Load capacity of 200-amp panel (2024 Update)

You have a SERIES circuit (considering that the neutral is effectively disconnected).

[snip]
Reply to
Sam E
Loading thread data ...

That makes no sense. 1A counted twice is 1A. No amount of counting changes what exists.

I'm alone in my room. Therefore, counting the number of people in the room shows 1. Now, I look in a mirror and count again. Now there's TWO people in the room.

You have ONE 50-foot rope. Every time you see rope count it. Now you have 10 ropes.

You still haven't shown where that TWO amp current is.

Is it in the first load? There's just 1A there. Is it in the second load? There's just 1A there. Is it in the first supply wire? There's just 1A there. Is it in the second supply wire? There's just 1A there. Is it in the neutral wire? There's ZERO current there. Is it in the air? There's heat there, but no current.

WHERE is it?

[snip]
Reply to
Gary H

You are wrong. It does -- in the case of 120V loads.

IF it's supplying a 240V load, yes. If it's supplying a 120V load, then it exits on the neutral.

So is it your position that a 200A 240V service is incapable of supplying more than 200A at 120V = 24kVA?

At 240V.

How much power can be supplied by a 200A, 240V service? 24kVa, or 48kVA?

No, it's not. It's like saying that *two* resistors IN PARALLEL with 1 amp flowing through each have a total current of two amps. Do you disagree?

No, they are not. Keep thinking about it until you realize why those two examples are not the same, and then you'll understand where you've made your mistake.

Wrong again.

ON EACH CIRCUIT

You've just made current *disappear* into thin air: supplying a single 240V circuit, it's supplying 4800W of power -- but now you claim it's supplying only 2400W when connected to two 120V circuits. Where did that other 2400W go to?

20 amps through each of two circuits = 40 amps.

THANK YOU. Discussion over. That's what I've been trying to tell you for three days now.

20A in each of two parallel legs = 40 amps total. Note that these do have separate returns...

Measured at 120V, yes. But this isn't the same situation, quite, as a residential service. Keep the two ends of that circuit at a potential difference of 120V, and *ground* the point in between the two light bulbs. Then you have 60V flowing through each 60W light bulb = 1 amp *each* = 2 amps

*total* in the parallel circuits.

So you still contend that a 200A 240V service cannot supply more than 24kVA at

120V?
Reply to
Doug Miller

There's no current in the neutral if the loads are balanced.

Reply to
Doug Miller

Wrong. The neutral is "effectively disconnected" *only* if the loads on the two legs are exactly the same. The two legs function as two parallel circuits with respect to 120V loads. Obviously they are indeed in series WRT 240V loads.

Reply to
Doug Miller

1A in _each of two parallel circuits_ is a total of 2A. [...]

The two loads are in parallel, not in series. 1 + 1 = 2.

Two parallel circuits, 1A in each. 1 + 1 = 2.

1 amp in each of the two hot legs -- which with respect to 120V loads, are effectively two separate parallel circuits.
Reply to
Doug Miller

No current. I was replying to the person who claimed 400A.

Reply to
Sam E
[snip]

Of course. The problem is WHERE is the 2A.

No. That would require identical sources. These sources are not identical, but opposite. The difference can be up to 339V (the peak value for 240V RMS).

In the circuit you describe there is ZERO current in the neutral. This is the same as the neutral not being there (current in that wire is 0A in either case). What you have is a SERIES circuit. It is the same current going through both resistors, therefore addition is not appropriate here.

This reminds me of a story I heard a few years ago. Three 12-year-old boys wished they could vote. Since the voting age was 18, the boys decided that if they went together they'd get 2 votes.

12 + 12 + 12 = 18 * 2

The fact that you can do arithmetic doesn't mean it's appropriate to do so.

Reply to
Mark Lloyd
[snip]

Which they are (either in the 200A+200A example or the 1A+1A one).

In a parallel circuit BOTH ends of the loads are connected together (or at least to identical voltages). Neither is true here.

Strangely, I get the idea that you actually know this stuff.

In this 200A service there are THREE current-carrying conductors. Each of these conductors is of the proper size to carry 200A. OK so far?

You say (when this service is fully loaded) that two of these conductors is carrying 200A (for a total of 400A, as you say).

Then where is that 400A going? The only remaining conductor is the neutral, a big enough conductor for 200A (yes, this 400A was at 120V but current is still current and voltage doesn't change the conductor's current capacity).

Somehow I'm imagining a bridge that can handle 200 cars per minute, but that can be 400 if half the cars are blue :-)

Reply to
Sam E

And that almost never happens in real life, either....

