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Kirk Key Interlock

Kirk Key Interlock

Kirk Key Interlock

(OP)
Trying to figure out the simplest design for the following:
There is an existing hospital with a 2000A 480V service going in to a GE fused disconnect with GFP and test button.  The customer is being required to install an alternate power quick connect in which the customer decided to install at the service for the whole building.  I realize I need to protect from back feeding the utility and was thinking of installing a mechanical kirk key interlock box of some type.  One of my questions is since this will be ahead of the fused service disconnect would I have to  put an over current protection device (OCPD) in with the kirk key system or can I find a way to get around this?  Would I be required to have an OCPD in the quick connect circuit too or can I relay on the alternate power source to have it (I wouldn't think so, but just wondering)?  As soon as I put any additional OCPD in the circuit I will be required to do a coordination study for the whole service and feeder system and I don't want to have to burden the custom with the cost and time of that.  I am also looking at a way to do a simple magnetic lockout on the alternate source based on the position of the position of the service disconnect, but can't figure out how to make it fool proof.  My preferred solution is to put a simple mechanical kirk key or other interlocking system in ahead of the utility and not have to do any additional OCPD and use the existing OCPD, but think it wouldn't fly.
 

RE: Kirk Key Interlock

Kirk key interlocks are mechanical locks that are applied to the existing switches. They are most often applied to the switchgear when it is built. Retrofitting may require an outage to accomplish an acceptable installation. The mounting screws should be installed from the back of panels to be hidden when the switchgear is closed. Bolt holes may have to be located and drilled to accommodate the lock bolt.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Kirk Key Interlock

I suspect you can field install a Kirk Key interlock on the existing main fused disconnect, and tie this to an interlock on a new fused switch on the alternate source.  

I don't think you're going to be able to put an unprotected transfer switch or other device ahead of the main disconnect.   

David Castor
www.cvoes.com

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