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[TyPope]

I suppose

Like this?

 

[TyPope]

Like

But then how do you break up a post into multiple quotes? this?

 

[ajdelange]

Here's what my last post looked like in the editing window

[QUOdE="Bill906, post: 12790, member: 2826"]
1. You can only get 200A from a 200A system. ...[/QUOdE]Yes, but that's 200 A per phase. If I have a generator that delivers 1 kW for 2 hours that's 2 kW-hours of energy. ...
[QUOdE="Bill906, post: 12790, member: 2826"]2. Although someone could argue a center tapped winding creates two phases 180° apart, I believe ... [/QUOdE]Note that I didn't argue that. I just said my panel's capacity is 400 phase amps. But as you have brought this up I...

[QUOdE="Bill906, post: 12790, member: 2826"]
The two main benefits of multi-phase power is A) Allows...[/QUOdE]"

Note that I never said anything about polyphase systems ...

[QUOdE="Bill906, post: 12790, member: 2826"]
This is my first time quoting someone. I hope I did it right.
[/QUOdE]
Yes, you did and thanks for taking the...

 

[TyPope]

Here's what my last post looked like in the editing window

[QUOdE="Bill906, post: 12790, member: 2826"]
1. You can only get 200A from a 200A system. ...[/QUOdE]Yes, but that's 200 A per phase. If I have a generator that delivers 1 kW for 2 hours that's 2 kW-hours of energy. ...
[QUOdE="Bill906, post: 12790, member: 2826"]2. Although someone could argue a center tapped winding creates two phases 180° apart, I believe ... [/QUOdE]Note that I didn't argue that. I just said my panel's capacity is 400 phase amps. But as you have brought this up I...

[QUOdE="Bill906, post: 12790, member: 2826"]
The two main benefits of multi-phase power is A) Allows...[/QUOdE]"

Do you have to manually break it up like that?

 

[ajdelange]

Yes but it's all cut and paste and so not difficult to do.

 

[Bill906]

A typical residential service in the US has a single phase transformer where the secondary winding has a center tap. Hot 1, Hot 2 and Neutral. (H1, H2 and N). You will measure 240VAC between H1 and H2. 120VAC between H1 and N and 120VAC between H2 and N. In a 200A service H1 has a 200A fuse (or more likely circuit breaker) in it. H2 has a 200A fuse or CB in it, N is not fused. If I put a 0.6Ω resistor between H2 and N I will have a 120VAC voltage drop across the resistor. I will have 200A flowing through H1, the resistor and neutral. (this is assuming no load on H2). This would be the same on the other side if I had a 0.6Ω between H2 and Neutral.

If I put a 0.6Ω resistor (R1) between H1 and N, and put another 0.6Ω resistor (R2) between N and H2. You would have 200A flowing through H1 R1 R2 H2. If the center tap was perfectly centered, and R1 was exactly the same resistance as R2 you would have zero current in the neutral center tapped connection. Any imperfections would cause an imbalance and cause current to flow in the neutral.

If I lower either of the resistances (which increases load) I would draw more than 200A through either of the fuses and they would eventually trip.

Please explain where the other 200A comes from.

 

[ajdelange]

I did. 200 A flows in one phase. 200 A in the other. There are 400 Ampere phases.

Call it a 200 amp single phase 240V system if you want. That's 200 amps per phase (200 øA) and 240 V/ø product 48 kVA, Call it a split phase system with two 200A phases at 120 V per phase. Thats 400 øA at 120 V/ø each for a product of, voila, 48 kVa. Let it be a Y connected panel in a 3 ø system with each phase capable of 200A and at voltage 120V. I have 400 øA times 120V/ø for a total of, again, 48 kVA but note that this time I have to take them at 120V. IOW I can connect separate 24 kVa loads across each of the phases but I can't put a single load of greater than 41.6 kVA between the two phases without drawing more than 20 A. Thus one has to be a little more careful with the phase ampere rule in a 3 ø system.

 

[Bill906]

It's the same 200A flowing through both resistors. They are in series.

Are you saying 200A comes in on H1. 200A comes in on H2 and 400A goes out N?

This why I don't like calling them two phases. There is one 200A phase cut in half. Split-phase.

 

[TyPope]

Stay on target. Stay on target. (I'm guilty of hijacking some threads)

I went ahead and just now ordered the Gen 3 charger. I probably could have managed to get an off brand thing and had the local utility pick up the tab but I figured... in for a penny, in for a pound.

