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 Post subject: Apparent Contradiction of Two Informational Notes of NFPA 70E 130.7
PostPosted: Thu Jun 21, 2012 9:18 am 
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Informational Note No. 2 of 130.7 (a) establishes:

Statement: that "normal operation" of "enclosed" electrical equipment si not likely to expose the worker to an electrical hazard if:

Condition: The electrical equipment has been properly installed and maintained by a qualified person.

Lets assume the condition is satisfied. That is, the equipment has been installed and maintained properly.

Question 1: What is normal operation? Is it for example, opening or closing the main circuit breaker (i.e 4,000 A circuit breaker) from a service panel (as defined in the NEC) a normal operation? If it is, NFPA 70E Informational Note No. 2 from 130.7 (A) considers this interaction as one that will be as not likely to expose the worker to an electrical hazard and therefore should not wear PPE.

Informational Note No. 2 of 130.7(C)(15) establishes:

Statement: that in most cases "closed doors do not provide enough protection to eliminate the need for PPE if:
Condition: the state of the equipment is know to readily change (i.e. doors open or close, breackers are racked in or out.

Lets assume that the condition is satisfied. That is, we know that there is a lot of activity in the electrical equipment, we know that people are constantly opening and closing doors and frequently racking breakers in and out.

Question 2: When we approach this equipment with the doors closed to interact with it (i.e. operate the main circuit breaker, obviously without exposing any energized component by opening doors or taking covers off), then we would need to wear PPE?

Question 3: If racking breakers in and out is a normal operation and is done with the equipment enclosed on a panel that has been maintained and installed properly and that we know that its states readily changes, then which of the two informational notes takes precedence, do we need or do not need PPE?


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PostPosted: Thu Jun 21, 2012 1:03 pm 
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Racking breakers is one of the activities most likely to cause an arcing event.


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PostPosted: Thu Jun 21, 2012 1:05 pm 
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JBD wrote:
Racking breakers is one of the activities most likely to cause an arcing event.

I understand. And I believe it is. But I am after the interpretation of the standard.


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PostPosted: Thu Jun 21, 2012 3:21 pm 
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Good luck on interpretation of the standard.

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What is normal operation? Is it for example, opening or closing the main circuit breaker (i.e 4,000 A circuit breaker) from a service panel (as defined in the NEC) a normal operation? If it is, NFPA 70E Informational Note No. 2 from 130.7 (A) considers this interaction as one that will be as not likely to expose the worker to an electrical hazard and therefore should not wear PPE.

The definition of arc flash hazard states that examples of this are contained in the tables. That's informational note #2. However, it doesn't really state what is "normal" and what is "abnormal" operation. Since the conclusion from note #1 is that it is anything where there is not a hazard, it would be anything in the table that is listed as H/RC 0, except that this gets confusing for 240 V panels where H/RC 0 doesn't seem to match anything else, nor with >1 kV equipment where they use H/RC 2 instead. The tables were developed in a committee doing a risk assessment. Without details of their assessment methodology, you can't glean the answers you seek. In the articles section I posted an alternative that gets to an answer but requires you do perform your own risk assessment and go 100% away from the tables.

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When we approach this equipment with the doors closed to interact with it (i.e. operate the main circuit breaker, obviously without exposing any energized component by opening doors or taking covers off), then we would need to wear PPE?


Again, no answers from 70E. You must do a risk assessment for yourself. The only answer you get in 70E is to use the provided tables. If you are doing your own engineering risk assessment which they recommend and in many cases require, you must intrepret this for yourself. Some folks say no. Others say yes. I say look at the probability of an arcing fault in your facility and also use industry average data from IEEE as guidance.

What I will say is this. Getting hung up on whether the doors are closed or not doesn't matter EXCEPT for arc resistant gear which uses the doors as protection. For every other situation, IEEE 1584 and other arc flash incident energy calculation methods give ZERO credit for doors being closed and latched. What you have to look at is first do you have any reason to believe whether or not the equipment is not in a fully functioning condition such as after it has faulted. Second, look at the installation and maintenance of the equipment...are you following industry standards or a looser/tighter standard based on an engineering assessment. Third, what is the expected probability that an arcing fault occurs and is this a tolerable risk. Your answers can be directly applied to any number of existing risk assessment procedures out there to get an answer. Hint: the answer is pretty much what you are trying to ask for except for drawout gear that has a much higher incident rate of failures and arcing faults.

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If racking breakers in and out is a normal operation and is done with the equipment enclosed on a panel that has been maintained and installed properly and that we know that its states readily changes, then which of the two informational notes takes precedence, do we need or do not need PPE?


