How not to install a Breaker Lock

[sceepe]

Saw this in a school on the main. I think the idea was that you have to trip the main, extend the lock, remove the key, and use that key to unlock the breaker they added for a backup generator feed. Somehow I don't think that's going to work too well.

 

[roger]

Saw this in a school on the main. I think the idea was that you have to trip the main, extend the lock, remove the key, and use that key to unlock the breaker they added for a backup generator feed. Somehow I don't think that's going to work too well.

View attachment 5383

This is a pretty common method of selectively choosing systems without the possibility of bucking heads, do a google search for "Kirk key"

Roger

 

[stevebea]

Saw this in a school on the main. I think the idea was that you have to trip the main, extend the lock, remove the key, and use that key to unlock the breaker they added for a backup generator feed. Somehow I don't think that's going to work too well.

View attachment 5383

Also used on 12470/480 substation so you cant close the HV side with a load.

 

[iwire]

I have worked with a number of these Kirk key maintenance bypass switches when we have installed larger UPS systems.

 

[Dilligaf1220]

Jim

Jim

Working with many types switches, GE, Westinghouse and Etc. most High Voltage primary and 480/277 or 208/120 secendary have this Kirk Key lock-out system. This is the only way to make it safe to work and switch.
Jim:roll:

 

[hillbilly1]

Walmart uses these extensivly, lots of grocery store chains too. Be careful though when hooking up a generator to these, as I have run across some that the electricians brought the utility in on the common tie side of the breakers, When the kirk key is brought over to the generator breaker, and energized, it powers the utility, instead of the building! Very dangerous! (This was a recent new installation that had been inspected to boot!)

 

[kwired]

Walmart uses these extensivly, lots of grocery store chains too. Be careful though when hooking up a generator to these, as I have run across some that the electricians brought the utility in on the common tie side of the breakers, When the kirk key is brought over to the generator breaker, and energized, it powers the utility, instead of the building! Very dangerous! (This was a recent new installation that had been inspected to boot!)

So what does the main breaker disconnect? Maybe I am not following what you are describing.

 

[zog]

Very common to see these, some of them can get pretty complex

 

[Cow]

Jeez, I could probably launch a nuclear missile easier than that!:grin:

 

[hillbilly1]

So what does the main breaker disconnect? Maybe I am not following what you are describing.

With this type of setup, both outputs of the breakers are physically tied together, with this tie feeding the load, if the utility is feed into this point, with the load connected to where the utility was supposed to be connected, the utility main will turn of the building, but the generator breaker when closed will feed the utility transformer instead of the building. This in turn will try to energize the POCO's lines, and if the lineman is lucky, it will trip, if he is not lucky.......well you know the rest of the story. Just like a homeowner backfeeding a panel without turning the main off.

 

[weressl]

Saw this in a school on the main. I think the idea was that you have to trip the main, extend the lock, remove the key, and use that key to unlock the breaker they added for a backup generator feed. Somehow I don't think that's going to work too well.

View attachment 5383

Although I have seen many Kirk-key mechanical interlocks, but this is the first time I've seen one with and external and extended shaft without the shaft actually locking INTO the blocked device. Even though it looks factory installed I would search for the documentation if it is actually designed and approved by and in the factory AND if it retains the UL listing. (I see a faint pencilmark @ the bolting screw, so it may be field installed and the shaft does not appaer to be completely vertical. On the other hand the UL label next to it maybe a special 'on floor' approval.

 

[LarryFine]

Jeez, I could probably launch a nuclear missile easier than that!:grin:

Yeah, I just saw War Games again recently, too.

 

[LarryFine]

I have worked with a number of these Kirk key maintenance bypass switches when we have installed larger UPS systems.

So, what's the setup? One key fits both locks, but can only be removed when the breaker is off, effectively an interlock?


Added:

... this is the first time I've seen one with and external and extended shaft without the shaft actually locking INTO the blocked device.

So, the concern is that removing the cover defeats the interlock?

 

[iwire]

So, what's the setup? One key fits both locks, but can only be removed when the breaker is off, effectively an interlock?

Yes, the one in the picture is a simple one.

A couple we have worked wih had mutiple sources, utility, genertor and could supply a UPS or bypass the UPS in case it was down.

In that case there were multiple keys, some indicator lights and a bunch of instructions all over the unit explaining how to work it all.

 

[kwired]

With this type of setup, both outputs of the breakers are physically tied together, with this tie feeding the load, if the utility is feed into this point, with the load connected to where the utility was supposed to be connected, the utility main will turn of the building, but the generator breaker when closed will feed the utility transformer instead of the building. This in turn will try to energize the POCO's lines, and if the lineman is lucky, it will trip, if he is not lucky.......well you know the rest of the story. Just like a homeowner backfeeding a panel without turning the main off.

That is basically what I thought you were describing. I have a hard time seeing that mistake being made very easily. Just having a one line diagram and taking a pretty casual look at it would catch the mistake pretty easily I would think. Otherwise equipment failures when it is tested for the first time would likely uncover it.