Kirk Key Double ended swichgear

[bowhunter4life]

Can anybody tell me where I may find the NEC requirement where a Kirk Key is required? Let say we have two utility feeds from seperate transformers 480 volts to a single 2500 amp switch gear. As I see it, only signage is required to protect someone from energizing both ends.

ThX Mike

 

[augie47]

Excellent question
(I have found no requirement)

 

[jim dungar]

As I see it, only signage is required to protect someone from energizing both ends.

Key interlocks are a design issue. They are not required by the NEC.

 

[iwire]

Key interlocks are a design issue. They are not required by the NEC.

This seems very odd that the NEC would allow just signage to prevent a potentially huge fault.

If I was an inspector I might cite 110.3(A) and let the EC decide what method would prevent a fault.

 

[templdl]

This seems very odd that the NEC would allow just signage to prevent a potentially huge fault.

If I was an inspector I might cite 110.3(A) and let the EC decide what method would prevent a fault.

I've never submitted a proposal and/or built a double ended either LV or MV switchgear where key interlocks were not provided. I would think that to not provide double ended swgr with out them would be highly negligent and with almost all certainty would be subject to a mega lawsuit should an incident occur because they were not included in the design.
It's something that you does do as a matter of good practice.

 

[jim dungar]

I've never submitted a proposal and/or built a double ended either LV or MV switchgear where key interlocks were not provided.

You have led somewhat of a sheltered life.

I have seen several installations where the customer wants a 'make before break' closed transition transfer.

As long as the two sources are set up for paralleling (e.g. synched and phased) and rated correctly there is not much of an issue.
I do often recommend monitoring relaying for these applications.

What dothe NEC and NFPA 70E say about being qualified?

 

[puckman]

SWITCHGEAR LABEL QUESTION

SWITCHGEAR LABEL QUESTION

We have a switchgear with 2 main breakers used in a alternate way , one on each end of the switchgear using a kirk key system . this is a one service feed with the two cb labeled #cb1 and cb#2. My question is on our arc flash labels the #1 cb is listed as EQPT. SWGR BUS 1 #2 cb is listed EQPT. SWGR- BUS 2
OCPD POCO FUSE OCPD SWGR- CB 2

It seems the cb # 2 ocpd should also be listed as the poco fuse .
Is the information on the label a typo or is it correct ?
THANK YOU ALL.
CAN'T MOVE OR DELETE THIS TREAD , SORRY FOR POSTING HERE........

 

[iwire]

As long as the two sources are set up for paralleling (e.g. synched and phased) and rated correctly there is not much of an issue.

The OP did not indicate it was set up for that and if it was I don't think he would be concerned.

But I am out of my element so I could be way off base.

 

[rbalex]

The OP did not indicate it was set up for that and if it was I don't think he would be concerned.

But I am out of my element so I could be way off base.

If it wasn't set up as Jim described, it's in violation of Section 110.9.

I'm not a fan of key interlocks. I've been in more than a few facilities where every key interlock has a key inserted and nothing prevents having all sources being paralleled - including signs. It's not too unusual for multiple utility sources to be adequately "synced" upstream and the potential consequences overlooked when paralleled.

 

[iwire]

I'm not a fan of key interlocks. I've been in more than a few facilities where every key interlock has a key inserted and nothing prevents having all sources being paralleled -

Now you really have me baffled, :? any kirk key interlock system I have touched specifically prevents paralleling sources. That is the entire reason they are installed.

I run into them in some data centers for UPS bypass panels and such.

You would have to have or make an extra set of keys which in mind is equivalent to someone using tools to bypass any safety item.

 

[GoldDigger]

I remember the radiation safety setup at a lab where I worked. At critical areas there were multiple key lock switches.
Before entering a hazardous area you turned off one of the switches and removed the key. The switches both disabled the radiation source and lit an indicator in the control room.
Everybody going in had to take and carry an individual key.
Once all of the keys were back and the switches on, you knew the area was clear.
Similar to the brass board at small mines.


Tapatalk...

 

[rbalex]

...

You would have to have or make an extra set of keys which in mind is equivalent to someone using tools to bypass any safety item.

Yep, that's exactly what happens.

 

[jim dungar]

The OP did not indicate it was set up for that and if it was I don't think he would be concerned.

But I am out of my element so I could be way off base.