Anyway, when I got an email from Tesla that had the subject line of "Your Model Y—Delivery Update ", it kind of made me realize that once they set up a delivery date, I'm going to run out of time quickly to get a charging solution set up. So, step one is done. Now, back to waiting.

 

[ajdelange]

It's the same 200A flowing through both resistors. They are in series.

No, not necessarily. There could be 200 amp on one phase and 150 on the other. At 120 V/ø that's a total load of 200 øA + 150 øA = 350 øA At 120 V/ø that's 42 kVa. The fact that the panel has 200 øA capacity per phase for a total of 400 øA does not mean that the same current has to flow in the two phases. Quite the contrary. That's why there are two phases.

If you can't follow the above and therefore understand the utility of expressing loads and services in terms of phase amperes then I think you are just going to have to accept that it is not given to all men to understand all things and realize that this concept isn't in your scope. That does not mean others cannot use and benefit from it.

 

[ajdelange]

Separate post here because while the previous couple were probably of no interest to most there is a message for anyone considering installing HPWC when it comes to looking at adequacy of his service. Go look at your panel. At the top there will be a large breaker most probably with two poles (toggles) but possibly 4. Look at the number(s) on the breaker. Multiply that by the number of toggles. Typically you might have a breaker labeled 200 with 2 toggles. The product is 2*200 = 400 pole amperes and that is your service capacity in pole amperes. In one of my panels the breakers are labeled 100 and there are 4 of them (4 toggles). The service is 400 pole amperes in this case too. There may be a single breaker with a single handle with a single number on it. This is also a 2 pole 200 A breaker and so the service size is still 2 *200 = 400 pole amperes in this case. Now whatever the number of actual poles the service in all these cases is 200 A per phase and is described as "200 amp split phase" in most cases.

Now go through the branch circuit breakers doing the same thing. For single phase breakers just add the amperes up. For duplex breakers double the rating i.e. for a 15 A duplex add 30 pole amperes to the total. As is the case with the service breakers dual pole breakers may consist of two single pole breakers with the toggles tied together or a single unit with a single handle and a single label so you need to be careful with those. It's obvious that two 20 A breakers mechanically tied together constitute a 40 pole ampere load. It may not be so obvious that a fat breaker with a single handle labeled 20 A is also a 40 pole ampere load.

In any case if the total of the branch circuits plus the load of the HPWC you intend to add is less than twice the service pole amperes you should be fine. Example: a Gen 3 HWC set for 48 A charging is a 120 pole Ampere load. Set for 40 A charging it is a 100 pole Ampere load and so on. If the HPWC pushes the total load to over twice the service number you may still be OK but that is up to the inspector to decide. This is another reason why you should consult a local electrician on all this.

 

[Aces-Truck]

A.J. has it basically right.

For some additional clarity:
When you put 120V Breakers in, first CB use H1 (to bridge to neutral), the 2nd uses H2, 3rd uses H1, etc. But if you want 240V, Your CB uses two adjoining spots, to bridge between H1 & H2. So if all you ever needed was 120V, you could have 400A of breakers in a 200A service. But we often need 240V, for Range, water heater, dryer, and to feed sub-panels. So if you have a 200A service, and put in a 100A subpannel, it's going to be able to 100 A off of each side, H1 & H2. So now you are left with 100A in your main, for each of H1 & H2. So if yo had two 30A breakers in, along with your 100A for the sub-pannel, you could have a total of 140A of 120V CB's in the pannel. Now having said this, chances are, you won't have every CB pulling current at capacity at the same time. So you may be able to push that somewhat. If you do, it's important to look at what loads are on each side. Ideally you want the same amount of draw on both H1 as on H2 in those high draw situations.

Here's a link for some more explaination: "https://www.doityourself.com/forum/...p-single-phase-service-per-line-combined.html"

 

[Bill906]

You cannot get 400A from a 200A single phase typical residential service.

Since explaining using basic electric circuit theory isn't working let me try a different approach.
The point of this tread is discussing home charging systems.
AJ implied that if you have a 200A service you really have 400A and you should use 400A when deciding what you can handle.
For simplicity sake, lets say I have a typical 200A service going to my detached garage. Let's say I want to have multiple 50A BEV chargers in that garage. If I have no other loads in that garage, and I want to use them all at full load at the same time, how many can I have? 4 or 8? (4 chargers would be 4 * 50A = 200A load. 8 chargers would be 8 * 50A = 400A load.)
The answer is 4.

