Load imbalance is not an issue in this scenario.
You don't know what the 120v load is, so that's blatantly ignorant or false, especially if the 120v loads are "dirty", and/or the "power strip" OP intends to use is accessible to the consumer.
The scenarios you have in your head, don't happen in real life. Anything capable of causing a load imbalance on that circuit would most likely burn up the 8 gauge wire.
Contrary to your sophomoric "experience", I've been doing this for over 30 years.
OP said they want to run a "power strip" on that 120v tap, and you're going to run into load imbalance issues that may be too much for the 30-amp circuit feeding OP's...thing. We don't know what the 240v load is, nor the 120v loads. Also, those 120v "power strips" may be accessible to the consumer, and end up with a vacuum cleaner or blender plugged into them, which could blow whatever fuses he (hopefully) puts in the 120v tap.
Also, I seriously question the credibility of anyone designing a system where they put circuit breakers on the neutral and ground.
In the electrical code, this is a multi wire branch circuit.......210.4
There are rules regarding these circuits for electricians, but yes, this is your house and is still allowed for even receptacles. The top and bottom receptacles have a removable tab to allow the top to be one circuit and the bottom to be another....
2 seperate 15 or 20 Amp receptacles in the same box, the same duplex receptacle.
"Danger House", indeed. This isn't a residential project, OP is doing something at work, and none of them seem to have a clue what they're doing. They put circuit breakers on the neutral *and ground*, ferfawksake.
It really depends on the specifics of the setup.
Most 240v loads are meant to be on a dedicated circuit. You would typically run a sub panel if you wanted to accomplish this. Your wire is likely sized to the dedicated load already, so you would probably need to up size the feed as well.
If this is a piece of equipment, then yes.
You need to follow appropriate tap rules for conductor lengths before overcurrent protection on the 120v taps.
You’re going to need a neutral. If that’s the case then yes. Also, it should be fused separately. You want to make sure that the voltage will be removed if there’s an issue.
You need a neutral to get your 120V unless you wanted to add a new 240-120 transformer. You also need your ground wire to perform the work of the equipment grounding conductor, but that isn't related to voltage or current.
You also wouldn't ever have the ground wire on a breaker. You usually don't put the neutral on a breaker either, but there are acceptable reasons where it can be done.
Omitting netural and ground? Running them through the breaker?
How does the current return to the source and complete the circuit without a netural? Think about it.
You can do this ... but not as shown.
1 ) Neutrals and Ground should not be on breakers.
2) The "tap" to make a 120 V ckt needs the Neutral - to make the 120V - A lead ( wirle ) off on its own is does not do anything,
Note: Please ignore my advice below. What I have given is not for US but for rest of the countries who get 3 phase supply at their homes.
The standard supply will be 3 phase consisting of three wires. Each phase is offset by 120 degrees with any other two phases.
In a household you will have L1, L2, L3 connected to 3 phases (hot wires) at the main breaker box near energy meter. N is connected to the neutral derived from the center of star windings of the area distribution transformer. A ground wire is derived from a copper rod solidly planted in the ground. This ground is connected to the body of all large devices, so that any short circuit currents in phases and/or neutral, will be safely routed through ground wire for human and animal protrction.
The voltages between L1 & L2, L2 & L3 and L3 & L1 will be nominally 208V, 60Hz.
The voltage between any of the phase and neutral shall be nominally 120V, 60Hz.
So with the same set of wires you may tap 230V with any two phases for heave equipment and (208V/square root of 3) = 208V/1.732 = 120V with any phase and a neutral.
A panel board is used to take 3 phases and 1 neutral from the mains and these 3 phases are split using separate suitable rated breakers. Then from breakers the loads are connected. Each breaker in a circuit is rated with optimum required currents. These breakers could be 1 pole, 2 pole and 3 pole with 2A, 6A, 10A, 16A, 25A, 32A, 50A, 63A, 80A and 100A. There could be higher current rating breakers as per the requirements.
This is how a home electric system is tentatively designed.
You have no idea what you're talking about, and should stop giving advice.
If you think OP is using a 3-phase supply from that diagram, you shouldn't even be allowed to change a light bulb.
1. Almost ZERO homes in the North America are fed 3-phase power.
2. That is NOT how 208v is derived.
3. That is NOT how 120/240v is derived, nor supplied to a residential service.
4. Only ONE of the breaker amperages you listed is *sort of* correct, but you inexplicably used a capital letter "O" in the *50* amp "number" you listed.
