Load capacity of 200-amp panel

Page 5 of 9  


The correct answer is actually 400 amps of 120volt load IF THE LOAD IS PERFECTLY BALANCED. IF it's anything less than perfectly balanced, you can not support 400amps of load. If it's totally unbalanced, you only get 200 amps.. Partially ballanced, you get between 200 and 400. The only way you can get 400 is if it is perfectly balanced so that the 120volt loads are in SERIES and appear as a 200 amp 240volt load.
Agree?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 28, 3:59 pm, snipped-for-privacy@optonline.net wrote:

No, if the load is balanced there is no 120 volt loads just 240s. 240 X 20 also equal 48KW.
If what you were saying is true you could hang your ammeter on the neutral line and measure 400 amps.
It doesnt just appear to be a 240 volt 200 amp load IT IS. The two loads are in series, same electrons going through both of them. Its not fair to count electrons twice.
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm not counting electrons twice. Neither is Bud. I take 200 amps worth of 120Volt eqpt and plug it into outlets that are driven off of one hot leg of the 240Volt 200 amp service. I take 200 amps worth of 120volt eqpt and plug it into outlets that are driven off the second hot leg. I am now supporting 400 amps of 120volt loads. It doesn't get any more basic than that. I agree the current is flowing in series and is actually a 240Volt total load and the service is running 200 amps. That is what I have been saying all along when others were saying that you have conductors in parallel, a second conductor carrying more current, etc. But from any reasonable perspective, if I can plug 400 amps worth of 120volt eqpt into the house, then I am in fact driving those loads.
If the homeowner asked you how many amps worth of 120Volt eqpt is the max that the 200 amp service can support, what would your answer be?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 28, 5:43 pm, snipped-for-privacy@optonline.net wrote:

By the way, are you the same Jimmie that posted this a while back?
"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 "
So, now how come when I say the max 120v load that a 200 amp service can supply is 400 amps and then if and only if the load is perfectly balanced, you say NO?
If the homeowner asked you how many amps worth of 120Volt eqpt is the max that the 200 amp service can support, what would your answer be?-
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
This thread will go for ever with no satisfying conclusion because of the talk about AMPS instead of Volt Amps or Watts.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You can have 1000 watts with 1 volt and 1000 amps or you can have 1000 watts at 1000 volts and 1 amp. If you follow your logic the power distrubution boxes would be the same.
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Panel capacity isn't measured in VA or watts. If the connections in a panel have enough resistance to cause significant power dissipation then you will very very quickly have burned out connections.
A panel can easily carry enough current for a 10KW load, but if there is so much as 0.05KW of power dissipation inside a connection in the panel, you'll quickly have a burned out connection.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Where have you ever seen a panel rated in VA or WATTS?
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 28, 5:43 pm, snipped-for-privacy@optonline.net wrote:

200 AMPS, 200 amps x 240 volts also equals 48000 watts. I suggest you post this to one of the engineering groups. This is a classic question that has been in electical course for years. Ive been thru three such courses in the last 22 years and havent missed the question yet. One course was for power distribution, one was for HVAC and the other was for power generation.
And yes you are counting electrons twice. And your perspective is wrong because the loads are not across 120, there return path is not through the neutral. You have 2 120vac loads connected in series across 240 vac.
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Wrong.
And I have a degree in electrical engineering from MIT and I say you are nuts. The homeowner brings home twenty 20 amp 120 volt heaters. He connects half of them to outlets on one side of the service. He connects half of them to outlets on the other side of the service. He now is unquestionably supporting 400 amps of 120volt load. It doesnt' get any simpler than that. In fact, I think everyone in the entire thread except you would agree with the above. Sure it is because it works as a series circuit and appears at the service point as a 240volt, 200 amp load. Everyone knows that. But as far as the loads go, you do have 400 amps going through them, 120V * 400a = 48KVA of power
Accoridng to your answer above, what would the homeowner do? If he listened to your answer, the homeowner could only buy and connect ten of those 20 amp heaters, because he can only support 200 amps at 120volts.
And aren't you the same Jimmie that posted this back in the beginning of the thread?
"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 "
Yet, now you say it aint' so.