I understand there are codes and rules to follow etc. But I needed to simplify it so everyone could understand.

Back to basic circuit theory... I think what you are doing is measuring the current though each load and then adding them. That is not how it works. The loads on H1 to N are in series with the loads on H2-N. If you had a 240V supply and 24 resistors 10Ω each all in series you would measure 1 amp thru each resistor. That does not mean your supply is supplying 24A. It's supplying 1 A through the entire resistor network.

Others do not benefit when you give them wrong information.

Others many not have interest now, but they will if they've overestimated their 200A service when installing their charger/chargers.

 

[ajdelange]

You cannot get 400A from a 200A single phase typical residential service.

Well of course you can. I once took 1001 amperes out of a 200 A residential service. I just didn't continue very long. But back to the topic at hand. No one ever said that you could take 400 amperes out of a 200 amp residential service, But a 200 amp residential service provides two 120 V phases (whether you like to call them that or not) at 200 amps each. It is thus a 400 phase-amp service.

AJ implied that if you have a 200A service you really have 400A and you should use 400A when deciding what you can handle.

AJ never said nor implied that. In fact he specifically pointed out that this was not the case as did one other poster.

For simplicity sake, lets say I have a typical 200A service going to my detached garage. Let's say I want to have multiple 50A BEV chargers in that garage. If I have no other loads in that garage, and I want to use them all at full load at the same time, how many can I have? 4 or 8? (4 chargers would be 4 * 50A = 200A load. 8 chargers would be 8 * 50A = 400A load.)

The chargers are two phase devices drawing 50 A per phase. Often they are connected across two phases of a 3ø system though that is not common in a residence. Nevertheless they are connected across 2 phases in a residential system too. It's just the phases are 180 ° apart rather than 120°. Nevertheless, a 50 A EVSE requires 2*50 = 100 øA. 8 chargers would require 800 øA. As the service is 400 phase amperes and the chargers are 100 øA each you can connect 400/100 = 4. You have some sort of mental block in understanding this so just give up and let the rest of us who do sail on. You don't need to be able to understand it for the rest of us to use it. The rest of us get the same answer you do even if you can't understand how.,

I understand there are codes and rules to follow etc. But I needed to simplify it so everyone could understand.

Believe me, you aren't simplifying anything. You are just muddying the water for others.

Back to basic circuit theory... I think what you are doing is measuring the current though each load and then adding them. That is not how it works. The loads on H1 to N are in series with the loads on H2-N.

No indeed. I think you need to review basic circuit theory. The loads on phase A are NOT in series with the loads on phase B as I and at least one other poster have repeatedly pointed out to you. They are on separate phases of a two phase system. The currents is series connected loads are the same. Exactly. All the current that flows through one flows through another. If I have a 20 amp load on phase A and a 10 amp load on phase B the currents are different so it is clear to someone who understands electricity that those loads are NOT in series. Twenty amps is flowing into phase A but only 10 is coming out phase B. Where are the other 10 A flowing into load A going? Back to the panel via the neutral of course. A 20 A load at 120 V implies 120/20 = 6 Ω resistance. The 10 A load is twice this at 12 Ω. If I took the neutral away what would happen? Then the loads would indeed be in series and the current in each would be the same at 240/(6 + 12) = 13.33 and there would be 80 V across the 6 Ω leg and 160 V across the 12 Ω load.

Others do not benefit when you give them wrong information.

True, so PLEASE stop giving them wrong information!

Others many not have interest now, but they will if they've overestimated their 200A service when installing their charger/chargers.

It seems everyone but you understands this concept. When you find yourself alone in your thinking it is often a good sign that you should review your thinking. I think perhaps you are not too familiar with polyphase systems. I also think that if you go back to the earlier posts in this formum and some of the material the other poster linked to with a mindset that says "Hey, maybe these guys know what they are talking about" rather than one that says "Hey, whatever these guys say I know they are wrong so I'm going to ignore what they say" you could probably understand this as it isn't rocket science. Hundreds of thousands of engineers and electricians use it every day,

 

[cybrtrk_maybe]

I don't have a breaker at the top, I have one at the bottom. It is a 200 A breaker; Does this mean I have 400 A available?