# Service entrance manual transfer switch



## Etwo (Mar 22, 2021)

What is the best way to design/install service entrance manual transfer switch.

my plan is to intercept the secondary feeder and feed the manual transfer switch. Then from manual transfer switch to the main distribution panel.

What is the best way you guys design/install this service entrance manual transfer switch.


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## micromind (Aug 11, 2007)

What voltage/phase/amperage is the service?

Does it have one main breaker or more than one?


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## Southeast Power (Jan 18, 2009)

Etwo said:


> What is the best way to design/install service entrance manual transfer switch.
> 
> my plan is to intercept the secondary feeder and feed the manual transfer switch. Then from manual transfer switch to the main distribution panel.
> 
> What is the best way you guys design/install this service entrance manual transfer switch.


Just by definition, using an SE rated ATS is typically replacing the main.
You can use one on the feeder side if that’s what you have and that’s your question.


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## Etwo (Mar 22, 2021)

micromind said:


> What voltage/phase/amperage is the service?
> 
> Does it have one main breaker or more than one?


The existing main distribution panel is 400A, 480/277V, 3phase and it has main breaker


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## Etwo (Mar 22, 2021)

Southeast Power said:


> Just by definition, using an SE rated ATS is typically replacing the main.
> You can use one on the feeder side if that’s what you have and that’s your question.


Instead of replacing the main. I will do retrofit manual transfer switch, the double throw with main breaker and generator breaker

when you say,”you can use one on the feeder side” let me give an example, let’s say the transformer is feeding the main underground, how would you approach this?


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## micromind (Aug 11, 2007)

Etwo said:


> The existing main distribution panel is 400A, 480/277V, 3phase and it has main breaker


How is the 400 amp main connected to the busses?

I'm not sure but I believe that anything downstream of the main breaker is not the service, it is a feeder. If true, a basic 600 volt 400 amp double throw switch will be ok. 

Isolating the load side of the main from the busses and getting enough wire bending space could be a problem.


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## Etwo (Mar 22, 2021)

micromind said:


> How is the 400 amp main connected to the busses?
> 
> I'm not sure but I believe that anything downstream of the main breaker is not the service, it is a feeder. If true, a basic 600 volt 400 amp double throw switch will be ok.
> 
> Isolating the load side of the main from the busses and getting enough wire bending space could be a problem.


I am not sure but I believe the 400A main is connected to the panel bus, the main has couple of breakers that feed sub panels.

this new retrofit double throw manual transfer switch will become main and the existing main will become sub panel


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## kb1jb1 (Nov 11, 2017)

Maybe I am wrong but do they make a " Service Rated" manual transfer switch for 400 amp, 480/277 volts? You need a service disconnect between the transfer switch and the serving utility. As SE Power said above a Service Rated ATS might be better and cheaper.


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## Etwo (Mar 22, 2021)

kb1jb1 said:


> Maybe I am wrong but do they make a " Service Rated" manual transfer switch for 400 amp, 480/277 volts? You need a service disconnect between the transfer switch and the serving utility. As SE Power said above a Service Rated ATS might be better and cheaper.


Yes squareD, Eaton have them. The manual transfer switch comes with Main breaker for the utility side and Generator side


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## SteveBayshore (Apr 7, 2013)

Is there room to add another large frame breaker in the main panel? I have done quite a few by adding a load breaker (sized to the generator) in the main panel and back feeding that breaker from the generator and installed a Kirk Key interlock system between the existing main and the back fed breaker. I have Kirk Lock samples in my office if you want to see what they look like.


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## Etwo (Mar 22, 2021)

SteveBayshore said:


> Is there room to add another large frame breaker in the main panel? I have done quite a few by adding a load breaker (sized to the generator) in the main panel and back feeding that breaker from the generator and installed a Kirk Key interlock system between the existing main and the back fed breaker. I have Kirk Lock samples in my office if you want to see what they look like.


This is very interesting. I didn’t know you can do that. Can you please share the Kirk lock sample. Thank you


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## kb1jb1 (Nov 11, 2017)

Be careful with changing the design of a panel and adding devices. It might void the UL listing.


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## SteveBayshore (Apr 7, 2013)

Etwo said:


> This is very interesting. I didn’t know you can do that. Can you please share the Kirk lock sample. Thank you


Here are pictures of two of many different stiles of Kirk Locks. One pic shows the bolts extended and the other shows the bolts retracted. Keys are only removable in one position. Only one key for each pair of locks per project are supplied. Factory keeps a record of the project and of lock and key serial numbers. All lock bolts are custom sized for the application. I'm trying to locate pictures of an installation now. I'll get back on later, hopefully with a picture.
Steve Z


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## SteveBayshore (Apr 7, 2013)

I guess I should attach  pictures.


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## kb1jb1 (Nov 11, 2017)

I was on a job where the factory install kirk key locks were not installed correctly and it was possible to have both on at the same time. Also the original electrician did not have the phases correct. He had the right rotation but the colors were wrong. It was a good thing the MCCs were not put into service.


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## SteveBayshore (Apr 7, 2013)

OK, picture of Kirk Locks installed. We were 1/2 way through the project when owner wanted to add a portable generator connection to the site. Panel on right side was already installed and energized, 800 amp main breaker on the bottom left of the panel. I added a 400 amp panel on the left and relocated all essential circuits to the new panel. 400 amp breaker, just above the 800 amp main breaker, feeds the essential panel and has a Kirk Lock with the long bolt facing down. The bolt is retracted in normal (now) and the breaker can be operated on or off but the bolt cannot be extended unless the breaker handle is off. Once the breaker is off and the bolt extended it stops the breaker from being turned on and the key can be removed. It now can be used to operate the second lock, the one on the generator breaker in the essential panel on the left, bottom left breaker. As pictured now, the bolt is extended and is stopping the generator breaker from being turned on. Essential panel is same physical dimensions main panel for visual purposes. Once the bolt on the generator breaker is retracted, and the breaker is operable, the key is not removable from the lock. Square D supplied







all of the necessary components per my design for field installation.


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