Again, no answers from 70E. Again, see previous answer.


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PostPosted: Mon Jun 25, 2012 11:07 am 
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PaulEngr wrote:
-snip-
What I will say is this. Getting hung up on whether the doors are closed or not doesn't matter EXCEPT for arc resistant gear which uses the doors as protection. For every other situation, IEEE 1584 and other arc flash incident energy calculation methods give ZERO credit....
-snip-.


We have asked the MANUFACTURER of arc-resistant MV-gear: Please state in writing what credit can we take for arc-resistant gear? The asnwer was, in short: none.


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PostPosted: Mon Jun 25, 2012 1:54 pm 

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130.7 (A) Informational note 2 is in regards to normal operation and even though breakers are opened or closed regularly it is not normal operation, the normal operation is to provide power and interrupt it in the event of an over current condition. The fact that personnel are interacting with the gear to change it's state makes all the difference.
130.7(c)(15) informational note 2 clarifies that changing the state of the equipment (opening or closing doors, racking in or out) means that even if the door is closed requires that elevated PPE be used.


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PostPosted: Tue Jun 26, 2012 10:04 am 
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Is 70E written for the general public or for skilled professionals? If the later, then the terms "doors open or closed, racked in or racked out" mean something that the general public might not get. The reference is to draw out switchgear breakers. It is not a reference to every possible electric components. What electric components do you know that 'don't' change energy states?

Normal operation includes more than just overcurrent protection. It also includes a means of disconnect. MCC buckets have big handles on them so you can disconnect the load without having to open the door. If the MCC's are 'maintained in good working condition' no PPE would be required to operate the handle with a closed door.

Operating or racking switchgear breakers, door open OR closed, require full PPE.

I believe that this is because of the persumed energy levels and risks being greater at the switchgear. I am not saying that this is true, but a guess as to what the code writers were thinking. We have to remember that the code writers are making mistakes. They misinterpretted what IEEE meant by 'nominal systems below 240' (which meant 208V and below) to make it 240V and below. Now we are changing from 125KVA transformers to 30KVA for the 'no analysis' threshold.

The original question deal specifically to what the code was saying. It clearly states that "normal operation" of "enclosed" electrical equipment si not likely to expose the worker to an electrical hazard if the electrical equipment has been properly installed and maintained by a qualified person. That means no PPE. Why would they make that statement if it didn't have meaning? They go on to then say that in most cases "closed doors do not provide enough protection to eliminate the need for PPE if the state of the equipment is know to readily change (i.e. doors open or close, breackers are racked in or out. You can't have both statements correct simultaneously unless the later has a threshold point at which the former doesn't apply. That threshold, based upon the language used - is drawout switchgear.

You can't pick and choose what text you want to reference, you have to reference the entirety and what is being said. The above is what I read.



that equipment maintained may have normal operations without PPE


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PostPosted: Tue Jun 26, 2012 10:05 am 
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Is 70E written for the general public or for skilled professionals? If the later, then the terms "doors open or closed, racked in or racked out" mean something that the general public might not get. The reference is to draw out switchgear breakers. It is not a reference to every possible electric components. What electric components do you know that 'don't' change energy states?

Normal operation includes more than just overcurrent protection. It also includes a means of disconnect. MCC buckets have big handles on them so you can disconnect the load without having to open the door. If the MCC's are 'maintained in good working condition' no PPE would be required to operate the handle with a closed door.

Operating or racking switchgear breakers, door open OR closed, require full PPE.

I believe that this is because of the persumed energy levels and risks being greater at the switchgear. I am not saying that this is true, but a guess as to what the code writers were thinking. We have to remember that the code writers are making mistakes. They misinterpretted what IEEE meant by 'nominal systems below 240' (which meant 208V and below) to make it 240V and below. Now we are changing from 125KVA transformers to 30KVA for the 'no analysis' threshold.

The original question dealt specifically to what the code was saying. It clearly states that "normal operation" of "enclosed" electrical equipment si not likely to expose the worker to an electrical hazard if the electrical equipment has been properly installed and maintained by a qualified person. That means no PPE. Why would they make that statement if it didn't have meaning? They go on to then say that in most cases "closed doors do not provide enough protection to eliminate the need for PPE if the state of the equipment is know to readily change (i.e. doors open or close, breackers are racked in or out. You can't have both statements correct simultaneously unless the later has a threshold point at which the former doesn't apply. That threshold, based upon the language used - is drawout switchgear.

You can't pick and choose what text you want to reference, you have to reference the entirety and what is being said. The above is what I read.


