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#67221 - 06/29/06 09:36 PM Parallel Breakers?  
master66  Offline
Member
Joined: Apr 2002
Posts: 257
Masontown, PA, USA
Today I asked for a quote on a 400A 2-gang meter socket with disconnects. What I got was a quote on a 400A 2-gang meter socket with (2) 200A breakers in each section. I was told that feeding a 400A MLO panel with (2) 200A paralleled breakers was OK. These breakers operate independent of each other and are factory installed in the meter socket section.

I have never come across this set-up before. According to 240.8 it seems to be OK. It just doesen't sound right to me.

Have any of you guys done this or seen this done before?

Brian


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#67222 - 06/29/06 09:49 PM Re: Parallel Breakers?  
CaOperator  Offline
Member
Joined: Apr 2003
Posts: 60
Los Angeles, CA, USA
If I am understanding this set up, I would be worried about keeping the neutrals seperate between the services. Or if they are truly parallel I would think this would only have a 200 Amp capacity before tripping.

Your right, it does not sound right.


#67223 - 06/29/06 09:52 PM Re: Parallel Breakers?  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Sounds like 2 200a panels from that, not a single feed at 400a from it...... Unless they are linked in some way? Many class 320/400 resi services are like that.

From the commentary of 240.8
Quote
Section 240.8 prohibits the use of fuses or circuit breakers in parallel unless they are factory assembled in parallel and listed as a unit. Section 404.17 prohibits the use of fuses in parallel in fused switches.
It is not the intent of 240.8 to restore the use of standard fuses in parallel in disconnect switches. However, 240.8 recognizes parallel low-voltage circuit breakers or fuses and parallel high-voltage circuit breakers or fuses if they are tested and factory assembled in parallel and listed as a unit.


Either way it sounds odd that a 400A 2-gang meter socket would have 4 200a CB's.... 800A of combined protection with no diversity on a 400A meter?

Got a model and make?


Mark Heller
"Well - I oughta....." -Jackie Gleason

#67224 - 06/29/06 09:58 PM Re: Parallel Breakers?  
master66  Offline
Member
Joined: Apr 2002
Posts: 257
Masontown, PA, USA
It would be a GE meter socket. He was supposed to email a cut sheet.

You guys are right. What would keep someone from using (4) 200A breakers for a 800A subfeed?

I thought about the (2) 200A panels. I have to run the numbers to see if would be cheaper.

As it stands. The parallel breaker set-up is about $1000.00 cheaper than a single 400A main.

Brian


#67225 - 06/29/06 10:17 PM Re: Parallel Breakers?  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
At 200A CB's change dramaticaly in class, and frame.


Mark Heller
"Well - I oughta....." -Jackie Gleason

#67226 - 06/29/06 11:36 PM Re: Parallel Breakers?  
SolarPowered  Offline
Member
Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Ya, two 200A breakers are going to be around $1000 cheaper than one 400A breaker. Once you get past 200A, the price goes up pretty close to exponentially with ampacity.

If the documentation with the equipment says that it's intended for a 400A feed, then it's OK. But, I think the chances are upwards of 90% that this setup is intended to feed two 200A MLO panels, and isn't listed to feed a single 400A panel.

[This message has been edited by SolarPowered (edited 06-30-2006).]


#67227 - 07/01/06 06:13 AM Re: Parallel Breakers?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
if they are truly parallel I would think this would only have a 200 Amp capacity before tripping.


Two 200 amp over current devices in parallel will provide 400 amps of capacity.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#67228 - 07/01/06 11:43 AM Re: Parallel Breakers?  
Dave T  Offline
Member
Joined: Jan 2005
Posts: 155
Waukesha, WI, USA
You don't parallel breakers perod, or LV fuses that I am aware! You can discuss if in theory all that you want but it can not be applied.
The only area where I have see fuses paralled is in medium voltage application where a specific fuse holders have been provided and ratings has been given for the combination.


#67229 - 07/01/06 12:14 PM Re: Parallel Breakers?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Dave you are correct we can not parallel OCPs in the field. However some equipment comes that way.

My 200 amp GE service panel uses four single pole 100 amp breakers with two in parallel to provide two legs of 200 amp capacity.

I also find fuses in parallel in some equipment.

My point was it works although it is generally an NEC violation.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#67230 - 07/01/06 02:59 PM Re: Parallel Breakers?  
master66  Offline
Member
Joined: Apr 2002
Posts: 257
Masontown, PA, USA
Yesterday I called Tim Croushore of Allegheny Power. Tim is or was on a Code making panel (Don't know which one but his name is in the code book).

After I explained the situation he agreed that parallel breaker would not be compliant in this situation. He said that if the breakers were installed in the panel feeding a split buss it would be OK. That was not my case.

I told the supplier. The supplier wanted to get more info. He did say again that he has sold this set-up before and it was passed.

We'll see where this goes but we all learned something. I love it when that happens!

Brian


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