The homeowner can bring home 400 amps worth of 120volt eqpt and plug it in and it works. Any place in the universe, that means the service is supporting 400 amps of 120volt load.
In fact, that is exactly what you said in your own post, which I showed above.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:

What a coincidence. I have a degree in electrical engineering from the (university of) Minnesota Institute of Technology too.

What a coincidence. I think he is nuts too.

Hey - that's not fair.

Why would you use such an underhanded tactic to ruin a perfectly good argument?
-- bud--
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:
[major snippage]

ROTFLMAO! This is *exactly* what I've been saying in this thread for the last week -- and you've been telling me I was wrong.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:

Yup.
Have fun with JIMMIE. Surprising how a simple question is so controversial.
I don't see the series argument as particularly interesting, but maybe again POV. In a slight tangent, if you have a 200A 3-phase 120/208V Y panel and load A-phase at 200A 120V, B-phase at 200A 120V, and C-phase at zero, you will have 400A connected 120V load and a 200A neutral current.
The same is true with a single phase panel fed by 2 legs of a 3-phase supply. I believe you can get that in large apartment complexes that have a 3-phase service.
And I hesitate to say it again, but I understood Doug to have said the same thing as in the previous 2 posts. I think he used "parallel" once, which I understood to mean "combined" (200+200), as applied to the 120V loads. I don't remember he ever other wise implied there was 400A in the neutral.
--
bud--

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, it sure is. Even more so when Jimmie is on both sides, essentially arguing against his own post.

The only issue I have with Doug is that he refuses to acknowledge that there is only a max 200 amp current flowing in the service cable. I freely answered ALL his questions, yet for some reason he won't give a straight answer to the simple question of how many amps max can ever be flowing in the service cable. And in trying to evade the question he dragged in voltage and power, which are seperate from the question of how many amps max are ever flowing in the service cable.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:

"But as far as the loads go, you do have 400 amps going through them, 120V * 400a = 48KVA of power".
That's a quote from one of *your* posts.
Apparently, it *is* possible to have a current > 200 amps -- as long as it's you saying so, not me.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 29, 8:24 pm, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Nope I made a mistake, I meant to point out that the OP could get the power he wanted but not at 400 amps. What I said was wrong. Im still trying to figure out what led me so say what I did . There are lot of numbers you can multiply times each other and get 48K you might as well pick any from the group if you use your logic. The panel is rated 200 amps @ 240 volts, not 400 amps@ 120 volts. Power has nothing to do with it. I could use the box to distribute 24VAC and it would still only be able to handle 200 amps. According to your logic it should handle 2000 amps, Hey that's 48KW said very much tongue in cheek..
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So expalin us the physics whereby I can get 48KVA at 120 volts without a current of 400 amps.

No, when you said a 200 amp service can support 400 amps worth of 120volt load you were correct. It's now that you;'ve reversed yourself that you are wrong.

That is correct because that is EXACTLY what you can do. Which is why I gave other examples. Let's take a heater consisting of a a . 3ohm resistance. The box says it's 60volts, 200 amps, 12Kwatts or KVA. Agree?
I take TWO of those and place them is series and connect them to one side of the service. I take another two and place them in series on the other side of the service. I now have 4 loads. Each one is running at 200 amps and 60volts. Agree?
I'm now supporting FOUR 200 amp, 60 volt loads. Across the service it looks like one 240volt, 200 amp load. Capishe?

