Been away Available Arc Fault current and stickers?

[ShockedMonkey]

Hi everyone,

I'm an EC and have been out of the industry long enough that I've had to re-learn the entire code. I'm a little guy, starting up in a new location, service work and possibly some residential. Previously, did schools, light industrial, and some commercial.

My question is what is the easiest way to calc switch-gear Available Arc Fault current and cheapest way of labeling it? (110.16, 110.24)

I downloaded the forum calc-spreadsheet and if that works best that's fine. I'm assuming software is cost prohibitive at this point.

Thanks

 

[hmspe]

I use the method in the Bussmann SPD. http://www.cooperindustries.com/con...ry/selecting_protective_devices_handbook.html

 

[wbdvt]

I think it depends on what you are asking: Are you asking how to calculate the arcing fault current and the subsequent incident energy value or are you asking how to calculate the bolted fault current and associate clearing time to be able to use the table in NFPA 70E-2015?

 

[Sunny_92]

In order to meet the requirements of 110.24(A), my suggestion would be:

1. Contact the utility company to obtain the fault data from them. (In my experience they usually give available fault current and X/R at the XFMR secondary terminals for low voltage services)

2. Use the Eaton Bussman Fault Current Calculator app (free, and available for Apple & Android) to calculate the fault current at the service equipment. The app will let you input the available fault current from the utility and the service conductor data in order to calculate the fault current at the end of the conductors.

When it comes to printing the labels, I'm not sure what your cheapest option will be. We own a DuraLabel Pro 300 and print all of our own labels.

In order to meeting the requirements for 110.16 for arc flash labeling, I would suggest hiring an outside engineering firm to complete the arc flash study.

 

[NewtonLaw]

Arc-Fault Current?

Arc-Fault Current?

Hi everyone,

I'm an EC and have been out of the industry long enough that I've had to re-learn the entire code. I'm a little guy, starting up in a new location, service work and possibly some residential. Previously, did schools, light industrial, and some commercial.

My question is what is the easiest way to calc switch-gear Available Arc Fault current and cheapest way of labeling it? (110.16, 110.24)

I downloaded the forum calc-spreadsheet and if that works best that's fine. I'm assuming software is cost prohibitive at this point.

Thanks

Hello,

Are you asking to calculate fault current or Arc-Flash energy. I am a little confused by the term Arc-Fault since it suggests a possible open Arc during the fault. If it is just fault current the Bussman (Eaton) fault calculator is a great tool. If it is Arc-Flash energy, not so much.

 

[wbdvt]

In order to meet the requirements of 110.24(A), my suggestion would be:

1. Contact the utility company to obtain the fault data from them. (In my experience they usually give available fault current and X/R at the XFMR secondary terminals for low voltage services)

2. Use the Eaton Bussman Fault Current Calculator app (free, and available for Apple & Android) to calculate the fault current at the service equipment. The app will let you input the available fault current from the utility and the service conductor data in order to calculate the fault current at the end of the conductors.

When it comes to printing the labels, I'm not sure what your cheapest option will be. We own a DuraLabel Pro 300 and print all of our own labels.

In order to meeting the requirements for 110.16 for arc flash labeling, I would suggest hiring an outside engineering firm to complete the arc flash study.

This will only give you the bolted fault current at the transformer terminals. If you want to use the tables in NFPA 70E, you need to determine the bolted fault current and clearing time at the piece of equipment you are working on. This will determine if you are within the parameters of the tables. To do that you have to model the system to the piece of equipment using the impedance of all the conductors to that equipment to determine the fault current. Once that is obtained then you need to determine the clearing time by utilizing the time current curve for the upstream protective device. So for example if you working on a 480V panelboard the NFPA 70E table says that is Cat 2 PPE as long as the bolted fault current at that panelboard is less than 25kA with a max clearing time of 2 cycles (0.03 sec). So if you have 10kA of fault current at that panelboard but the upstream trip device clears that fault current at 5 cycles, you cannot use the table method to determine the PPE.

 

[ShockedMonkey]

Thank you for the replies and the app, that is helpful. I should have phrased it as two separate questions, as I was inquiring about both.

Thank you wbdvt, and yes that was what I was wondering. I didn't notice there are example calcs in Annex D of NFPA70 to figure it out.


I'm kind of frustrated with this as a sparky if the AHJ wants this done for any tie-ins to existing gear; is this typically the case now or just with new service installs?


I realize the intent is to save lives and mitigate injury, but having to calculate rather than set a large range. Then again this is coming from someone who used to hot tap or drill live 480 gear with leather gloves, so I was a lucky idiot; however I realized the consequences.

If I have to hire an EE each service call, software is looking much cheaper.

Thanks

 

[Sunny_92]

Misunderstood post, please delete.

 

[wbdvt]

If I have to hire an EE each service call, software is looking much cheaper.

Thanks

NFPA 70E-2015 Art. 130.5 (D) states: The owner of the electrical equipment shall be responsible for the documentation, installation, and maintenance of the field marked label.
The field marked label is the arc flash label described in that article.

Additionally, as a contractor hired by a company, the company is considered a host employer and is responsible for informing you of the applicable site hazards so that you can protect yourself with the proper PPE.

