Arc Flash Study Components, Requirements

When was the last time you had an arc flash study conducted in your facility? An arc flash study is the assessment of a facility by an electrical safety professional to determine risks and hazards in relations to your electrical systems.

Learn about arc flash study from one of Eaton’s electrical experts and how ErieTec can help you.

What is Arc Flash Study?

Arc Flash Study is the requirement of NFPA 70E to choose the appropriate PPE in your facility. To determine this, we need a calculation of how much energy could be released during an arc flash. This ties into another standard.

Most of us are familiar with the 2002 version of the IEEE 1584, which was essentially the first standard where we had good test data. When they wrote that standard, they tested equipment, blew it up in labs and measured how much energy is released during an arc flash. From these measurements they were able to build the equations and calculate how much energy is being released, in any piece of equipment.

Something that they have to consider is what size the equipment is, from a capacity standpoint, what’s the voltage of the equipment and how big is the box. Or additionally, are we talking a switch board, a panel board and ground or ungrounded? Other questions are what is your system currently running in state wise? Are you running on utility power? Are you running on generator power? Do you have motors turned on right now that regenerate back into the current fault? Or are they all turned off? Those all will affect analysis and the software and engineering doing that study.

IEEE 1584 was then updated in 2018. What is important with that revision is they looked at bus orientation. Is your bus bar running vertical or horizontal. They found that makes an effect on the calculation for arc flash.

A lot of very significant details go into that arc flash analysis. The main purpose is to determine the worst-case energy that could be released. An arc flash study takes all those equations and all that test data into account.

From there, we will model your system and Eaton’s software will do the calculations to tell us how much energy is going to be released.

These equations can get very technical, so Eaton’s experts do not recommend trying to do them yourself. That is what our friends at Eaton are for!

What does the study consist of?

Typically, in an arc flash study, it coincides with short circuit analysis and a coordination study. The short circuit analysis would be how much fault current can be released in your system. This is based off the equipment you have and how much impedance and resistance the system has, but it is also based off how strong your utility is.

This specific Eaton location is outside of Pittsburgh, P.A., and their services are pretty powerful. They can get a lot of fault current from that utility. Although, if your facility is out in the middle of the country, far away from major cities, you’re not going to have that high level of fault current. So, fault current comes into effect. The short circuit analysis will confirm that your equipment can actually interrupt that fault.

It’s not the 25 amp or 50-amp breaker they are looking at during the short circuit analysis, that’s not the rating Eaton is looking at. They are looking at 10,000 amps interrupting rating on the breaker or on the device. A short circuit analysis is required in arc flash study to determine what all the fault values are going to be.

Beyond that, you have the coordination study. The coordination study includes all settings for your breakers, all the sizes of your fuses and other protective device and relays in your system. What they are looking for is to ensure that your downstream device is closest to the fault will interrupt that fault first.

For example, if I create a fault in an outlet in my living room, I only want my living room to go out. I don’t want my main breaker for the house to trip or I don’t want the utility fuse on the wall to end up blowing. I only want that small 20-amp receptacle circuit to trip offline. Essentially, that is what a coordination study does.

The study ensures that your closest downstream device trips first. This is important in an arc flash study because when we take the fault values from the short circuit and the timing from the coordination study, those are 2 primary factors that go into the arc flash analysis. Typically, you will see an arc flash study combined with short circuit coordination from that perspective.

How Often is an Arc Flash Study Required?

An arc flash study has to be reviewed every 5 years according to NFPA 70E. Every 5 years, you should be having an engineer look at that system, look at the analysis to ensure it is still an accurate calculation. If nothing changes in your facility, it might be as simple as let’s talk to the utility and make sure fault current values haven’t changed or just have a site visit to ensure that all of the calculations are valid. However, anytime there is a change in your system, a coordination and short circuit analysis is required.

NFPA 70E: Requires an arc flash assessment shall be performed to determine the risk, safety related work practices required, the arc flash boundary, the incident energy at the working distance and the PPE within the arc flash boundary shall use.

Hospitals are going to have additional requirements including selective coordination – aka perfect coordination. You have to have a coordination study that does that, as well as the arc flash analysis.

On top of this, in your commercial and industrial facilities, you still have life safety systems. This can vary from emergency lighting systems, fire pump systems, etc. Those are also required to be selectively coordinated to some level.

All-in-all, you have to have the coordination study and the arc flash study both from a perspective of coding standards.

Why are Arc Flash Studies Important?

Arc Flash Studies are important for 2 main reasons:

  1. Keeping your facility operational
  2. Keeping you and your employees safe

Depending on the facility you have, if you have a miscoordination occur and a fault takes down your operation, that could be significant money loss for your facility. If you have an issue where this leads to damaged equipment, you can be waiting weeks, months, years at this point. In other words, downtime is a huge cost and lead times can be long.

As for safety, say you don’t do the analysis and make sure your systems are up and operational in a safe manner. You could be putting all of our employees at risk. Not only your actual electricians that are going into the equipment and making changes to it., but also anybody that is exposed to electrical equipment. A lot of facilities do not have separate electrical rooms, meaning other people have access to that room -plumbers, carpenters, office personnel, etc. If that equipment is not properly maintained and if the proper analysis is not performed to ensure safety, that puts everybody at risk.

Why Eaton? Why ErieTec?

What makes Eaton a little different it that they are a manufacturer of equipment. So, when Eaton talks about bus orientation in the equipment or what the ratings are of breakers and fuses, Eaton manufactures those devices. They are also part of testing of those devices, whether it be manufacturing or going the whole way back to getting certifications and understanding all those tests that that device had to go through.

Additionally, they have the experience needed both in the field and in training to ensure an accurate analysis to keep you, your team and your equipment safe and operational.

If you have questions or would like more information on arc flash studies or any related services, please contact us at ErieTec.

Check out our latest blog to learn more about arc flash training and a new NFPA standard and how it affects you and your operations.