No, according to my correct logic and math the current in the service is still 200 amps which is what the panel is rated for. However if I use voltage division, I can divide up that VOLTAGE across various loads any way I want. I gave you a clear example of that above.
Since you say otherwise, please to explain how a 240volt, 200 amp 48KVA service becomes only capable of supporting 200 amps of 120volt load. You even said if the homeowner asked you:
What is the maximum 120 volt load that I can hook up to this 200 amp, 240volt servce?
Your answer would be 200 amps.
My answer and I think virtually everyone else in this thread's answer is 400 amps, because in fact that is how much 120 volt load can be hooked up. With your answer, the homeowner goes out, looks at the rating labels on all the equipment and is limited to 200 amps, 120volt, 24KVA. Where is the rest of the poor guy's power?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 31, 10:37 am, snipped-for-privacy@optonline.net wrote:

But the box doesnt see them as 120 volt loads. It doesnt care.
Case 1 : if they are all connected to one leg of the 200 amp service all you can draw is 200 amps before the breaker pops with 0 current in the other leg. Yo uare only using 1/2 the box.24KW Case 2 Same as case 1 but for the other leg. Case 3 they are evenly distributed on each leg, when you do this the box no longer sees them as individual 120vac loads but sees them as 240vac load so now you have 240vac at 200amps or 48KW
AT no time were you allowed to excede 200 amps.
In case 1 the current path is 200 amps from L1 to the neutral wire. In case 2 the current path is from L2 to the neutral wire. In case 3 the current path is from L1 to L2. L1 and L2 ar across 240 vac not 120vac. In this case the 120 vac loads are in series forming 240 vac loads. 240vac x 200amps = your 48Kw There are no 120VAC loads as far as the panel is concerned.
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No shit Sherlock. I never said anything inconsistent with that.

The operative word here is LOADS. It's plural because there are TWO 120volt loads, with a current of 200 amps flowing through EACH of them. If instead of TWO 120volt loads with 200 amps flowing through each of them, you can have only one 120volt 200 amp load, which is what you claim, then you just lost half your load capacity and the math does not add up.
You told the homeowner the service will only suipport 200 amps of 120volt load. Following your answer, he buys only 200 amps worth of 120volt eqpt and that is all he ever hooks up, drawing a max of 24KVA. You're comfortable with that answer?
Following the answer the rest of the folks in this thread know to be correct, he goes out and buys 400amps worth of 120volt eqpt, places half of it on one leg, half on the other, and he's got 48KVA. Our math adds up, yours does not. It's also not even debatable, because we all know in the real world that 200 amp service can in fact support 400 amps of 120 volt eqpt. Not a single person in this thread is arguing otherwise, except you.

And one more time, I have said the total current flowing in the service cable is a max of 200 amps.

Who cares as far as the panel is concerned? That is not the issue. The issue is how much current is flowing as far as each of the 120volt loads is concerned. The panel with 200 amps flowing can support a VARIETY OF VOLTAGE and loads. You can divide up the voltage across multiple loads any way you want. I gave you an example of how you could divide it up and get that 200 amps flowing across four 60 volt loads. You then are supporting 800 amps worth of 60 volt load. 800X60=48KVA and once again, we have all the power accounted for across all four loads.
Again, the simple question from the homeowner is:
What is the maximum 120volt load that I can support in my house with a 200 amp service. The answer is always the same, 400 amps. You still have not explained how the homeowner gets cheated out of half his power if he listens to your answer and only buys 200 amps worth of eqpt. Doesn't that bother you?
One more time:
------------------- 240Volts-------------- I I I I I I I---------.6ohms--------.6ohms-------- load 1 load 2
Simple, basic questions:
How much current is flowing in this circuit: 200 amps
What is the current flowing in load 1: 200 amps
What is the current flowing in load 2: 200 amps
What is the voltage across load 1: 120volts
What is the voltage across load 2: 120volts
What is the power in EACH of these loads? 120voltsX200 amps= 24KVA
How many amps of 120volt load is being supported? 400
How many amps worth of 120 volt heaters could I buy and hook up in this way? 400
What is the total power? 120voltsX400 amps=48KVA, or 240voltsX200 amps =48KVA.
Notice how the math ALL adds up. There is no missing power and the homeowner gets to hook up 400 amps worth of 120 volt eqpt. hust like in the real world. Following your answer the poor guy only hooks up 200 amps worth of 120volt eqpt. Where did the other half of his power and load disappear to?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Nov 1, 8:41 am, snipped-for-privacy@optonline.net wrote:

Then clarify one thing , are you saying that there is 400 amps flowing in the box somewhere.
Jimmie
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It 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.