Entering Electrical Panels -Industrial Environment


Thread Starter


I'm new here... anyone have a firm definition of "competent person" (in Ontario, Canada) for entering a panel? Must the panel be de-energized or do I need the "Michelin Man" suit?

I'm fairly conversant with the Z642 - Arc Flash rule. I have two situations causing us grief. one has been visited in this forum. From time to time, someone must enter a "LIVE" electrical panel to hook up a PC to a PLC. If my panel is designed such that the highest voltage in the PLC panel is 120V ac, my understanding is that, save for a pair of leathers, Arc Flash gear is unnecessary.

The second issue is entering a power panel (less than 600V) to reset an electromechanical overload. I realize this is not a "control" issue, but the rules would be the same, would they not?
If you are not aware of the sites electrical policy you are not a competent person. Talk w/the site electrician or maintenance manager. If it is a large facility they have probably done arc flash studies on all panels and it would be posted at the panel. You may have to wear safety glasses, leather gloves and even FR rated clothing to enter the 120 volt panel. It would depend on the facility and their rules. the 600 volt panel probably has an arc flash hazard and judging by your questions your should probably just have an individual knowledgeable of the hazards hook your laptop up or you.
I thank you for your informative response. It does not, however, answer the question directly. Can I infer that a company can write a policy with their own definition of "competent person"? I have worked in facilities where such company procedures exist. Unfortunately, the place I'm in now isn't one of them.
I have no idea about Canada, but here in the US, companies can write their own safety program. and it is what it is until someone gets injured or someone reports the company to OSHA for an unsafe procedure. Short story, the company's documented safety program cannot underscore OSHA mandates on safety.

In general, arc flash hazard analysis must be performed for potentially energized equipment, and appropriate PPE must be donned prior to verified lockout. To work in energized equipment enclosures other than for lockout verification testing requires an "act of congress". Perhaps overly exaggerated, but I think you get the idea.
I thank you for the time and thought put into your answer. What I was hoping for was "something" in print that could save me the aggravation of a late-night call to plug in a laptop for a techie or take 5 minutes to reset an overload - after a 40 minute drive to get to the plant! Our unwritten policy here is "electrician only" for panel access. Yes, despite all the changes I've seen in 25 years as an electrician, managerial incompetence is still flourishing.

Curt Wuollet

That's probably why it's so widely ignored, it's unworkable for troubleshooting.

Any reasonable compromise would probably improve compliance. Costing industry millions in downtime, etc. to prevent the very few accidents and injuries relative to the installed base is seen as unreasonable by even safety minded business types. There are far greater dangers to worry about in most plants where the services are 480 V, which covers the majority. I'm certain heatstroke kills more people, the equivalent reaction would be to require air conditioning in _every_ plant.


Bob Peterson

It is always up to the employer to determine what tasks an employee is to perform and to determine if he is "qualified" to perform those tasks.

Some companies do this in more formal ways than others, but all of them make these decisions in some way.

OSHA has selected NFPA70E as kind of a baseline for electrical safety. If you adopt it, you won't get fined for not having an electrical safety plan which is required. You can have your own plan if you want, but if something goes wrong, you have to defend your plan as being "as safe as" NFPA70E. Since NFPA70E is so widespread and straightforward, and pretty simple and relatively cost effective to implement, there is no reason to make one's own plan up.

Part of the problem with NFPA70E is that there is widespread ignorance about what it actually involves, even among people who think they know. At its core, it deals with just two hazards associated with electricity. One hazard is electrocution and the other is arc blast.

Employers are required to protect their employees from all hazards, so they have to deal with these two.

Fortunately, one can protect most employees from the hazards associated with electricity by distance. Just stay away. NFPA70E defines certain boundaries where all "unqualified" people are prohibited from being when there is a risk of exposure to electrical hazards.

It also defines certain precautions for prevention of electrocution. Distance is one of them. The other thing is that for the most part, working on equipment with the power on is just prohibited entirely. OSHA does not care if this is inconvenient, or if it results in loss of production. You just plain cannot work on energized circuits, with a very few exceptions.

Two of the exceptions are to verify that the power has actually been removed from a circuit prior to working on it, and the other is for debugging. However, even if you are allowed to do live work, if you get close enough to energized circuits >50V you are required to be both "qualified" and wear appropriate PPE. One of the PPE items that is required is insulating gloves. That's right. If you are debugging things in a live panel, you are almost certainly required under any rational electrical safety program to be wearing gloves to protect you from the risk of electrocution, along with the other PPE required. Gloves are the big issue with most people because they are so difficult to work with.

The other hazard is a bit mor problematic. Arc blast is a tough one to deal with. before you can even consider dealing with it, you have to determine how much incident energy is available. This is non-trivial and expensive, but you cannot protect employees from arc blast without it. Once you have determined how much IE is available at a panel, you put a sign on the panel noting this and what PPE is required to protect one from the risk of arc blast if one goes into the panel while it is energized (including such things as verifying that power has been shut off).

There are various levels of PPE that are designed to protect against arc blast. The moon suit is just part of it. However, IE above 40 kcal/cm2 is considered too dangerous no matter what level of PPE is worn so under no circumstances ever can equipment with this level of IE ever be worked on while energized. There are things that competent engineering can do to reduce the level of IE. There are also things that can be done such as remote racking that eliminate the risk to human beings, while not eliminating the risk of the arc blast itself.