Building Arc-flash studies

[MIEngineer]

For those that interact with commercial buildings, how are the managers incorporating arc-flash studies into personnel safety? We have multiple buildings and due to the cost of an arc-flash study cannot do them all at once. Has anyone seen buildings that have perfromed the arc-flash study, with the descriptive labels on the front of all the panels?

I see a few options on how to proceed:

a) Ignore and continue business as usual and pray no one gets injured.
b) Follow the PPE recommendations from articles 130 of NFPA 70E. Though without performing the full study we don't know if we are within the boundaries for clearing times.
c) Require personnel to don PPE for a level higher than what we think will be encontered in the building (AKA Overkill, no pun intended).

These buildings have every flavor of services the highest being 480V up to 2000A.

I am wondering what others have encountered since the arc-flash requirements are much less straightforward than just short circuit protection.

Thank you all for the input.

 

[zog]

Yes, I would guess somewhere around 20-50% of industrial/commercial plants have the required labels, the bigger the company the more likely that is, depends on where you live, if you are in Michigan as i am guessing is on the higher end of that.

Responses to your options
a) Good luck with that, be ready to get fined in the next couple of years and end up having to do it anyways.
b)You dont need to do an arc flash study to use the tables, just fault current calcs and clearing times, thats far from a full study. If you dont meet the clearing time requirements to use the tabels that is a easy fix by doing some retrofits to a few of your breakers or a simple single engineering solution at your service entrance.
c)not a good idea, you dont know what is required so how can you require more protection than what you dont knw, thats impossible.

All flavors is hardly included in "all the way up to 480V, 2000A" thats a very small system in my world. I suggest you look at IEEE 1584 for guidance on where you need to do the analysis, that will eliminate most of the panels at a facillity your size.

It sounds to me like you have either not dug in deep enough to the requirements or have hired a contractor to quote you the study who either hasnt a clue or is trying to get you to do a full analysis, if you are located where I think you are located I can guess the answer to that.

You need generic labels on all panels as described in 110.16 of the NEC but the 2009 NFPA 70E will require more info on the labels so you might as well go that route, at least the PPE required or Ei available.

 

[MIEngineer]

You are correct in assuming I have a lot to learn in terms of the arc flash labeling requirements. Please elaborate on the differences. In the meantime I will obtain IEEE 1584.

I thought to determine the incident energy at a given panel required:
1) The available short circuit at the service entrance
2) the breaker or fuse type, model #, etc.
3) the conductor distances
4) any transformers, disconnects, basically an up-to-date one-line of the facility.
Is this not a full study?

I don't understand how the requirements of 70E can be applied without this information. "Do nothing" was never a viable option but as one without the purse strings it's something that needs addressing.

Thank you for the advice.

 

[zog]

I really dont think it is possible to teach someone how to do arc flash studies in a forum like this.

Either go get some training or hire someone to do it for you.

Basically the 1584 will tell you an arc is not self sustaining on less than 240V systems fed by a tranasformer les than 125kVA, so that most likely takes care of most of your system.

To use the tables you must verifiy that you are within the limitations of the tables, if you dont have any one lines for your buildings you may need a S/C and PDC study done on some points to verify the tables can be used.

Or, you can do a full study, which is best but it sounds like your company is having a little sticker shock at the cost of doing one, there are ways to help that also, mostly have your own electricians do the data collection and provide the info to the engineering firm doing the study.

 

[Bombo]

Panel Labels

Panel Labels

You need generic labels on all panels as described in 110.16 of the NEC but the 2009 NFPA 70E will require more info on the labels so you might as well go that route, at least the PPE required or Ei available.

Hey Zog, I am an EE intern working at a large production company. I am tasked with figuring out where we should put IR viewing panes on the Switchgear and MCC's. An arc flash study was completed prior to my arrival, and labels have been affixed which list PPE category, voltage, boundary limits, name of bus and protective device for that bus.

As I began looking at the equipment I found that the labels are all placed differently. On one SG the label for the line side of the main breaker might be right on the breaker panel and on an identical SG (with same ratings) the label might be on the transition panel (from transformer to breaker)??? This is confusing. After talking with a senior electrician, now a trainer, he agrees with me that we should have a label on EVERY panel that could be removed. I don't think overkill here is bad. Does this seem excessive to anyone??

