ARC FLASH LABELING

[j rae]

How do I determin the arc flash rating label to put on panels,switch gear, motor starters???

 

[zog]

Determine the available fault current for each point in your system, then determine the clearing time of the OCPD that protects that point, then calculate the incident energy at the working distance (determined by equipment), then run every senario possible (different configurations, sources, lowest and highest possible arcing current at a minimum).

Or hire someone that does this for a living

 

[BPoindexter]

While Zog's suggestion is clearly the superrior one you can use the tables in NFPA 70E 130.7 to determine Hazard Category in lieu of an incident energy study. You have to be careful though as there may be areas with low impedance transformers, etc that give you a higher normal than fault current/energy. Best to have a study as it can also possibly eliminate unnecessarily bulky PPE.

 

[wbdvt]

While Zog's suggestion is clearly the superrior one you can use the tables in NFPA 70E 130.7 to determine Hazard Category in lieu of an incident energy study. You have to be careful though as there may be areas with low impedance transformers, etc that give you a higher normal than fault current/energy. Best to have a study as it can also possibly eliminate unnecessarily bulky PPE.

If using the tables in NFPA 70E 130.7, be aware of the parameters that must be met, particularly the maximum short circuit current available and the maximum fault clearing time.

The best thing to do is to hire someone to do the study. Having a study done has many benefits:

• determines actual incident energy
• determines what PPE is needed which in many cases can be less than if one went by the tables in NFPA 70E 130.7
• identifies any underduty equipment
• coordination study can be done at the same time as the arc flash analysis leading to a more reliable electric system

 

[jim dungar]

The best thing to do is to hire someone to do the study. Having a study done has many benefits:

Don't forget, timeliness.

Professionals will start and complete the project (including installed labels) in a reasonable amount of time.
Yes there are always exceptions, but their full time job is the study, they are not distracted by a machine going down, someone being on vacation, or the antipathy of doing a project with no apparent benefit.

 

[petersonra]

one of our customers sent two of their electricians to some kind of school and bought some software to calculate short circuit currents and incident energy. They have now spent better than 2 years in the plant on this project, and it is now expected it will never be completed as they are planning to go back and look at everything every 5 years even if it is not changed and it is expected that the amount of effort that will generate will keep them bust indefinitely.

my understanding is they have labeled about 1/3 of the stuff in the plant they plan to label.

 

[jim dungar]

... expected that the amount of effort that will generate will keep them bust indefinitely.

my understanding is they have labeled about 1/3 of the stuff in the plant they plan to label.

A good company can come in collect data, creat a report , and install labels for 1000+ locations, start to finish including job take off, quotation, review meetings, and indecisions in less than 6 months.

There is absolutely no reason to evaluate things that have not changed. After all, if the equipment has not physically changed, the model is still valid.
Keep the model up to date and relable the locations that have changed since last time.

 

[petersonra]

A good company can come in collect data, creat a report , and install labels for 1000+ locations, start to finish including job take off, quotation, review meetings, and indecisions in less than 6 months.

There is absolutely no reason to evaluate things that have not changed. After all, if the equipment has not physically changed, the model is still valid.
Keep the model up to date and relable the locations that have changed since last time.

when I heard that two electricians were basically assigned indefinitely to this task it seemed a little crazy to me too.

in fairness, the place is in a state of flux with almost continuous change going on, and it is has been that way for as long as I can remember (> 20 years).

 

[wbdvt]

I have been involved with a project that was started 3 years ago for an arc flash hazard analysis. The company did not want to spend the $10k to have my company do the data collection. They wanted their in-house electricians to do it. Guess what the priority was! We are now being asked to re-quote the project to do the data collection.

An outside firm can easily do the data collection, analysis and labeling in a 6 month period even for something with 1000 buses.