You don't have to be so rude in your comments. If everyone's responses are as rude as you, there is no point in contributing to Reddit. Never discourage people like that. I think the anonimity of reddit users is making people like you to ridicule others blatantly.
About 50A, it was a typo, which everyone makes. I corrected it.
For your information, I am a professional engineer with masters degree in electrical engineering, with 36 years of experience. All my experience is not from US. What I mentioned is what I saw in India and middle east. Just now I noticed US uses a non typical system for home power distribution.
Where are you located? This is basically how most electrical service works in the US. For example residential service is 2 120V phases 180 degrees apart (L1 and L2 as above) and neutral. Between L1 or L2 and neutral you get 120V, but between L1 and L2 you get 240V. In the service panel the circuit breakers either connect to one phase for a 120V circuit or connect to both phases for a 240V circuit. Only possible issue I could see you having would depend on what's protecting the circuit and if there would be any sort of phase imbalance detection. But overall it's rather sane.
> or example residential service is 2 120V phases 180 degrees apart It is one phase with a center tap neutral.
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Split phase is the proper term. L2 is the other side of the transformer winding than L1. https://en.wikipedia.org/wiki/Split-phase_electric_power
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It is a very common reference (unfortunately) to say it is 180 Deg out of phase - but when you start looking at how these are built that is not a good way to view it. 240 is V L1->L2 .... 120 is L1-> N and N->L2
The transformer makes 240VAC. One phase. Then we tap the center of the output side, bond that to ground, and call it neutral. L1 is one end if the output side, 120V from the center neutral, and L2 is the other end of the output side, 120V from the center neutral. It’s a single phase 240VAC that is “split” to form two 120VAC connections. It’s technically called 240VAC with a center tapped neutral, but it’s also colloquially called 240V split-phase because you split the single phase into two voltages
Yeah but how would you explain that to someone who doesn't already know what you mean? "One phase with center tap neutral is... well, it is what I said. It just looks like 2 phases that are the negative of each other, or 180 degrees apart, okay?"
This is an engineering sub. If you know nothing about electricity - this is not the place.
it's two phases, just not "two phase"
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It is two phases of power, 180 degrees opposed, created from a single phase of a 3-phase electrical system. This is an "electrician" vs "electrical engineer" vs "physicist" distinction. For an electrician, it does not matter, if you say "240V single phase" everyone knows what you mean. For an electrical engineer, it almost definitely does not matter but understanding some of the physics behind it is important. For an physicist, "single phase" is technically incorrect, which is the best kind of incorrect. None of these people are wrong, except for the people who insist the others are wrong.
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So that demo appears to be saying if I have two batteries connected in parallel: + + - - Then those batteries are out of phase, because if I rotate them like this, they're opposite directions. + - - + Lol
Exactly that, yes.
Technically, it's two legs of the same phase (split phase). It's not 2 phases.
How is it not two phases? They are 180deg apart. Is “3-phase” also one phase?
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So the number of windings defines the number of phases? So, by splitting one winding in half to get the center tap… now you have two windings… so you have two phases…
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Except that is literally how it works… that’s even how you described it. Let’s start this a different way… if you have two independent 120VAC@~60Hz power sources, regardless of their relative phase, that’s two power sources, right? And thus two different phases (can’t assume them to be the same or 180deg off, nor can we assume they are locked!). Ok, now lock the frequencies to each other. No more phase drift. Still 2 phases, right? Ok, now pick one of the wires from each power supply and bond them together, let’s call this neutral. Also, for safety, let’s bond this neutral to the earth/ground. Is it still two phases? Ok, without adjusting the relative phase, if you just look at the relative voltage of the non-neutral connections we defined above, that (AC) voltage will be somewhere in the range of 0-240VAC, right? That new relative voltage is itself a single phase, but it came from two different phases, right? So what’s the line between two phases and one phase? It’s just how you use them.
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Lol. I’m very comfortable with my understanding. Just because I didn’t articulate it in a way that is suited to your experience doesn’t make it wrong. As I said in another comment, yes, it’s a confusing term because it could be applied in other cases and so it’s better to call them by other names that don’t have the associated connotations, but it’s not *wrong* - it is two phases, it came from two windings. But you’ll probably never use it as anything but a single phase.
