So how do you mark an arc flash boundary? Electrical safety barriers come in different sizes, some companies rely on floor tape while others use cones and rope to block off the area completely.Ī key factor is that no matter which material you use for the arc flash boundary barricades ensure that your team knows exactly what the electrical safety perimeter barriers means. Now that you know the correct boundary to use its time to setup the barricade. Just put up the barricades and be done with it. I mean why wouldn't you want to do this anyway, it'd be great, no supervisor breathing down your neck, and no operations team asking you every two minutes if you are done yet! Really all an electrician needs to remember is every time you are exposing energized parts you should be setting up barricades to keep unwanted people away.Įssentially the limited approach boundary is the distance at which unqualified workers should be at a minimum, if the limited approach boundary is lower than the arc flash boundary the arc flash boundary distance is where the barricades need to be setup. If you have no business being anywhere near exposed energized parts then stay out of this area. The limited approach boundary is similar to the arc flash boundary. This distance is the restricted approach boundary (with a little bit of a safety factor built-in I'm sure). Well, the boundary is imaginary so there really is nothing stopping them from crossing it without gloves but it's definitely not recommended.Īir acts as an insulator, so that's why you don't see lightning bolts shooting out of the power lines while you drive down the street.īut you don't necessarily need to come in contact with those power lines for it to arc across and give you a shock, you just need to come within a certain distance. For the restricted approach boundary distance in Canada refer to CSA Z462 table 1A listed above, a similar table can also be found in NFPA70E. The restricted approach boundary can be defined as the furthest distance away from exposed energized conductors that an electrician can come without wearing rubber insulated gloves. Example if the arc flash boundary is 1.5ft and limited approach boundary is 3.5ft use the limited approach boundary distance to setup a barricade. So, what is the difference between arc flash boundary and limited approach boundary? As shown in the table 1A above, the limited approach barrier is based on a voltage range where the arc flash boundary is based on the hazard level, the higher the level the further away the distance.Īn important factor to note is that you should use the higher of the two distance numbers to setup the barricade. Arc flash boundary vs limited approach boundary Two, add some distance to whatever the label says because I wouldn't want anyone standing where they can get a second-degree burn. One, set up barricades to keep bystanders outside of the arc flash hazard boundary limits. There are two important takeaways from this. They used to call it the arc flash protection boundary until someone pointed out that it did not protect anyone from anything (well maybe third-degree burns).īut how do you determine the arc flash boundary? This is where an arc flash study comes in, a study will highlight on each piece of equipment the exact distance to be away from in order to setup the correct arc flash boundary marking. The arc flash boundary is the distance away from an arc flash where someone would be able to receive a second-degree burn. just kidding) then you would be exposed to an arc flash of much less magnitude. The important thing to remember is that if you were working on a piece of equipment and you were closer than the assumed working distance you would be exposed to a greater arc flash incident energy level than what is posted on the label.Ĭonversely, if you were able to take a few steps back from the equipment and continue your work (maybe with a broomstick. Since most arc flashes occur when someone is performing work on a prospective piece of equipment it only makes sense to calculate the arc flash at that assumed working distance. You see, distance is a key component to calculating an arc flash, so the engineer needs to make an educated guess as to where someone might be when an arc flash happens. So what is arc flash working distance? The working distance is in reference to the arc flash incident energy and it is actually the distance that you are assumed to be standing at while working. If the engineer followed the recommendations in CSAZ462 workplace electrical safety then each label should have listed the following: The CZA Z462 :21 Table 1A is a great resource for both a restricted approach boundary table and a limited approach boundary table. Most industrial facilities have gotten around to completing an arc flash incident energy analysis and posted labels (or stickers) on all of the electrical equipment.
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