Wrong -- both are true.

OK

400A @ 120V, or 200A @ 240V, yes.

Cute. Just answer these questions; assume a 240V 200A service.

What is the maximum power that service can provide?

If all the loads supplied by that service are 120V loads (e.g. blender, toaster, light bulbs, range hood, stereo, TV, computer, etc.) what do you get when you divide that maximum power by 120V?

Reply to
Doug Miller

Assume you are using one leg at 200 amps, that is all the breaker will handle that is 120 volts X 200 amps or 24,000 watts. If you again max out the breaker with 200 amps flowing on both sides that is

240 volts x 200 amps or 48000 watts. Thats the same as 120 X 400 amps. I think the OP wanted to know if he could get a total of 400 amps at 120VAC. Lets rephrase that to could he power 400 individual 1 amp 120 VAC loads from this box under residential conditions. The answer is yes but that sounds a lot like a commercial installation to me where the answer would be NO. I think this is a case of getting the right answers to the wrong question.

Jimmie

Reply to
JIMMIE

Assume you are using one leg at 200 amps, that is all the breaker will handle that is 120 volts X 200 amps or 24,000 watts. If you again max out the breaker with 200 amps flowing on both sides that is

240 volts x 200 amps or 48000 watts. Thats the same as 120 X 400 amps. I think the OP wanted to know if he could get a total of 400 amps at 120VAC. Lets rephrase that to could he power 400 1 amp 120 VAC loads from this box under residential conditions. The answer is yes but that sounds a lot like a commercial installation to me where the answer would be NO. I think this is a case of getting the right answers to the wrong question.
Reply to
JIMMIE

, S=3D

amp=3D

s l=3D

r 400A

Here we go again.....

False. I clearly stated here that it's a balanced load. With a balanced 120V load, the exact same current comes in on one hot and exists on the other. In the case of a 200 amp service, that current is a max of 200 amps.

No and I and everyone else have tried to explain that to you. Go back many posts to the simple circuit diagram I drew:

.

____________ 240V___________ I I I I I I ---------120ohm---------120ohm--------- a b c

You have a 240 volt voltage source as our "service" connected to two

120 ohm resistors in SERIES.

How much current is flowing in that circuit?

1 amp

How much current is flowing in the first resistor?

1 amp

How much current is flowing in the second resistor?

1 amp

What is the voltage across each resistor?

120V

What is the power in each resistor?

120W

So, you have 1 amp flowing in SERIES through each load, so you do have two loads of 1 amp at 120V, but only 1 amp of current is actually flowing in the circuit which comprises the "service"

Capishe?

Now we're back to what Smitty tried to explain to you. Current has nothing to do with voltage. It's based on the amount of charge, ie electrons, passing a point per second. 200 amps is still exactly

200 amps whether it's at a potential of 240V, 120V or a million volts.

And btw, the voltage is not entirely 240V in the above example I gave either. 150amps is flowing at 240V and 50 is flowing at 120V. If it were simply all at 240V, you'd have 48KW of power here. Actually it's 150X240+50*120=3D42KW

That's been asked an answered many times in this thread. It's 48,

Now answer my question. What is the maximum current that is actually flowing in the 3 wire cable of a 200 amp service? If you say it's more than 200 amps, outline an example and using Kirchoff's law, trace for us the current flowing in all 3 conductors.

Absolutely disagree. I gave you an example before. Take a 120W,

120V light bulb and place it between one hot leg and neutral. Take a 120V fan drawing 1 amp and place it between the other hot leg and neutral. You now have a balanced load drawing 1 amp. There is 1 amp flowing in one hot and out the other. The neutral is carrying 0 amps. You are supporting two 1 amp, 120V loads. Total amps flowing in the service: 1 amp. Those two loads appear in SERIES across the two hots.

Several people in this thread say I'm right. No one is saying you are right. So, maybe it's time that you did some more thinking.

two legs

Sigh

Again, you are somehow trying to mix current, which is measured in amps with power and voltage.

Yes, 20 amps through two loads in series. Yes it's supporting two 20 amp loads. But what current is passing through the breaker? 20 amps

No, for 3 days you've been telling everyone here that in the case of a service, you get more amps because there is a second hot conductor. That is flat out wrong. Refer again to the box example later in the thread, where there is no second hot.

Oh no, there you go again. Counting current twice. If that breaker had 20 amps flowing through it at 240V, then it had a 12 ohm load on it. So, now to make it into a 120V circuit, we just remove the 12 ohm load, put two 6 ohm loads in series on it. Now across each

6 ohm resistor you have 120V, with the same 20 amps flowing sequentially through both and suddenly the breaker is now magically carrying 40 amps?