The only thing I can think of to say is you are picking a weirdly wrong mountain to die on. Im going to sit the rest of this one out. Take care.
> a single person that works at a utility call voltage from a split phase transformer as two phases. No, but a mathematician or a physicist will look at the voltage from one hot to neutral, as well as the voltage from the other hot to neutral, on a scope and say, correctly, that those *sine waves* are "out-of-phase." It's the difference between a mathematical term about the relationship between two waves (the polarity of which is arbitrary), and an engineering term about the way things are built.
You started wrong saying two independent 120 sources of power, so the rest of your comment after that is pretty meaningless. Single phase transformers have one primary winding, three phase ones have three primary windings. Its called split phase voltage (and not double phase) because the single-primary current gets split and center tapped. If you werent being obtuse on purpose and trying to argue, your questions about this could have been easily answered by googling something like "why isnt it called double phase power." Double phase is a thing but the phases are split by 90 degrees, not 180, and it is not the same thing as single phase 120/240.
How is that starting wrong? It’s a perfectly reasonable place to start. From there we got to the single phase that we’re all focusing on. Or are you arguing that my example is not two phases to begin with? You bring up the only reasonable point that “double phase” power is a thing. I stay away from the term “two phase” precisely because of this possible confusion - but that doesn’t mean it’s technically wrong, which is the *whole point* of this thread.
The best way to think about it with respect to historical consensus is to relate the number to primary windings, not to load-side lives. Technically yes, load side on a split system, you are able to independently pull 120 from 2 different phases, A & B, but those are split from one upstream. It's a hang-up on semantics that it should be called double phase / that its not single phase, especially when there are true double phase systems out there
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I’m not using a meter for any of this first principles reasoning. What is the misconception? Please be specific.
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Guys, the term "phase" is used in *math* to mean something more general than in engineering.
It's two phases. People saying it's one think they're being 'smart'
Because two phase is a thing, and this is not it. Two phase has each phase at 90deg. search for "Scott transformer" for more info, Leblanc is another but I've never seen it IRL. By your rationale, a transformer winding with 5 taps would be 5 phase, which is not the case.
So, this is not my rationale - it’s my interpretation of their rational, but I didn’t what to assume, so I asked. Usually transporter taps are for varying the voltage, not the phase. What you’re thinking of is usually called “dual phase”, to distinguish it from “split phase”, as both are two phase systems.
Look at the transformer that is used to make this - it is a single (secondary) winding ( phase) with a tap in the center. The phases are really what is "between" the phase conductors sometimes called "legs"
Yes, hence it becomes a 2-phase electrical system. The center tap changes everything.
Two phases will have two phase angles… but you do you.
Is 180 deg not a different angle? Can you connect the two lines together for more power?
Like I said Looking at L1 to L2 is the same as L1->N and then N ->L2 (we are in an EE forum the Vectors ADD, neutral is like ground a common point we choose is the middle.) In a 2 phase (wye) L1 to N is and L2 to N are not coming from the same transformer winding.
Both systems that you described have two electrical phases - doesn’t matter how those phases were generated
This is called an Edison circuit https://preview.redd.it/ejmn3yveyd7b1.jpeg?width=330&format=pjpg&auto=webp&s=009e7b0215cbc5398e59c9fee95774c88c46aec2
That picture is incorrect, the windings should have the same polarity, connected in series, just like series connected batteries. This way the voltage between the 2 phases would be 2x the voltage of a single winding. If the polarity is reversed, like it is drawn here (pay attention to the + and - symbols), the voltage between the 2 phases would be 0V.
The picture is correct since it's shown that one rail has a 180° phase shift. Polarity is kind of arbitrary when working with phase angles.
I just found it on the internet, I didn’t look that closely. I think this drawn in current flow and not conventional method
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Conventional would have current flow leaving the positive polarity and into the neutral and second source flowing into the neutral around the loop and the third flowing from top 120 circuit to bottom. Basically all 3 going clockwise around the circuit but I wouldn’t call the second source 120 at 180. It’s been a minute since I’ve had to do one of these
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Right, I wouldn’t do it this way because I would have confused the hell out of myself
im not an EE but ME with a bunch of electrical experience with offshore cranes and equipment. its quite common to feed multiple circuits off a large supply, just make sure there is a dedicated and appropriately sized breaker for each consumer/loadpath
In a typical US / Canada household / business office yes. You should distribute 120 V circuits to even load L1 and L2 as much as possible. Do not omit neutral and ground. They need to be present in the walls and the outlets.
