# Multiple mains in an enclosure revoked in 2020



## Southeast Power (Jan 18, 2009)

2020 NEC 230.71 "Revokes" multiple mains in a panel and must be in a separate enclosure.

This is going to be a problem where we have a meter main with two main breakers.
I have a project coming up where I have to "rework" one of these.
What are the chances our AHJ has adopted the 2020 version of NFPA 70?






The Six Disconnect Rule: The 2020 NEC revision has major impacts on electrical installations







www.ecmag.com


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## MHElectric (Oct 14, 2011)

The 2020 cycle is absolutely full of garbage rule changes. I hope the AHJ’s continue to keep modifying it with amendments and throwing out as much of it as possible.

Or better yet, don’t even adopt it.


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## SWDweller (Dec 9, 2020)

Your description is a meter main, and two feeder breakers, not 3 main breakers.
Turning off either of the feeder breakers does not turn off the service. Even turning them both off you still have power in the cabinet.
My understanding of electrical work does not allow for 2 mains unless they are on a double ended switchgear fed from 2 different substations.


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## MHElectric (Oct 14, 2011)

SWDweller said:


> Your description is a meter main, and two feeder breakers, not 3 main breakers.
> Turning off either of the feeder breakers does not turn off the service. Even turning them both off you still have power in the cabinet.
> My understanding of electrical work does not allow for 2 mains unless they are on a double ended switchgear fed from 2 different substations.


He’s talking about services that has 6-throws and no mains. This is now outlawed in the 2020 code. Everything now requires a main if your on the 2020 cycle.


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## matt1124 (Aug 23, 2011)

Cost be damned but all we need is a meter main combo with a 400 amp MCB that accommodates 3/0 double taps.

edit: milbank makes 400 combos, they are on the website. Can’t see what the load side lugs are though…


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## kb1jb1 (Nov 11, 2017)

matt1124 said:


> Cost be damned but all we need is a meter main combo with a 400 amp MCB that accommodates 3/0 double taps.
> 
> edit: milbank makes 400 combos, they are on the website. Can’t see what the load side lugs are though…


People here have to watch what equipment they use. Always check with the utility company and the electrical inspector. I have an issue with those 400 amp meter / disconnect units. The meter socket is not 400 amp rated and around here they are not approved. People from all over the country and Canada come to ET so watch what equipment and code cycle you are on. Personally I would like the 400 meter Mains combo. It beats working with CT cabinets or Trans A boxes.


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## VELOCI3 (Aug 15, 2019)

kb1jb1 said:


> People here have to watch what equipment they use. Always check with the utility company and the electrical inspector. I have an issue with those 400 amp meter / disconnect units. The meter socket is not 400 amp rated and around here they are not approved. People from all over the country and Canada come to ET so watch what equipment and code cycle you are on. Personally I would like the 400 meter Mains combo. It beats working with CT cabinets or Trans A boxes.


400 amp meter? I thought 200 was max then CT’s need to be used.


Sent from my iPad using Tapatalk


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## CMP (Oct 30, 2019)

Its a foolie 320A thru the meter.

Still need a CT cabinet for 400A


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## Almost Retired (Sep 14, 2021)

my poco only goes to ct above 400A
and yes its a 320A Continuous rated socket that is used for 400A

but it is always the same meter they use for 100A and up


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## Ostrich Society (Dec 14, 2021)

Our AHJ adopted the 2020 code but won’t enforce the 230 changes yet. Not until the manufacturers catch up and can supply compliant equipment. AHJ said the contraptions people were building to meet this rule were more dangerous than, you know…just doing what we have been doing.


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## Almost Retired (Sep 14, 2021)

Ostrich Society said:


> Our AHJ adopted the 2020 code but won’t enforce the 230 changes yet. Not until the manufacturers catch up and can supply compliant equipment. AHJ said the contraptions people were building to meet this rule were more dangerous than, you know…just doing what we have been doing.


Lo and Behold !!!
a smart inspector !!!
i knew there had to be some out there !!~~!


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## MHElectric (Oct 14, 2011)

Ostrich Society said:


> Our AHJ adopted the 2020 code but won’t enforce the 230 changes yet. Not until the manufacturers catch up and can supply compliant equipment. AHJ said the contraptions people were building to meet this rule were more dangerous than, you know…just doing what we have been doing.