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PostPosted: Tue Jun 26, 2012 11:06 am 
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haze10 wrote:
Is 70E written for the general public or for skilled professionals? If the later, then the terms "doors open or closed, racked in or racked out" mean something that the general public might not get. The reference is to draw out switchgear breakers. It is not a reference to every possible electric components. What electric components do you know that 'don't' change energy states?

Normal operation includes more than just overcurrent protection. It also includes a means of disconnect. MCC buckets have big handles on them so you can disconnect the load without having to open the door. If the MCC's are 'maintained in good working condition' no PPE would be required to operate the handle with a closed door.

Operating or racking switchgear breakers, door open OR closed, require full PPE.

I believe that this is because of the persumed energy levels and risks being greater at the switchgear. I am not saying that this is true, but a guess as to what the code writers were thinking. We have to remember that the code writers are making mistakes. They misinterpretted what IEEE meant by 'nominal systems below 240' (which meant 208V and below) to make it 240V and below. Now we are changing from 125KVA transformers to 30KVA for the 'no analysis' threshold.

The original question deal specifically to what the code was saying. It clearly states that "normal operation" of "enclosed" electrical equipment si not likely to expose the worker to an electrical hazard if the electrical equipment has been properly installed and maintained by a qualified person. That means no PPE. Why would they make that statement if it didn't have meaning? They go on to then say that in most cases "closed doors do not provide enough protection to eliminate the need for PPE if the state of the equipment is know to readily change (i.e. doors open or close, breackers are racked in or out. You can't have both statements correct simultaneously unless the later has a threshold point at which the former doesn't apply. That threshold, based upon the language used - is drawout switchgear.

You can't pick and choose what text you want to reference, you have to reference the entirety and what is being said. The above is what I read.


It's wiggle room or weasel words, whichever way you wish to interpret it.

Lets say that the unthinkable - 1 in a 1,000,000,000 - happens and there is a full bus fault as the result of operating the breaker handle or even just pressing the ON/OFF button on the door. (Switchegar, MCC, whatever...) The fault is unrelated to the breaker operation and due to poor coordination the magnitude of the fault is over the withsdtan rating of the gear. Door blows off, injures or kills the worker.

Whose liability is this now? Not the manufacturers, but the Owners. Records of proper maintenance is looked at, effectiveness of the maintenance is looked at, the coordination is looked at. It WILL BE - 95% of the cases - the Owners fault and they simply can no longer rely on buying the right equipment, doing proper maintenance and coordination.


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PostPosted: Tue Jun 26, 2012 5:25 pm 
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LaszloZW wrote:
We have asked the MANUFACTURER of arc-resistant MV-gear: Please state in writing what credit can we take for arc-resistant gear? The asnwer was, in short: none.


Not quite the right way to interpret it. Read the ANSI arc resistant test standard. It is very clear what the test is. They hang 4 oz. cloth samples a specified number of inches away from all openings and check for damage after setting off a worst case arc flash in the gear.

This is just like looking at arc flash blankets. You can't use IEEE 1584 to analyze this because that was designed for a totally different test condition.

Second, H/RC "credits" are really bad policy in 70E. What is the incident energy reduction when going from H/RC 1 to 0? What about 2 to 1? How about 4 to 3? Notice a problem? The fact is though that in many cases in the tables, the hazard (incident energy) is NOT being reduced and thus the PPE should not be reduced. Either the likelihood is low enough that PPE is unnecessary, or not. In the case of arc resistant gear though this is true...the hazard is reduced to the point where PPE is no longer required except that regardless, nonflammable clothing (H/RC 0) should be worn because it is pathetically easy to get some materials (rayon, nylon) to melt.


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PostPosted: Tue Jun 26, 2012 5:34 pm 
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Quote:
Whose liability is this now? Not the manufacturers, but the Owners. Records of proper maintenance is looked at, effectiveness of the maintenance is looked at, the coordination is looked at. It WILL BE - 95% of the cases - the Owners fault and they simply can no longer rely on buying the right equipment, doing proper maintenance and coordination.


As you well know working for BASF (I've worked for them too), they use PHA analysis to look at chemical process equipment hazards to determine what is a tolerable risk. Electrical equipment is no different. In fact, ALL equipment is no different. Otherwise, better start putting up the meteor shields and Patriot missile defense systems just on the off chance that you get a SCUD missile strike or an errant meteor. I'm not even joking here. These two scenarios were actually used in an actual PHA at a BASF site in Georgia as "credible" threats by the safety manager when considering chemical mixing incidents.