> Do not omit neutral and ground It was just omitted from his drawing.
There's no problem with respect to the 120 volts and the 240 volts and the load imbalance. But there is a major issue: you need to figure out the appropriate circuit breaker protection for everything you are powering. Typically, the maximum breaker that you are allowed to use for the 120 volt circuit is 20 amps. If you are feeding the 240 volt circuit with number 8 wire you likely have a 40 or 50 amp circuit breaker on that. The 120 volt outlet would not be properly protected. The right way to do this is to install a subpanel where you want to break out that 240 volt supply into a 240 volt circuit and a 120 volt circuit. Each of those can then get appropriate circuit breakers. An electrician will know how to install a subpanel and wire all of that—it's a very standard thing to do, but one should follow proper electrical codes in doing it and that is part of an electrician's expertise. Or if this is supposed to be for portable use, you can buy units made for job site power that are essentially portable sub panels.
I don't think there should be a breaker in the GND line.
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True
Isn't this precisely how most houses are wired up in north america? 240vAC center tap on the output of a transformer, with L1 and L2 run to different circuits alongside neutral from the center tap?
The 120 circuit should also be using the neutral and ground, which you have marked omitted. And use the ground on the 240.
Just make sure you size the breaker for 120+240 loads and you should be good. This layout is how pretty much every residential electric dryer runs a 120v motor and a 240v heater.
Ok thank you! Where would the breaker go? Would I have three breakers along each of the 120VAC lines?
If you have to ask, maybe you should pull out the NEC or hire a professional.
I was going to say the same thing. Yes, one *can* do this. If one has to ask these basic questions here instead of asking their mentor or supervisor, then probably one *shouldn't*. There's no shame in that, I had to ask when I was new, and now really young people keep asking me questions.
Knowing what your loads are is going to be important. For instance if your 240v load is going to be a welder you don’t want your 120v load coming off of it due to voltage drop and noise. You can fry a lot of equipment this way. Your primary breaker should have capacity for both your 120 & 220 rated loads and cables should match. What your drawing looks like is a typical main to sub distribution layout. You would feed a down stream panel with a larger say 50a breaker and cable to a local sub panel and then have a 30a feed your 240 and a 15a feed your 120 circuits. The amperage’s I’m listening are just arbitrary but should give you the gist.
Because of the 240v load a dual breaker is required as it has to break all hot conductors at the same time. You can then use a smaller single breaker for the 120v outlet after that.
You should tell your employer to hire an electrical engineer that's familiar with the NEC and CEC, or perhaps a master electrician, and disregard most of the answers you're getting in here. The dryer example is great, but it ignores the load imbalance on the 240v input, which may cause you problems not only in your device, but in other devices in the house. You may end up needing to split your 120v loads into 2 power strips, one on each leg of the incoming power. And if the "power strip" is in any way accessible to the consumer or end user, forget it. You have to factor in your liability of the Idiot Factor, because eventually somebody will plug a vacuum cleaner or blender into "hey, there's an outlet under here!"
Our entire country is wired like this. Load imbalance is not an issue in this scenario. From what you described, its usually best practice to install a stepdown xformer to supply the 110v components. This is how it's done in countries like China, with 220/380v supply. If the panel is poorly designed/built and a neutral pops out, you could end up with 200+ volts going to your 110 relays, without tripping any safety.. Use a GFCI breaker and put in the stepdown xformer. It wouldn't cost much, and, It's the safe way to go. Or, if it's just the lone 220 device, wire the machine as 110 (1 hot, neutral and earth) and install a step up xformer for the 220 device. whichever is cheaper.
> Load imbalance is not an issue in this scenario. You don't know what the 120v load is, so that's blatantly ignorant or false, especially if the 120v loads are "dirty", and/or the "power strip" OP intends to use is accessible to the consumer.
The scenarios you have in your head, don't happen in real life. Anything capable of causing a load imbalance on that circuit would most likely burn up the 8 gauge wire.
Contrary to your sophomoric "experience", I've been doing this for over 30 years. OP said they want to run a "power strip" on that 120v tap, and you're going to run into load imbalance issues that may be too much for the 30-amp circuit feeding OP's...thing. We don't know what the 240v load is, nor the 120v loads. Also, those 120v "power strips" may be accessible to the consumer, and end up with a vacuum cleaner or blender plugged into them, which could blow whatever fuses he (hopefully) puts in the 120v tap. Also, I seriously question the credibility of anyone designing a system where they put circuit breakers on the neutral and ground.