 

[iwire]

NFPA 70E-2015 Art. 130.5 (D) states: The owner of the electrical equipment shall be responsible for the documentation, installation, and maintenance of the field marked label.
The field marked label is the arc flash label described in that article.

Additionally, as a contractor hired by a company, the company is considered a host employer and is responsible for informing you of the applicable site hazards so that you can protect yourself with the proper PPE.

The reality is in most cases if an EC tries to go that route the customer is going elsewhere.

Things are getting better but still a long way to go.

 

[NewtonLaw]

[Partial QUOTE=ShockedMonkey;1796769] ...............

I realize the intent is to save lives and mitigate injury, but having to calculate rather than set a large range. ..............

Thanks[/Partial QUOTE]

You may find the estimating method is good enough and the better alternative. What would it cost you or your customer to do via this method versus a full study?

The major cost for an Arc-Flash analysis is the data collection which means Utility Fault Duty, equipment details such as size, type, TCCs, lengths, Bus sections, fuse specs, creating one-lines and labels along with the appropriate training. You may find some EEs will do the Arc-Flash analysis for where you collect all the necessary data, create a hand drawn one-line and apply identification names and later the labels may be your responsibility or the firm that performs the Arc-Flash analysis. Depends on what level of detail, new equipment versus older equipment, etc.

Shop around, you may be surprised.

Hope this helps,

Newton Law

 

[GoldDigger]

NewtonLaw:
You cannot make that kind of edit to forum tags and expect it to do anything useful.
Using ellipses (rows of dots) before and after) conveys the needed information if you feel it is important.

Sent from my XT1585 using Tapatalk

 

[wbdvt]

The other consideration in deciding to use the tables versus an actual study is that you have approximately 50% chance of getting the PPE right. This was one of the conclusions in an IEEE paper, Field Analysis of Arc Flash Incidents and the Related PPE Protective Performance, Paper # ESW2009-15. This paper utilized data from DuPont. For instance one example of this was that the table method listed the work as requiring Category 1 PPE (min rating of 4 cal/cm2). There was an accident and the individual received 3rd degree burns to the face, arms and torso. As part of the accident investigation the actual incident energy was calculated to be 26 cal/cm2 which would be Cat 4 PPE.

 

[ShockedMonkey]

I apologize for my ignorance, it's been 13+ years I've been away from the code/Electrical contracting.

I should have phrased the question: How are EC's handling these two code requirements, if requested by the AHJ, doing service work?


I want my work to comply, in the most efficient and least expensive way possible.

Thank you.

 

[NewtonLaw]

?

?

NewtonLaw:
You cannot make that kind of edit to forum tags and expect it to do anything useful.
Using ellipses (rows of dots) before and after) conveys the needed information if you feel it is important.

Sent from my XT1585 using Tapatalk

Sorry I guess. Not sure what I did that was incorrect? I was trying to shorten the total quote such that my response was specific to one question or comment. Not allowed?

 

[dkidd]

I apologize for my ignorance, it's been 13+ years I've been away from the code/Electrical contracting.

I should have phrased the question: How are EC's handling these two code requirements, if requested by the AHJ, doing service work?


I want my work to comply, in the most efficient and least expensive way possible.

Thank you.

You can comply with 110.16 with the generic sort of label that manufacturers provide that don't give any values or require calculations, just a warning. Refer to the Exhibit in the NEC Handbook.

You need the value for the available fault current from the utility to prepare a label with the value to comply with 110.24. Unless the installation would reduce that number at the service, I would use it to be conservative. It is only required at the service.

 

[dkidd]

Sorry I guess. Not sure what I did that was incorrect? I was trying to shorten the total quote such that my response was specific to one question or comment. Not allowed?

Your method didn't work. It is allowed (although you shouldn't change the intent of the post).

 

[kwired]

You can comply with 110.16 with the generic sort of label that manufacturers provide that don't give any values or require calculations, just a warning. Refer to the Exhibit in the NEC Handbook.

All it asks for in 2014 NEC (not sure what 2017 says yet) is a warning marking, nothing about incident energy levels is mentioned. A lot of equipment used already has manufacturer markings already on it that meet this requirement. I have on occasion marked equipment with a field made label that simply says "Warning: Potential arc flash hazard" when I felt there was no other compliant marking. Never have had a comment from an inspector yet (good or bad).

 

[dkidd]

All it asks for in 2014 NEC (not sure what 2017 says yet) is a warning marking, nothing about incident energy levels is mentioned. A lot of equipment used already has manufacturer markings already on it that meet this requirement. I have on occasion marked equipment with a field made label that simply says "Warning: Potential arc flash hazard" when I felt there was no other compliant marking. Never have had a comment from an inspector yet (good or bad).

That's what I said. :huh:

 

[ShockedMonkey]

You can comply with 110.16 with the generic sort of label that manufacturers provide that don't give any values or require calculations, just a warning. Refer to the Exhibit in the NEC Handbook.

You need the value for the available fault current from the utility to prepare a label with the value to comply with 110.24. Unless the installation would reduce that number at the service, I would use it to be conservative. It is only required at the service.

Thanks!