400 amp service w/(2) 200 amp main breakers

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jefftaman

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Table 310.15(b)(6) requires 400kcmil for a 400 amp residential service. If the there is not a 400 amp main breaker but rather (2) 200 amp main breakers, handle tied together, is 2/0 allowed for the service entrance conductors?
 
Jeff,

What kind of panel are you using that has 2-200 amp CB's tied together. Is this in effect a 400 amp panel with a 400 amp main?
 
I have not seen the panel, I do know it is a Cutler/Hammer 400 amp service. The issue is our local POCO has 2/0 for the service drop and they said they cannot connect to the 400 kcmil. The homeowner's electrician is arguing that since there is not a 400 amp main but rather (2) 200amp mains tied together the service entrance conductors only need to be 2/0, since the SEC's will go to a 200 amp breaker not a single 400 amp main. I hope this makes sense.
 
I looked through the Cutler Hammer catalog and couldn't find what you are describing.
Not having seen the loadcenter, it would seem that unless there are two sets of bussing (each fed by one of the breakers), it must be a 200 amp panel.
Something here makes no sense whatsoever.
I would like to see this if you get a catalog number.
 
jefftaman said:
I have not seen the panel, I do know it is a Cutler/Hammer 400 amp service. The issue is our local POCO has 2/0 for the service drop and they said they cannot connect to the 400 kcmil. The homeowner's electrician is arguing that since there is not a 400 amp main but rather (2) 200amp mains tied together the service entrance conductors only need to be 2/0, since the SEC's will go to a 200 amp breaker not a single 400 amp main. I hope this makes sense.
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I install alot of 320 amp meters that contain two, 200 amp breakers, I usually just run 4/0 AL to the panels inside the house...
 
jefftaman said:
The issue is our local POCO has 2/0 for the service drop and they said they cannot connect to the 400 kcmil.
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They can and they will. Ask to speak to someone else.
 
Per the original post, can you think of any reason why you would have a handle tie on these two breakers?
Have you ever seen this done on that particular setup?
 
My own homes 200 amp service panel is a GE and it basically has two 100 amp breakers wired in parallel under a single handle tie. Identical overcurrent devices wired in parallel will provide twice the current carrying ability of one.

Is it possible CH has two 200 amp breakers arranged in parallel to supply a 400 amp panel. (Side note, we can not wire overcurrent devices in parallel 240.8, but the manufacturers can and do)

That aside a couple questions should be asked.

1) What is the panel boards current rating listed as on the label?

2) What is the calculated load that this is supplying?
 
I'm trying to follow this thread and I'm confused about a few things :
1) Is this a 400 amp overhead service in a residential area ? Haven't seen too many of those.
2) If so, most of the POCO's that I deal with carry insulated barrel crimps on their truck that are suitable for up to 2/0 copper. They can't crimp onto 4/0.
3) If you've calculated for a 400 amp service then shouldn't the feeders for the "total" service have to be sized for 400 amps ?
4) If you've calculated for a 400 amp service how can you use a disconnect that is rated at 320 amps ?

Any 400 amp (or greater) services that I've done have been fed underground into a CT cabinet with a special POCO wired meter socket. Once you leave the CT cabinet and wire into 200 amp main disconnects you can use 2/0.

If I'm looking at this in a wierd way or not thinking "out of the box" would someone please say so and point me in the right direction ?
 
This is a residential 400 amp overhead service, this guy has a christmas light display beyond belief. I have not seen the panel but I will call the guy on Monday to go take a look. He is stating one 200 amp breaker feeds one bus and the other 200 amp breaker feeds the other bus, the breakers are tied together. So theoreticaly each ungrounded SEC will never be subjected to more than 200 amps, which is why he arguing that he only needs 2/0. If this had a 400 amp main then it is a no brainer, but the two 200 amp mains is throwing me for a loop.
 
jefftaman said:
This is a residential 400 amp overhead service, this guy has a christmas light display beyond belief. I have not seen the panel but I will call the guy on Monday to go take a look. He is stating one 200 amp breaker feeds one bus and the other 200 amp breaker feeds the other bus, the breakers are tied together. So theoreticaly each ungrounded SEC will never be subjected to more than 200 amps, which is why he arguing that he only needs 2/0. If this had a 400 amp main then it is a no brainer, but the two 200 amp mains is throwing me for a loop.
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What about the grounded conductor potential
 
Follow the money ....... somebody doesnt want to pay for new upsized SEC's
the utility wont provide 400a service ? are u kidding me? The contractor porbably doesnt have wiggle room to upsize his end of the deal.....
unfortunately been there done that.....
but beyond that what happens when the homeowner loads up and starts kicking the 200 amp CBs that are supposed to give em 400 ?
just a few thoughts
 
jefftaman said:
This is a residential 400 amp overhead service, this guy has a christmas light display beyond belief. I have not seen the panel but I will call the guy on Monday to go take a look. He is stating one 200 amp breaker feeds one bus and the other 200 amp breaker feeds the other bus, the breakers are tied together. So theoreticaly each ungrounded SEC will never be subjected to more than 200 amps, which is why he arguing that he only needs 2/0. If this had a 400 amp main then it is a no brainer, but the two 200 amp mains is throwing me for a loop.
Click to expand...
Still sounds like a 200amp service...Are they single pole 200's (have never seen one)? Since the each only feed one buss? Something just doesn't sound right here.....
 
goldstar said:
I'm trying to follow this thread and I'm confused about a few things :
1) Is this a 400 amp overhead service in a residential area ? Haven't seen too many of those.
2) If so, most of the POCO's that I deal with carry insulated barrel crimps on their truck that are suitable for up to 2/0 copper. They can't crimp onto 4/0.
3) If you've calculated for a 400 amp service then shouldn't the feeders for the "total" service have to be sized for 400 amps ?
4) If you've calculated for a 400 amp service how can you use a disconnect that is rated at 320 amps ?

Any 400 amp (or greater) services that I've done have been fed underground into a CT cabinet with a special POCO wired meter socket. Once you leave the CT cabinet and wire into 200 amp main disconnects you can use 2/0.

If I'm looking at this in a wierd way or not thinking "out of the box" would someone please say so and point me in the right direction ?
Click to expand...
It's a single phase 320amp meter socket. 80% of 400 is 320 so it can be used to meter a 400amp single phase service
 
jefftaman said:
This is a residential 400 amp overhead service, this guy has a christmas light display beyond belief. I have not seen the panel but I will call the guy on Monday to go take a look. He is stating one 200 amp breaker feeds one bus and the other 200 amp breaker feeds the other bus, the breakers are tied together. So theoreticaly each ungrounded SEC will never be subjected to more than 200 amps, which is why he arguing that he only needs 2/0. If this had a 400 amp main then it is a no brainer, but the two 200 amp mains is throwing me for a loop.
Click to expand...

Seems to me if this panel is really constructed this way, then it is only a 200amp panel. Even with a double pole breaker connecting both buses together there is still only a total draw of 200amp.
 
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