March 24, 2017 | Robert Gheesling |

The No-BS Approach to Arc Flash: A Free Webinar



The point of The No-BS Approach to Arc Flash wasn’t to look at the technical side of arc flash (we have an interview with expert Hugh Hoagland for that).

Instead we wanted to look at arc flash basics, so the next time you’re working on electrical equipment, you take an extra second to make sure you’re being as safe as possible.

Watch The No-BS Approach Now!

 

1. What is Arc Flash:

Arc flash is an electrical explosion that happens on energized equipment like an air condition, conveyor belt or light bulb.

When electrons move back and forth across a conductor — like a wire — a small area out of that conductor is energized.

Voltage can push those electrons off the wire and onto atoms and molecules in the air. These atoms becomes ions because they have an electric charge.

The air around us is a pretty good insulator to stop these ions from causing an explosion, but it’s not perfect.

If another conductor gets inside that energized area — a wrench, moisture in the air, dust build up or your hand — the electrons will travel through that new path.

As the electrons push off between the conductors, an arc occurs. Watch our three-minute explainer video to learn more.

 

2. Approach Boundary Zones:

 
If you have to work on energized equipment the National Fire Protection Association (NFPA) has developed specific approach boundaries designed to protect employees.

 

Flash Protection Boundary (Outer Boundary)

This is the farthest boundary from the energy source. If an arc flash occurred, this boundary is where an employee would be unaffected.

 

Limited Approach Boundary

This is the minimum distance where an unqualified personnel may safely stand. No untrained person can approach an energized item any closer than this boundary. Qualified people must use the appropriate PPE and be trained to perform the required work to cross the limited approach boundary.

arc flash approach boundaries

“Source: Uptime Institute

 

Restricted Approach

This boundary can only be crossed by qualified persons. This boundary may not be crossed without wearing appropriate PPE. Qualified workers must also have a written approved plan for the work that needs to be performed.

 

Prohibited Approach Boundary

Only qualified personnel wearing appropriate PPE can cross a prohibited approach boundary. Workers also need specified training to work on energized equipment, a documented plan justifying the need to perform this work and they must obtain a risk assessment to cross this boundary.

These distances are not consistent between each piece of equipment. Some equipment will have a bigger flash protection boundary. The length of each boundary is determined by NFPA 70E and is based on the voltage of the equipment.

 

3. Arc Flash is NOT Shock:

This is one of the most common misconceptions about arc flash gloves that I encounter. So it wasn’t surprising that the question popped up a few times during the question and answer portion of the webinar.

Let’s keep it simple: Arc flash gloves WILL NOT protect you from a shock hazard.

Shock hazards can be present when you’re at risk for arc flash, but that is why NFPA 70E requires you to be wearing arc flash gloves and rubber insulators.

 
Arc Flash Hazard PPE Categories (NFPA 70E - 2015)

 

4. Arc Thermal Performance Value:

The intensity of an arc flash is measured in calories/centimeter² which is called incident energy (because it’s energy that isn’t supposed to be released).

One calories is equaled to holding your finger directly over a lighter for one second.

When choosing arc flash gloves, you need to look at the glove’s arc thermal performance value (ATPV). ATPV in the incident energy on a glove that gives a 50% chance that enough heat will transfer through the glove to cause the on-set of second-degree burn.

Here’s an example: You have a glove with an ATPV of 8.2 cal/cm². That means if the incident rating of the arc flash is 8.2 cal/cm², you have a 50% chance of getting a second-degree burn.

That’s why the NFPA 70E chart above is so important to follow when donning PPE. Each layer of clothing under arc-rated clothing reduces the heat received by the body by about 50 percent.

 
Adding FR layers under arc-rated clothing doesn’t increase the arc rating of the clothing. It just reduces the heat your body receives; minimizing intensity of burn to your skin.

 

5. How to Prevent an Arc Flash:

Two out of three electrical injuries are a result of a worker error. The only foolproof way to eliminate the risk of arc flash is to de-energize the equipment through lockout/tagout procedures.

After locking a machine out, double check that it is de-energized by taking a voltage reading of the equipment.

 
worker using a multimeter to measure voltage of energized equipment

 
Another preventative measure you can take is performing general maintenance and upkeep on machinery. Make sure contact aren’t corroded, insulation isn’t worn through or thinning and that equipment has been properly installed.

Finally, launder your PPE regularly. If your PPE has any sort of oils or grease on it, that will increase your burns in the event of an arc flash.

 

BONUS Palm Coatings:

When a glove is tested for arc flash under the ASTM F2675 standard, the decision was made to rate a glove based on the least protective area of the glove. Like the back of the hand. A glove may be rated for 8 cal/cm² of arc flash protection. But a neoprene palm coating can provide up to 50 cal/cm² of arc flash protection. Palm coatings are great news for arc flash protection because the palm and fingertips are typically the most vulnerable areas during an arc flash.

Want to try a pair of the world’s thinnest arc flash gloves? Click below to get your FREE sample!

s18kgne arc flash rated gloves
get a sample button

 

Robert Gheesling
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