EPA uses 1 in 10^6 cutoff. Virtually all industry standards use 10^4 or 10^5 cutoff for multiple fatality scenarios. That is the built in cutoff in IEC 61508 as well as the RIA standard. I believe nuclear uses 10^6 for a lot of cases.


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PostPosted: Tue Jun 26, 2012 5:47 pm 

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As a young budding engineer working as an electrican helper 52 years ago,I was shown what could have been a very nasty accident scene where a 4160 volt 3-phase, 1000 Ampere0on-load break switch poured its guts out the front. I was asked, "Do you now understand why you use your left hand and always stand to the side of any switch you operate?"

Normal operation is not to stand in front of the panel, switch circut breaker, and any electrical equipment when operating it or to even look at it when operating it. Thus PPE is not required.

Racking in circuit breakers is not a normal operation, you are basically changig the equiment configuation. I saw arcs and sparks when a PT drawer was rolled in.

The life you save is your own.


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PostPosted: Thu Aug 09, 2012 3:30 pm 

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JayWes38 wrote:
As a young budding engineer working as an electrican helper 52 years ago,I was shown what could have been a very nasty accident scene where a 4160 volt 3-phase, 1000 Ampere0on-load break switch poured its guts out the front. I was asked, "Do you now understand w
RECS wrote:
Informational Note No. 2 of 130.7 (a) establishes:

Statement: that "normal operation" of "enclosed" electrical equipment si not likely to expose the worker to an electrical hazard if:

Condition: The electrical equipment has been properly installed and maintained by a qualified person.

Lets assume the condition is satisfied. That is, the equipment has been installed and maintained properly.

Question 1: What is normal operation? Is it for example, opening or closing the main circuit breaker (i.e 4,000 A circuit breaker) from a service panel (as defined in the NEC) a normal operation? If it is, NFPA 70E Informational Note No. 2 from 130.7 (A) considers this interaction as one that will be as not likely to expose the worker to an electrical hazard and therefore should not wear PPE.

Informational Note No. 2 of 130.7(C)(15) establishes:

Statement: that in most cases "closed doors do not provide enough protection to eliminate the need for PPE if:
Condition: the state of the equipment is know to readily change (i.e. doors open or close, breackers are racked in or out.

Lets assume that the condition is satisfied. That is, we know that there is a lot of activity in the electrical equipment, we know that people are constantly opening and closing doors and frequently racking breakers in and out.

Question 2: When we approach this equipment with the doors closed to interact with it (i.e. operate the main circuit breaker, obviously without exposing any energized component by opening doors or taking covers off), then we would need to wear PPE?

Question 3: If racking breakers in and out is a normal operation and is done with the equipment enclosed on a panel that has been maintained and installed properly and that we know that its states readily changes, then which of the two informational notes takes precedence, do we need or do not need PPE?


hy you use your left hand and always stand to the side of any switch you operate?"

Normal operation is not to stand in front of the panel, switch circut breaker, and any electrical equipment when operating it or to even look at it when operating it. Thus PPE is not required.

Racking in circuit breakers is not a normal operation, you are basically changig the equiment configuation. I saw arcs and sparks when a PT drawer was rolled in.

The life you save is your own.


If you check the 'Report on Proposals' and the 'Report on Comments' you will see what the original intent was of the submitter (SQD - I believe) for this change. The original intent was to state very clearly that operating a disconnect or circuit breaker was in fact considered 'normal operation'. The committee approved this proposal 'in principle' but did not adopt his exact wording. They want the end user to be responsible for making the determination (risk assessment) for PPE necessity. It is interesting that they agreed in principle (I believe 24 out of 26 committee members).


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PostPosted: Fri Aug 10, 2012 7:16 am 
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Part of "normal operation" has to do with the status of the circuit.
If the reason for the device being open is known (e.g. LOTO for a mechanical belt change) then you would be closing onto a 'normal' circuit (i.e. little to no possibility of closing onto a fault). However if the device is going to be closed onto an unknown circuit (e.g. wiring has been changed) then you would might consider this a 'non-normal' operation (i.e. their is a possibility of closing onto a fault).

A 4000A breaker, tested to UL489, has been subjected to many 0-100% FLA operations, however it has only been tested to a handful of low level fault, and only 2 full AIC faults. Resetting a breaker, like this, after it has tripped on a short circuit , should probably not be considered a "normal operation".


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PostPosted: Thu Aug 16, 2012 3:12 am 
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I agree with JBD. Opening a device to perform LOTO for mechanical maintenance etc is normal. Recovering from a fault or overload is an "abnormal" condition. Racking breakers/MCC Buckets/Bus Plugs into an energized bus is considered "repair" and an energized work permit must be used.


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