Again, per Smitty and the rest of the world, measuring current has nothing to do with measuring voltage.

It is EXACTLY analogous to a residential service with a balanced 120V load. You have a 120V, 1 amp "service" supplying two 60W, 60volt loads. You have 1 amp flowing in series through the two loads, but ONLY 1 AMP IS FLOWING IN THE SERVICE. If it is not the same as a residential service, tell us exactly what the difference is and why the exact same principles do not apply.

Good grief. If you did provide an alternative "neutral" return path at the point between the bulbs, it would matter not a wit. Just as in the actual residential service, the load is balanced and zero current would flow in the neutral. That is why I left it out as I wanted to keep it as simple as possible. If you like, I can draw you the circuit diagram that represents a center tap 240V service, but it doesn't change how current is counted.

Again, please stop misquoting me. Neither I nor anyone else here ever said any such thing.

Let me restate what I've said all along:

In a 200 amp service entering a house, there is a max of 200 amps of actual current flowing. You don't count current twice on a service cable anymore than you would on an extension cord.

Here's a simple series of questions:

1 I have a big 240V water heater that draws 200 amps and is connected to a 200amp service via the two hot legs.

How much current is flowing in

a - Hot leg 1 b - hot leg 2 c - neutral d - the service cable entering the house

2 Now instead of the single 240V water heater, I have two 120V water heaters that draw 200 amps each. One is connected between hot leg 1 and neutral, the other between hot leg 2 and neutral.

How much current is flowing in:

a - Hot leg 1 b - hot leg 2 c - neutral d - the service cable entering the house

3 Is the situation in #2 above an example of a parallel circuit or a series circuit?

4 I now disconnect the water heater that was connected to leg 2 in the previous example. You now have one 120V, 200 amp water heater connected to leg 1 and neutral.

How much current is flowing in:

a - Hot leg 1 b - hot leg 2 c - neutral d - the service cable entering the house

Reply to
trader4

How can people get this so wrong? It's basic electricity, you all should have learned this in high school.

In a 200A 240V split phase service, any SINGLE 120v load can draw up to

200A, no more. Because it is split phase, you can have two such loads. Now the math. 200A@120V + 200A@120V = 200A@240V, NOT 400A@120V. Because two 200A 120V loads on a single split phase panel are in fact operating in series (whether you deliberately wired them that way or not), presenting a de facto 200A 240V load on the panel. And, yes, in that case the neutral conductor current is zero.
Reply to
usenet-659f31de7f953aeb

But a balanced load is exactly what was shown in the simple circuit example above that he understood and is discussing.

Which matters not a wit. Unless of course you are trying to get close to the maximum capacity of the service. If it's totally unbalanced, guess what? You get 200 amps at 120V, or exactly half the power capacity of the service. Gee, I wonder why? Could it be that it's because the service can only handle 200AMPS? And that with a 200 amp unbalanced load at 120V, 200 amps is coming in on one hot and it's all going back on the neutral?

Wow, it's getting really strange here. Of course, by definition, a parallel circuit is one where the ends of the individual elements are connected together. A series circuit is one where elements are connected one after the other, in series.

And there you go again, inserting voltage into a question of amperage. Amperage is a measure of the charge, ie electrons passing through the conductor and IS NOT LINKED TO VOLTAGE.

You;ve asked that question multiple times and it's always been answered the same: 48KVA

Now answer his question that you avoided. Apply Kirchoff's law and tell us where current is flowing in a 200 amp service cable that totals up to 400 amps. All of us here agree and can account for

200amps. So explaing the missing 200.

If it's a balanced load, you get 400 amps because half the load is in SERIES with the other half. As I've outlined about 6 times now, you have 200 amps coming in on one hot, going through the loads in series and then out the other hot. 200 amps is flowing in the service. If you say it's 400, then why isn't it 2 amps that flows in a 120watt light bulb plugged into an outlet? 1 amp comes in one wire, 1 amp goes out the other wire. Yet the world agrees that only 1 amp is flowing, not 2.

If it's a totally unbalanced 120V load, then you can't just divide the power by 120 as youu imply, because you have 200 amps flowing in on one hot, and 200 amps flowing out on the neutral. So you have a

120V, 200 amp load and only a power of 24KVA.

No matter how you slice and dice it, there is a max of 200 amps flowing in the service. Since you believe otherwise, outline the current flows as I have here and how it adds up to greater than 200 amps flowing in the service conductors.

