Arc Fault Hazard Lower Limit

[Bompa]

Arc Fault Lower Limit?

This question concerns whether there is a practical lower limit below which the energy available makes Arc Flash Labeling unnecessary.

I know there is an exclusion for ?dwelling units?, but does every other piece of electrical equipment that possibly would be checked while energized require labeling? If it does, does it follow that a person opening the case of such a labeled piece of equipment need to have the certified training, the safety suit, etc. that has come to be associated with the ?Arc Flash Hazard? warning label?

Surely, there must be a point below which the labeling is not required. If not, we are going to see such labels on everything and the real meaning will be lost. Neither the code language nor the NEC Handbook seem to address this.

 

[jim dungar]

If you are working on energized equipment, you must no which hazards exist so that you can use the appropriate PPE.

If you see a device without any labeling, how are you going to know what hazards are present?

 

[Bompa]

So, in the future, I am going to see this warning label on my toaster, table lamp and electric shaver?

" ! WARNING - ARC FLASH HAZARD - Appropriate personal protection equipment required. "

On something I am reviewing that very label is being called for. Are we reaching a point of being ridiculous and where the unintended consequences are that everyone will have to have Arc Flash Hazard training certification to buy a voltmeter?

 

[jim dungar]

So, in the future, I am going to see this warning label on my toaster, table lamp and electric shaver+

What interaction 'in a manner that may cause and arc fault' are you doing with these appliances?
The proper application of NFPA70E and OSHA's 'general duty clause' provides for an assessment (i.e. possibility of occurrence) of risk.

 

[don_resqcapt19]

So, in the future, I am going to see this warning label on my toaster, table lamp and electric shaver?

" ! WARNING - ARC FLASH HAZARD - Appropriate personal protection equipment required. "

...

Very likely, give how we do things here in the US...it is never our fault and we have to be warned about every possible negative outcome.:happysad:

 

[Strife]

If you see a device without any labeling, how are you going to know what hazards are present?

Like chain saws carrying the labeL:"WARNING, moving chain could sever your fingers?"
Some time ago I heard someone claiming ONLY in US you will see that kind of label. Most other countries, people won't admit they were THAT STUPID.

Or maybe, like the Credit Cards label?:"WARNING, USING THIS CARD CAN GET YOU IN DEBT"??????????

Or even better, here's a new label I propose:"WARNING, eating 10 big mac a day will make you FAT"

 

[Bompa]

What interaction 'in a manner that may cause and arc fault' are you doing with these appliances?
The proper application of NFPA70E and OSHA's 'general duty clause' provides for an assessment (i.e. possibility of occurrence) of risk.

I guess that now we are getting around to the point of my question, Jim. As a designer (in this case I am a reviewer) on what basis do I make a judgement that the particular thing I am installing is likely to constitute an arc fault risk?

Virtually every assembly in this particular design package called for a Brady Label #81104, which is a 2x3 stick on label with the warning words I quoted earlier. Obviously, it is intended to get around violating NEC 110.16, but does it serve any useful purpose? Does it help you to know what type of PPE (if any) you must wear? I think not.

Since these particular components dealt with security wiring, let's just say they are the equivalent of an "ADT" home security panel except in an industrial environment. Power source is the equivalent of a plug-n-cord connection to a 20 amp convenience outlet. Interior components would include a small power supply, relays and such, end-of-line resistors, etc. The only people who would be allowed to open the cover would be highly trained security equipment professionals.

Let's just say I was surprised to see the labeling requirement. In my mind it serves no purpose. It could cause a safety specialist to require suiting up for arc fault hazards if the panel was to be worked on, which would be a costly negative effect.

I can't really say the designers were wrong in requiring the label, based on the code. But I think it is silly. I believe it is the equivalent of the story "The boy who cried wolf". What are your thoughts, Jim?

 

[don_resqcapt19]

...
Virtually every assembly in this particular design package called for a Brady Label #81104, which is a 2x3 stick on label with the warning words I quoted earlier. Obviously, it is intended to get around violating NEC 110.16, but does it serve any useful purpose? Does it help you to know what type of PPE (if any) you must wear? I think not. ...

No the rule in the NEC does not specify PPE and is not intended to.

Since these particular components dealt with security wiring, let's just say they are the equivalent of an "ADT" home security panel except in an industrial environment. Power source is the equivalent of a plug-n-cord connection to a 20 amp convenience outlet. Interior components would include a small power supply, relays and such, end-of-line resistors, etc. The only people who would be allowed to open the cover would be highly trained security equipment professionals.

I don't see that type of equipment as being covered by the rule in 110.16.

110.16 Arc-Flash Hazard Warning. Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that are in other than dwelling units, and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of
potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

...I can't really say the designers were wrong in requiring the label, based on the code. But I think it is silly. I believe it is the equivalent of the story "The boy who cried wolf". What are your thoughts, Jim?

I see the designers as being wrong if they are saying that the NEC requires the labels, of course as designers, they are free to exceed the code rules. I don't see any type of security equipment falling under 110.16.

 

[jim dungar]

I can't really say the designers were wrong in requiring the label, based on the code. But I think it is silly. I believe it is the equivalent of the story "The boy who cried wolf". What are your thoughts, Jim?

Lable: TURN OFF POWER BEFORE SERVICING.
No interaction with energized parts means no concern of arc flash.

But I am guessing the designers are more worried about liabilty lawsuits and not code compliance.

 

[Bompa]

No the rule in the NEC does not specify PPE and is not intended to.


