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How To Tie Two 200 amp Panels Together

Slick 50

Registered
I am wanting to tie two 200 amp single phase panels together on the load side. Both panels are fed from a single meter. My thoughts are to use number 2 wire to each panel with a breaker at each end in the panel.
Is there any problem with doing this to tie the panels together?
Thanks for any help.
Rick
 

Gary Bahre

Subscriber
Last Subscription Date
12/30/2019
Re: How To Tie Two Panels Together

Slick; In the area that I live in the power co. uses a 320 amp service, this feeds 2, 200 amp box's from one meter. Check with your power supplier to see what box's and other things you need to do this. Gary
 

Slick 50

Registered
Re: How To Tie Two Panels Together

Thanks Gary,
The panels are already in and wired. They are Square D QO panels. Hoping to prove or disprove my thoughts about phasing. Does it matter what leg is tied to a particular bus bar? I'm thinking it does but not sure.
Thanks,
Rick
 

Power

Registered
Re: How To Tie Two Panels Together

Why do you want to do this?
Violates national electric code.
Will not be approved by AHJ.
You would have 2 feeds into a panel @200 amps each - in excess of manufacturer's ratings for panel
You would have 2 disconnects- one top, one bottom
When something goes wrong, insurer will not cover it.
 

Jim Rankin

Registered
Age
58
If all you want to do is experiment that when you connect one "phase" to the other "phase", you do indeed have a short circuit, go ahead.

You can do the same thing from any 2 pole breaker in each box, no need to do it with expensive 200 amp breakers. Take a volt meter, test the two breakers respective terminals and when you find the ones that test 0 volts between them, those are in phase, If you test two poles and get 240 volts, those are out of phase. Confirm that each breaker is indeed turned ON by testing voltage to neutral after you test voltage between the two breakers.

With single phase panels, no it doesn't matter which line is connected to which bus bar. If it was a 3 phase panel, then I could see that it might be nice to have phaser rotation be A, B, C in both panels. However, this would not necessarily be the same phases to the same bus bars. Could be, but not necessarily the same. A,B,C is the same as C,A,B or B,C,A but is opposite of C,B,A etc...
 

Slick 50

Registered
Jim,
Thank you so much for the response. The tie wire between panels is actually number 4, memory not always so good. As mentioned, on each end of that wire will be breakers, in this case, 90 amp. I had planned on checking continuity from the meter to each leg on the tie for proper line up before energizing. We are still about a month away from powering up the house.
Thanks again,
Rick
 

grif

Registered
Was your phasing question whether or not you had three phase available? Or if you really just had two panels of center tapped 240 single phase?
 

Slick 50

Registered
The question was about single phase 240 volt only. The limit with 42 spaces per panel is what got me, needed a few more spaces. It's all about powering the panels with a generator and the main feed opened with a disconnect.

Thanks for the quick help, very much appreciated.
Rick
 

davidradio

Registered
i would not do this both mains have to be off to prevent feed back to line

i would only use two 200 amp tranfer switches only that way
there can be no feed back if mains are left on

one other option would be to put an inter lock in both panels
from interlock.com that way there will be no feed back to power line

and if power is restored
with main on you will have a mess burnt up generator and possible
fire in house and insurance will not cover this as voliation of nec
big time
 

grif

Registered
Sounds like the same configuration I've got, except I've got lots of slots left, my issue is the two panels are 100 feet apart. I've about decided to put the jolly green giant transfer switch right at my side of the meter, and I've got critical load on each panel. (poor planning on my part).
 

jht1057

Registered
Slick,

You can tie panels together and it is approved by code.
The panel that the meter feeds would be the "main" panel, the second panel would be the "sub" panel.

When wiring mains to the bus bars, I always kept the white on the right.

Jim
 

Power

Registered
You can tie panels together and it is approved by code.
The panel that the meter feeds would be the "main" panel, the second panel would be the "sub" panel.

That's ok, but then the most amperage available is the rating of the main panel breaker - 200 amps. Also, there are restrictions on the size of sub panel breaker. It cannot equal main.
 

Tencubed

Registered
Sounds to me like it's Jerry Rig time on this project.

Your home owners insurance and a lot of other problems can get involved really quick.

I'd sure suggest you get a licensed electrician to take a look at your project and give you the advice you are seeking.

Just my opinion of course but what any of us say about your project is worth every dime you're paying for it.

Mike
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
The question was about single phase 240 volt only. The limit with 42 spaces per panel is what got me, needed a few more spaces. It's all about powering the panels with a generator and the main feed opened with a disconnect.

Thanks for the quick help, very much appreciated.
Rick
If all you need are a few more spaces for circuit breakers, can't you just use a few piggyback breakers? Or as someone suggested, add a subpanel for a few extra circuits.
 

Craig Mattson

Registered
I would suggest the piggyback sub panel method. I have done it both ways much easier to get the inspector to ok it that way. Good luck
 

Daverepair

Registered
Are you talking about connecting a generator to 2 200 amp panels that are fed in parallel from one meeter. See drawing attached. If so, BAD IDEA
 

Attachments

Daverepair

Registered
Lots of room for problems. How about two transfer switches, one before each panel or one big switch right after the meter. That would requirer a big generator.!00kw I believe.
 

armandh

Sponsor
Last Subscription Date
09/02/2010
MY HOUSE:

the entry panel with bonding point and where the mains disconnect
is interlocked with the generator feed breaker.
there is also a 125 amp breaker feeding a sub panel
all sub panels must have an isolated neutral

the feed from the portable generator is 4 wire
with the neutral isolated from the generator frame.

if you have a permanent generator installed
then a transfer system [or manual switch] is required

code now requires a disconnect between the meter and transfer

if the permanently installed generator feeds more than one transfer
it must have overload protection correct for each line and be bonded, thus
requiring all transfers to be 3 pole and following panels have isolated neutrals
 
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armandh

Sponsor
Last Subscription Date
09/02/2010
225 amp
http://www.smokstak.com/forum/attachment.php?attachmentid=11399&d=1158413795

turn off main breaker causing the
breaker lever alignment with notch in plate
slide plate right to lock mains breaker off and that
clears an area for gen breaker to be moved right to on
attempts to disengage the lock flip the gen breaker off

I only load the generator to a 12.5Kw max [50 Amp]
well below generac's alleged 17.5 continuous and 26 surge KW
and as these screamers are not likely to out live us, for a back up,
I have an 1800 rpm '64 vintage k582 powered 7.2 [real] Kw homelite [1.0 pf]
one can load it until the breakers open, and at about 3 hp/kw it is not even working hard
http://www.smokstak.com/forum/attachment.php?attachmentid=22611&d=1188565666
 
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