That’s good. 

Theses codes are so driven by nonsense. I feel like only a select few of the changes that have happened in the last several code cycles have actually been about safety or better quality installations. Everything else is simply manufacture’s lobbying for contractors to have to use their more expensive products. And many of these products aren’t even available in many areas around the country.

In most cases, the ways things have been done for years and years now are the best and safest ways of doing things.


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## kb1jb1 (Nov 11, 2017)

VELOCI3 said:


> 400 amp meter? I thought 200 was max then CT’s need to be used.
> 
> 
> Sent from my iPad using Tapatalk


Yes I 100% agree that 200 amps is the max on a meter but apparently many parts of the country use the 320 amp meter for a 400 amp service. Here anything above 300 amps requires a CT or trans A.


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## Forge Boyz (Nov 7, 2014)

kb1jb1 said:


> Yes I 100% agree that 200 amps is the max on a meter but apparently many parts of the country use the 320 amp meter for a 400 amp service. Here anything above 300 amps requires a CT or trans A.


We used 320A bases all the time. I can't recall ever using a CT cabinet for a 400A service. I've even done 480V services with them. I think 320 continuous is fine. From what I have seen, if you run the service at that rating, you will likely see the breaker start tripping. Fuses maybe not, but a breaker isn't going to like sitting at 330A to 340A. I learned that the hard way.

Sent from my SM-G970U using Tapatalk


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## Southeast Power (Jan 18, 2009)

Forge Boyz said:


> We used 320A bases all the time. I can't recall ever using a CT cabinet for a 400A service. I've even done 480V services with them. I think 320 continuous is fine. From what I have seen, if you run the service at that rating, you will likely see the breaker start tripping. Fuses maybe not, but a breaker isn't going to like sitting at 330A to 340A. I learned that the hard way.
> 
> Sent from my SM-G970U using Tapatalk


Yup, we use 320s here all of the time, they even have a 600 that’s bolted in


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## Norcal (Mar 22, 2007)

I have a used Zinsco II (BR) 400A meter main w/ a 400A main breaker & distribution section, rated to take up to 225A BR breakers, most have 2-200A mains. It has a plugin meter socket.


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## matt1124 (Aug 23, 2011)

Norcal said:


> I have a used Zinsco II (BR) 400A meter main w/ a 400A main breaker & distribution section, rated to take up to 225A BR breakers, most have 2-200A mains. It has a plugin meter socket.


They did not think that was funny at the Eaton dealer when I asked for a double pole 60A Zinsco II after I saw you call them that last time 🤣🤣🤣


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## SteveBausch (8 mo ago)

Can someone point me to a history or discussion or "evolution" of this "one disconnect" rule?

My guess is it's a response to the locking or caging of meters by owners, property managers, landlords, etc to prevent the theft or swapping of meters, which prevents fire departments from pulling the meter to deenergize the house.

The idea being that the locking of meters cannot be stopped, so just give us a switch near the meter.

Right?

However, the alternate method is a Knox Box near the front door, holding the key to unlock the meter's lock. The fire department has a master key for the Knox Boxes in their jurisdiction, and that building's Knox Box has keys for emergency response.

Available in commercial and residential sizes.


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## kb1jb1 (Nov 11, 2017)

It is supposed to make it safer to work on a panel. One disconnect and the whole panel is dead. Prior to 2020, you can shut all 6 breakers off and the panel is still live. You can still have 6 disconnects but they have to be separate enclosures. Switchgear with separate buckets is ok.


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## hornetd (Oct 30, 2014)

SWDweller said:


> Your description is a meter main, and two feeder breakers, not 3 main breakers.
> Turning off either of the feeder breakers does not turn off the service. Even turning them both off you still have power in the cabinet.
> My understanding of electrical work does not allow for 2 mains unless they are on a double ended switch gear fed from 2 different substations.


Not quite. What is now required is that the busbars that supply the six disconnecting means must have a separate dead front and that each of the Service Disconnecting Means have their load terminals in a separate compartment. That is so that you can connect or disconnect any of the six circuits supplied from the 6 breakers without being exposed to energized terminals or conductors. I suspect that the dead fronts will be arranged so that you must turn the breaker off to be able to remove it.

Tom Horne


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