I don't see that type of equipment as being covered by the rule in 110.16.


I see the designers as being wrong if they are saying that the NEC requires the labels, of course as designers, they are free to exceed the code rules. I don't see any type of security equipment falling under 110.16.

First of all, Don, thanks for the reply.

What I want to know is what would be the basis for telling them that they are wrong and that this type of equipment is not covered by the rule in 110.16? It is quite literally my job, as reviewer, to tell them where they are wrong or they have created a constructability problem.

Yes, they did say to install those labels as required by NEC 110.16. (Possibly not an exact quote as I am writing this from home and don't have access to the documents.)

I really don't see any language in the code that excludes this equipment, even though my gut tells me it doesn't apply. When I see that warning, I see people suited up as protection from a high energy fireball. Stuff fed from 120V, 20A branch circuits might kill someone by stopping their heart, but it doesn't produce high energy fireballs.

It would not be legitimate to post a sign requiring that it be serviced de-energized. I can well imagine that the security professionals work on this equipment energized all the time. I've not witnessed it, but I'd find it very hard to believe that they use any special PPE.

So, back to my original question --- Is there a lower energy limit below which Arc Flash Hazard warning signs are inappropriate? Is there some commonly accepted standard (however informal) that says branch circuits below a given amperage and voltage do not require warning signs?

 

[Bompa]

Lable: TURN OFF POWER BEFORE SERVICING.
No interaction with energized parts means no concern of arc flash.

But I am guessing the designers are more worried about liabilty lawsuits and not code compliance.

Jim,

I have sometimes used that very approach on certain panelboards. However, I don't feel it is at all practical in this case. I am certain that the service professionals have to be allowed to service it energized.

I do agree with your statement about liability but they definitely did state that it was to comply with NEC 110.16.

 

[jim dungar]

I do agree with your statement about liability but they definitely did state that it was to comply with NEC 110.16.

Compliance with 110.16 is extremely easy:
Warning: Danger of electric shock or arc flash. No user servicable parts.

What 'hazard' warnings are on your equipment now?

 

[don_resqcapt19]

First of all, Don, thanks for the reply.

What I want to know is what would be the basis for telling them that they are wrong and that this type of equipment is not covered by the rule in 110.16? It is quite literally my job, as reviewer, to tell them where they are wrong or they have created a constructibility problem. ...

I just do not see they type of equipment you are talking about falling under the wording of 110.16.

...Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers, ...

I don't see any way that security equipment is "such as" the equipment listed.

 

[tom baker]

to your original question
Arc Flash labeling is not required for dwelling units
NFPA 70E does not require PPE for 240 Volt systems fed from a 125 KVA transformer if I am reading 70E right.
But there is a difference between labeling and PPE.

 

[jim dungar]

NFPA 70E does not require PPE for 240 Volt systems fed from a 125 KVA transformer if I am reading 70E right.

Tom,
You are reading it wrong.

NFPA70E does not require calculations or a study for small systems.
The industry consensus seems to be to treat these automatically as HRC=0. This practice will probably have to be 'rethought' with the next version of 70E based on what happesn with IEEE 1584.

The use of PPE is always required.
Labelng is required to advise the worker of what PPE to use.

 

[Bompa]

Tom,
You are reading it wrong.

NFPA70E does not require calculations or a study for small systems.
The industry consensus seems to be to treat these automatically as HRC=0. This practice will probably have to be 'rethought' with the next version of 70E based on what happesn with IEEE 1584.

The use of PPE is always required.
Labelng is required to advise the worker of what PPE to use.

OK, Jim, now you have really gotten my interest with your statement: " The use of PPE is always required. "

I am not very well versed in NFPA 70E, but it looks to me like the very lowest level of PPE is leather gloves. (because the hands are the normally the closest thing to energized parts)

With your statement, are you saying that it is a violation of 70E to use a voltmeter without leather gloves? (By definition, if you are taking a voltmeter reading, you are working on energized equipment.)

 

[don_resqcapt19]

...With your statement, are you saying that it is a violation of 70E to use a voltmeter without leather gloves? (By definition, if you are taking a voltmeter reading, you are working on energized equipment.)

Actually, if the voltage is over 50 volts you need voltage rated gloves. You may need other PPE based on the arc flash/blast hazard.

 

[jim dungar]

OK, Jim, now you have really gotten my interest with your statement: " The use of PPE is always required. "

Remember there is no 'universal PPE'. PPE is not solely for arc flash nor voltage.
The actual PPE required depends on the task being performed and the hazards that exist.

 

[zog]

Actually, if the voltage is over 50 volts you need voltage rated gloves. You may need other PPE based on the arc flash/blast hazard.

Maybe, maybe not. That depends on the configuration of the equipment. V rated gloves are required inside the RAB which for 120V is "avoid contact", here is where some judgement is allowed for, if you have external test points for example where it would be near impossible to make contact with energized parts then V-rated gloves would not be required.

 

[don_resqcapt19]

Maybe, maybe not. That depends on the configuration of the equipment. V rated gloves are required inside the RAB which for 120V is "avoid contact", here is where some judgement is allowed for, if you have external test points for example where it would be near impossible to make contact with energized parts then V-rated gloves would not be required.

My understanding is that the "avoid contact" applies to both your body and any tools you may be using. If you are using a tool to contact the live parts, you need voltage rated gloves even if the tool is rated for the voltage. Table 130.7(C)(15)(a)