 

[zog]

It just needs to be clearly visible to the person that will work on that equipment. The arc flash level is the same for the main breaker as it is for the transition so eaither place is fine, putting it on the main breaker door makes more sense because that what will get operated, rare that the transition section cover is removed (Should never be removed whhile energized).

AS far as the IR viewing windows, those are overrated, you will never get 100% coverage and you can install a continous IR monitoring system (I.E. Exertherm) for less $$.

 

[Bombo]

Panel labels / IR windows

Panel labels / IR windows

AS far as the IR viewing windows, those are overrated, you will never get 100% coverage and you can install a continous IR monitoring system (I.E. Exertherm) for less $$.

Thanks a lot,

I was a little concerned about the amount of coverage we'd get with the windows, especially if they are put in the MCC's.

I've seen the adds for the continuous monitoring devices, have they been around long enough to be trusted? What connections would you put them on, typically? Do you know of anyone using this system?

 

[zog]

Thanks a lot,

I was a little concerned about the amount of coverage we'd get with the windows, especially if they are put in the MCC's.

I've seen the adds for the continuous monitoring devices, have they been around long enough to be trusted? What connections would you put them on, typically? Do you know of anyone using this system?

They are pretty new to the US but very common and have been used for a long time in the UK. I have installed a few of these systems and they worked just fine.

 

[jim dungar]

After talking with a senior electrician, now a trainer, he agrees with me that we should have a label on EVERY panel that could be removed. I don't think overkill here is bad. Does this seem excessive to anyone??

Many people go with the idea that every "last/final" deadfront panel that can be removed thus exposing live parts should have a label advising a hazard exists (this is the label required in NEC 110.16). This label alerts the person to find the label that provides the PPE information. The PPE information label location is defined in the company's ESWP program, but it is usually on the lugs or the main device compartment right next to the equipment primary name tag/label.

Other companies put a PPE label on every hinged door (both the front and rear of switchgear, and each MCC vertical section).

Personally I feel that the more "warning" labels there are the more likely they are to be "lost in the clutter". Many manufacturers now include arc flash and shock warning labels so adding additional labels can cause confusion. Labels large enough to contain boundaries and PPE can overwhelm small equipment and small deadfront spaces. I see no reason to put labels on the outside of panelboards that have the dead front mounting screws behind the panel door.

 

[Bombo]

They are pretty new to the US but very common and have been used for a long time in the UK. I have installed a few of these systems and they worked just fine.

Thanks again, will definitely look into this more.

 

[Bombo]

Personally I feel that the more "warning" labels there are the more likely they are to be "lost in the clutter". Many manufacturers now include arc flash and shock warning labels so adding additional labels can cause confusion. Labels large enough to contain boundaries and PPE can overwhelm small equipment and small deadfront spaces. I see no reason to put labels on the outside of panelboards that have the dead front mounting screws behind the panel door.

Excellent points Jim! I can certainly see your point on losing them in the clutter of other labels, tags, etc...

I guess it just comes down to us finding our own uniformity to take away confusion and train properly the people who will be maintaining this equipment.

 

[jim dungar]

I guess it just comes down to us finding our own uniformity to take away confusion and train properly the people who will be maintaining this equipment.

It is your Electrical Safe Work Practices program. Jus like a hazardous material program, one size "fits none".

 

[jbt260]

I agree. Too many labels can muddy the waters

Manufacturer's should not provide arc flash hazard labels on equipment. This should be done after the equipment is installed and a short circuit/arc flash study has been completed based on as-built conditions.

 

[zog]

I agree. Too many labels can muddy the waters

Manufacturer's should not provide arc flash hazard labels on equipment. This should be done after the equipment is installed and a short circuit/arc flash study has been completed based on as-built conditions.

They provide the generic labels required by 110.16

 

[jim dungar]

Manufacturer's should not provide arc flash hazard labels on equipment.

Manufacturers have been applying "danger of electrical shock" labels for decades, now they have simply added the words "and arc flash". In today's litigious society I doubt that any manufacturer's lawyers would advise them against including warnings on their equipment.