Reply to
trader4

This is the only error I picked up. The supply voltage, as stated, is

120V in both cases. In the second case the 2 60W bulbs would have to be in parallel to give a load of 120W and 1A. Assuming the light bulbs are linear resistances, with 60V across a 120V bulb you would get 1/2 the rated current, or 1/4A which gives an effective wattage in the 2nd case of 30W.

That isn't what you intended.

The arguments have gotten so twisted let me start here.

Everyone, I believe, has the same the answers (though I'm not sure what "d" is).

The question from the OP, as I understand it, is with a panel feed at

200A 240V can you supply 200A of 120V load or 400A of 120V load.

It is case #2 above. You can supply 400A of 120V load. You can't supply a 400A 120V load, but with the load split between the legs you can supply a total of 400A of 120V load, half of it from each leg. In that case the hot legs run at 200A and the neutral is zero. You don't have

400A on any wire. I assume that is not a problem for you. That is all I read Doug as saying. I agree.

Its gotta be a point-of-view problem.

Reply to
bud--

Yes, I agree. good catch.

120W bulb -> 120 ohms 60 W bulb -> 240 ohms 240W bulb -> 60 ohms

So, in my example I should have used two 240 watt bulbs in series which would be the same resistance as the 120watt bulb. Actuallly, I should have used a simple resistor or similar, because the resistance of light bulbs is not a constant, temp dependent, etc.

But the example, corrected, still holds. You would have 60 volts and

1 amp flowing across each bulb.

I'm not so sure there is agreement as to the answers. And if there is agreement, then I don't see how there can be disagreement on how many amps are flowing on the service cable. If you have X amps coming in and X amps going out in a circuit, then that means X amps, no?

I don;t see it as a point of view problem at all. How many amps are actually flowing in a 200 amp service to a house? You draw an imaginary plane and answer the question of how many amps are flowing in and how many are flowing out. If it is indeed 200 in, 200 out, then that is 200 amps period. You can have 200 amps flowing between the two hots. You can have 200 amps flowing between hot 1 and the neutral. You can have 200 amps flowing between hot 2 hot and the neutral, Any way you slice and dice it, it's still 200 amps.

If you can really have 400 amps of real current flow in the service, then maybe Doug can answer this. Suppose I have a 120 volt load that takes 400 amps. I connect it as a single 120V load to a 200 amp service. What happens?

A - Eveything works peechy keen, because 120V* 400amps =3D 48KVA, at the service limit, so 400 amps flows just fine.

B - The service cable burns up, because the only way you can supply that 400amps is by the load being balanced, in which case it appears as a series load and the service is actually pulling 200amps through one hot and back the other. Which means that it would ONLY work if you had two 200 amp, 120V loads connected to OPPOSIITE legs, and hence acting as a SERIES circuit.

Reply to
trader4

QUESTION...

In a service rated as a "200 Amp service"..

What are the numbers printed on the TWO main breakers?

Are they

A) 200/200?

or

B)100/100?

That is really the only question that needs to be answered .....

The rest should be obvious.

Mark

Reply to
Mark

that supply at

in other words, is this:

formatting link
considered to be a "100 amp service" or a "200 amp service?

Mark

Reply to
Mark

I don't understand Doug is saying there is 400A running in any wire. And I am not saying there is.

In example #2 there is there 200A supplied to the 120V water heater on leg 1. And there is 200A supplied to the 120V water heater on leg 2. Are you not supplying 400A of 120V load (split between leg 1 and leg 2)?

I do not understand Doug ever said there was 400A in any wire. Rather that there was 400A of total 120V load supplied - 1/2 on each leg.

You don't connect it to one leg. You split the load in half and connect one half leg 1 to neutral. You connect the other half from leg 2 to neutral. (In this case you reconnect the single 400A 120V load as a 200A

240V load.)

If you have 40 - 10A 120V loads (400A total at 120V) you connect 20 of them to leg 1 (200A). You connect the other 20 to leg 2 (200A). The neutral current is zero. You have supplied 400A of 120V loads by splitting it and connecting half to each leg.

Which is how you connect it. I don't want to go back and reread the thread - Doug's use of parallel may have not been the best. But I always understood he was saying that half of a 400A load (200A) was connected to leg 1 and the other half (200A) was connected to leg 2.

In answer to the OP's question - with a panel feed at 200A 240V can you supply 400A of 120V load - the answer is yes.

I still think it is a point-of-view problem. You and Doug (and Smitty and others?) all understand the underlying electrical.

Reply to
bud--

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.