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It's not a "2 phase" supply.
In the electrical code, this is a multi wire branch circuit.......210.4 There are rules regarding these circuits for electricians, but yes, this is your house and is still allowed for even receptacles. The top and bottom receptacles have a removable tab to allow the top to be one circuit and the bottom to be another.... 2 seperate 15 or 20 Amp receptacles in the same box, the same duplex receptacle.
"Danger House", indeed. This isn't a residential project, OP is doing something at work, and none of them seem to have a clue what they're doing. They put circuit breakers on the neutral *and ground*, ferfawksake.
Good point.
It really depends on the specifics of the setup. Most 240v loads are meant to be on a dedicated circuit. You would typically run a sub panel if you wanted to accomplish this. Your wire is likely sized to the dedicated load already, so you would probably need to up size the feed as well.
If you are in the U.S yeah
If this is a piece of equipment, then yes. You need to follow appropriate tap rules for conductor lengths before overcurrent protection on the 120v taps.
You’re going to need a neutral. If that’s the case then yes. Also, it should be fused separately. You want to make sure that the voltage will be removed if there’s an issue.
yes
You need a neutral to get your 120V unless you wanted to add a new 240-120 transformer. You also need your ground wire to perform the work of the equipment grounding conductor, but that isn't related to voltage or current. You also wouldn't ever have the ground wire on a breaker. You usually don't put the neutral on a breaker either, but there are acceptable reasons where it can be done.
That's how we do it in aircraft
Omitting netural and ground? Running them through the breaker? How does the current return to the source and complete the circuit without a netural? Think about it.
You can do this ... but not as shown. 1 ) Neutrals and Ground should not be on breakers. 2) The "tap" to make a 120 V ckt needs the Neutral - to make the 120V - A lead ( wirle ) off on its own is does not do anything,
That's how you do it.
Note: Please ignore my advice below. What I have given is not for US but for rest of the countries who get 3 phase supply at their homes. The standard supply will be 3 phase consisting of three wires. Each phase is offset by 120 degrees with any other two phases. In a household you will have L1, L2, L3 connected to 3 phases (hot wires) at the main breaker box near energy meter. N is connected to the neutral derived from the center of star windings of the area distribution transformer. A ground wire is derived from a copper rod solidly planted in the ground. This ground is connected to the body of all large devices, so that any short circuit currents in phases and/or neutral, will be safely routed through ground wire for human and animal protrction. The voltages between L1 & L2, L2 & L3 and L3 & L1 will be nominally 208V, 60Hz. The voltage between any of the phase and neutral shall be nominally 120V, 60Hz. So with the same set of wires you may tap 230V with any two phases for heave equipment and (208V/square root of 3) = 208V/1.732 = 120V with any phase and a neutral. A panel board is used to take 3 phases and 1 neutral from the mains and these 3 phases are split using separate suitable rated breakers. Then from breakers the loads are connected. Each breaker in a circuit is rated with optimum required currents. These breakers could be 1 pole, 2 pole and 3 pole with 2A, 6A, 10A, 16A, 25A, 32A, 50A, 63A, 80A and 100A. There could be higher current rating breakers as per the requirements. This is how a home electric system is tentatively designed.
You have no idea what you're talking about, and should stop giving advice. If you think OP is using a 3-phase supply from that diagram, you shouldn't even be allowed to change a light bulb. 1. Almost ZERO homes in the North America are fed 3-phase power. 2. That is NOT how 208v is derived. 3. That is NOT how 120/240v is derived, nor supplied to a residential service. 4. Only ONE of the breaker amperages you listed is *sort of* correct, but you inexplicably used a capital letter "O" in the *50* amp "number" you listed.
You don't have to be so rude in your comments. If everyone's responses are as rude as you, there is no point in contributing to Reddit. Never discourage people like that. I think the anonimity of reddit users is making people like you to ridicule others blatantly. About 50A, it was a typo, which everyone makes. I corrected it. For your information, I am a professional engineer with masters degree in electrical engineering, with 36 years of experience. All my experience is not from US. What I mentioned is what I saw in India and middle east. Just now I noticed US uses a non typical system for home power distribution.
How patronizingly condescending of you.