My reply to the OP was that keys were a design decision.
My example of equipment without keys was for Templdl, who said he had never been involved in the sale of a 'keyless' lineup.

I have had the same experience as Rbalex, maybe 25-30% of keyed systems I have seen, involve some mismanagement of the keys.

 

[zog]

Now you really have me baffled, :? any kirk key interlock system I have touched specifically prevents paralleling sources. That is the entire reason they are installed.

I run into them in some data centers for UPS bypass panels and such.

You would have to have or make an extra set of keys which in mind is equivalent to someone using tools to bypass any safety item.

Actually every lock comes with a key when shipped, it is up to the installer, commisioning guy, or owner of the system to remove (And destroy, or at least hide) the proper keys for the interlock system to work properly.

I have removed plenty of keys during commisioning and have often found all keys installed on systems that were in service for decades. The worst related thing I ever saw was going to shut down some substations at a Automotive assembly plant, the engineer tossed the plant electrician that was to do the switching a huge key ring with every kirk key for the plant on it and told him to go do the switching order. Stopped him right there and explained how they were supposed to work and the dangers of not having it set up right.

 

[templdl]

Now you really have me baffled, :? any kirk key interlock system I have touched specifically prevents paralleling sources. That is the entire reason they are installed.

I run into them in some data centers for UPS bypass panels and such.

You would have to have or make an extra set of keys which in mind is equivalent to someone using tools to bypass any safety item.

Actually every lock comes with a key when shipped, it is up to the installer, commisioning guy, or owner of the system to remove (And destroy, or at least hide) the proper keys for the interlock system to work properly.

I have removed plenty of keys during commisioning and have often found all keys installed on systems that were in service for decades. The worst related thing I ever saw was going to shut down some substations at a Automotive assembly plant, the engineer tossed the plant electrician that was to do the switching a huge key ring with every kirk key for the plant on it and told him to go do the switching order. Stopped him right there and explained how they were supposed to work and the dangers of not having it set up right.

Ditto! Every lineup that I did and shipped were keyed properly for a specific sequence to happen. For example a breaker that was closed
Could only be opened with the key in the lock. Unless the breaker was opened the key could not be removed. Once you had that key in your hand then you could proceed to a second breaker that was open and insert the key on that lock which allows you to close that breaker. The key remains captive until the breaker is opened.
I've specified system that involve a sequence of 5 different keys as I can recall. Both kirk key and superior very close control and records of the keys that they supply. There should be no "extra" keys. If there were extra keys ordered after delivery by the owner for some reason they should be kept in a safe to prevent abuse. There is no need to have duplicate key running around loose.

 

[iwire]

You would have to have or make an extra set of keys which in mind is equivalent to someone using tools to bypass any safety item.

Yep, that's exactly what happens.

Which in my mind is not a problem with Kirk keys but training.

To me it is exactly the same as replacing fuses with higher ratings.

 

[iwire]

Actually every lock comes with a key when shipped, it is up to the installer, commisioning guy, or owner of the system to remove (And destroy, or at least hide) the proper keys for the interlock system to work properly.

I have removed plenty of keys during commisioning and have often found all keys installed on systems that were in service for decades. The worst related thing I ever saw was going to shut down some substations at a Automotive assembly plant, the engineer tossed the plant electrician that was to do the switching a huge key ring with every kirk key for the plant on it and told him to go do the switching order. Stopped him right there and explained how they were supposed to work and the dangers of not having it set up right.

Which again is a training issue not an issue with the system don't you think?

 

[zog]

Which again is a training issue not an issue with the system don't you think?

Yes

 

[rbalex]

Which again is a training issue not an issue with the system don't you think?

Of course it's a traing issue - just as bypassing any safety system is. However, key systems are easier to bypass than hard wired interlocks for most operators that are trained only the switching steps.

I just finished a key interlock project that I didn't design, but helped commission. The system was primarily a lineup of LISs that were frequently operated. The client's operators were already discussing how to "simplify" the operation when I left. I did notify the client's management.

 

[pfalcon]

NPFA70E 120.2(D)(2)(1) Complex Lockout/Tagout procedure required due to multiple energy sources.

The OP condition presents a recognized hazard and therefore requires proper evaluation for its hazards. A specific solution is not mandated but is determined by risk analysis.