Does a Kirk key interlock need to be installed?

[Isaiah]

We have a 480V SWGR that gets input from 2-500kVA Emerg generators when there is an outage.
There is no ATS and the two generators feeders terminate in 1600A CB. There is also a MCB that gets its supply from a normal 480V source.
They want to manually close 1600A CB when there’s a outage (which doesn’t lineup with Nec 700 or 701).
In addition there is no kirk-key interlock between the MCB and the feeder CB.
There seems to be multiple code issues here


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[don_resqcapt19]

It doesn't sound like either 700 or 701 apply to this installation.
I believe 702 does, and 702.5(A) requires transfer equipment. The 2026 will also permit interlock equipment. Breaker interlocks are commonly used and accepted under the 2023 code and older codes.
I would require some type of interlock and for your example, about the only thing that would work is a kirk-key system.

It looks like you are paralleling two generators? What are you using for paralleling equipment?

 

[Isaiah]

It doesn't sound like either 700 or 701 apply to this installation.
I believe 702 does, and 702.5(A) requires transfer equipment. The 2026 will also permit interlock equipment. Breaker interlocks are commonly used and accepted under the 2023 code and older codes.
I would require some type of interlock and for your example, about the only thing that would work is a kirk-key system.

It looks like you are paralleling two generators? What are you using for paralleling equipment?

Thanks Don
They’re having trouble syncing the paralleled feeders from the Generator CBs to the SWGR BUS…but are you saying that under 702, the breaker interlocks are not actually required?
Using the the 2020 NEC


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[don_resqcapt19]

Thanks Don
They’re having trouble syncing the paralleled feeders from the Generator CBs to the SWGR BUS…but are you saying that under 702, the breaker interlocks are not actually required?
Using the the 2020 NEC


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The 2020 & 2023 requires transfer equipment and does not permit interlocks. In the case of breaker locks, which accomplish the same thing as a kirk-key, most AHJs permit them.

702.5(A) General.
Transfer equipment shall be required for all standby systems subject to the requirements of this article and for which an electric utility supply is either the normal or standby source. Transfer switches shall not be permitted to be reconditioned.

I would permit an interlock system of some type for this, but some AHJs would require actual transfer equipment as stated in the code.

 

[hillbilly1]

The 2020 & 2023 requires transfer equipment and does not permit interlocks. In the case of breaker locks, which accomplish the same thing as a kirk-key, most AHJs permit them.


I would permit an interlock system of some type for this, but some AHJs would require actual transfer equipment as stated in the code.

You know who pushed that through! Transferswitch manufacturers!

 

[Isaiah]

The 2020 & 2023 requires transfer equipment and does not permit interlocks. In the case of breaker locks, which accomplish the same thing as a kirk-key, most AHJs permit them.


I would permit an interlock system of some type for this, but some AHJs would require actual transfer equipment as stated in the code.

Great feedback Don as always!


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[jim dungar]

The 2020 & 2023 requires transfer equipment and does not permit interlocks.

Where does it specify key interlocked equipment as not being allowed?
Key interlocks are a type of mechanical interlock.
Relay/electronic interlocked paralleling/transfer equipment has been used for decades.
Neither of these types of transfer equipment are equal to simple electrical interlocks.

 

[Isaiah]

It doesn't sound like either 700 or 701 apply to this installation.
I believe 702 does, and 702.5(A) requires transfer equipment. The 2026 will also permit interlock equipment. Breaker interlocks are commonly used and accepted under the 2023 code and older codes.
I would require some type of interlock and for your example, about the only thing that would work is a kirk-key system.

It looks like you are paralleling two generators? What are you using for paralleling equipment?

Since these two generators are paralleled and terminate in a single CB at the SWGR, I assume they must also conform to 705?


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