Electrical workers need to complete tasks in close proximity to energized electrical conductors at varying voltage levels each and every day. But how do you know what is considered too close? When do you need PPE? And what are the distances that are considered safe for each voltage?
There are a number of key factors that need to be understood and in this post, we will go over the most important ones.
Is it exposed?
If there was one question that you need an answer to it's this one.
Are any of the conductors or circuit parts that carry the electrical energy exposed? In order to answer this, you first need to understand what exactly we are talking about.
Exposed is a term that is used in electrical standards (like CSAZ462 or NFPA70E) but it's slightly misunderstood. Are the bare copper conductors of overhead lines exposed? Are the bare copper components of a switchgear assembly exposed when the doors are open? Without more information, you might think that the answer to these questions is yes, however, in some cases, it might be no.
Ultimately you need to answer yes to another question. Is it possible to come in contact with or come within a safe distance of the bare conductors? Depending on the situation and the work that is being performed, if the bare copper components are capable of being touched or approached closer than a safe distance, then they are exposed.
Can you touch it?
Hopefully, this concept is straight forward.
If you can inadvertently touch energized conductors or circuit parts then you should be wearing PPE.
There is no safe distance. Wear your rubber gloves.
If you are not that close, but close enough that you are starting to question your safety then you need to know what that safe distance is.
What is a safe distance?
Every voltage has a certain distance that it can "jump". If you reached out with your bare hand and came within this limit then you would see a big blue spark fly across the air touch your finger and then... well, you probably wouldn't see too much after that.
The electrical safety standards have a special name for this boundary... they call it the restricted approach boundary.
At very low voltages (less than 150 volts), the distance is almost negligible. Basically, don't touch it.
Once you get above 150 volts and up to 750 volts the acceptable safe distance is 1 foot. This means that when working on exposed energized parts at 480 or 600 volts if your hands come within 1 foot (which they will if you are testing or troubleshooting) then you need to be wearing your rubber insulated gloves.
From 751 to 15,000 volts the safe distance goes to 2 feet 2 inches. Only adding a foot from the last voltage group doesn't seem like much but you have to remember that the numbers have a safety factor built in for inadvertent movements.
Keep in mind before performing your next electrical job that each voltage level has a different approach distance that is considered safe. If you are exposed to energized conductors or circuit parts then you are at risk of an electrical shock and need to implement protective measures.
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