Hi. I am the manager of a service company and I would like to think I am well versed in the OSHA and NFPA70E standards. We do everything we can to make a system completely voltage free before we go in and change parts. With that being said, we work on UPS systems that are connected to critical pieces of equipment that do not allow for a full system outage. We usually mitigate this by having our customers install external bypass switches. This allows full isolation of the UPS. Unfortunately, we have legacy systems that only have a bypass switch that is mounted on the UPS itself. In these circumstances it is impossible to remove the bypass supply from inside the UPS. This is usually only 120Vac. Is covering the bypass switch terminals with an electrical blanket and discussing this in a JSA enough to allow work on the parts that have no voltage on them without electrical gloves? Our issue is that replacing parts with electrical gloves and an arc flash shield may cause more safety issues than the work itself. I am sure we are not the only industry that has to deal with these situations. We want to make sure we comply, keep our workers safe but also get the job done. Any comments would be appreciated.

Unfortunately, just reducing or eliminating the shock hazard would not be enough. You also need be aware of the Arc Flash Hazard. There are two sources of Arc Flash in a UPS. You have the AC arc flash from the utility source and a DC arc flash hazard from the batteries. The arc flash energy can be calculated using the AC equations in IEEE 1584 - 2018 and DC equations in NFPA 70E.

But, you need to ask yourself is it Infeasible to turn off the UPS or just inconvenient? My guess is that it is inconvenient. Shutting down the UPS will not create loss of life or additional hazards.

Similar problems come up with ATS's. The fact is that they are generally low cost commercial grade designs as opposed to more of main breaker arrangements such as main-tie-mains that you see in industrial facilities.

An arc flash blanket is designed to contain the force of an arc flash but there is still minimal PPE that goes along with it (head to toe arc flash PPE). The blanket contains most of it but hot gasses still come around the edges, so that still probably doesn't get you where you are trying to get to since gloves are still necessary although if you've eliminated a shock hazard you can drop down to say all leather gloves.

The issue is more similar to MCC buckets. The question really should be...what does the TASK entail? With the disconnect open are there exposed conductors? Keep in mind that guarded is NOT exposed. Just because you can see copper doesn't mean anything. We want insulated, guarded, or inaccessible. Alternatively is the work more than the restricted approach boundary away? If so, then you're outside the shock boundary. In many cases you can get rubber blankets (not the same as arc flash blankets) or use other insulating materials and manually insulate it if it turns out to be exposed. This is routinely practiced by linemen using line hose and/or rubber blankets. That's the red rubber sheathing you see on lines when they're working multiple circuits, and they use this stuff a lot so it's proven technology.

Once you've done that, what is it that you are working on that can CAUSE an arcing fault? The biggest concern is usually a dropped component or tool. Even this can be mitigated. Insulated tools often leave a tiny area exposed which is less than that necessary to cause a phase-to-phase fault across bus bars so it can't cause an arcing fault even if you do drop the tool.

In other words, the energized area at the top of the breaker is usually not a problem but you have to look at the overall task and whether or not you might cause an arcing fault in the first place.

As to DC arc flash take a look at the public inputs for NFPA 70E-2021. There is a public input that might be of interest to you. DC arc flash even at extremely large battery sizes (utility power plant sizes) is around 1.2 cal/cm2 in extreme cases which don't exist in practice (1/4" gap or smaller) for 125 VDC batteries. At higher voltage it's a problem but when you run the calculations usually the incident energy is down in the dirt.

Paul
Thanks for the reply. This is where my confusion is as there is not a great deal of clarity on what is exposed in NFPA70E. I found this definition:
Exposed (as applied to live parts) – Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated.
Now, the gotcha word is suitably. What does suitably mean? If I cover the live terminals with an electrically rated blanket safe to the terminal voltages and attach it in a way that it cannot move then I would assume that it is suitably insulated. Therefore the work can be performed without the need for the arc flash protection because we can now say that the part cannot be inadvertently touched or approached.
If we document this and we get audited would this stand up?

One of the tricks is that your technicians in the field should NOT feel that they are any sort of time pressure due to safety. They are there to perform the work no matter how long it takes. They inform the office (dispatch/scheduling) of progress, problems, etc., and follow the scheduler who makes decisions as to timing. The exception is when the plant wants them to do something dangerous (violates your company rules). In that case, they call it in and if the office calls it, pack up and leave. Frequently I find myself being the only guy in the plant with a lock on anything and I've never had an issue with going above and beyond plant rules. The only real "audit trap" is doing something less than local plant rules. One of the tricks with training your personnel is this issue of feeling any sort of time crunch. This includes not getting irate with the customer about safety procedures even when it wastes your time. I kid you not I once went to a customer in Virginia to change a thermocouple out. It was quite literally a 15 minute job with 2 hours of driving each way to reach them. It took 6.5 hours on site to complete the job and we ended up doing overtime on this. So there was 6.25 hours of safety procedures, 0.25 hours of work, 4 hours of windshield time. Very frustrating day.

It sounds like you get it as far as actual safety and actual rules go. Your particular equipment is tricky from the sense that you can NEVER shut power off. I'm not talking about the AC side of things. I'm talking about batteries which are always inherently live. So when it comes to energized work the line "infeasible" applies here. It is physically impossible to make a battery jar "dead".

So let's move on to surviving an audit. First off let's just say that as contractors we "sleep around". Their house, their rules. As long as their rules are at least as safe as your rules, you follow theirs. If your rules are more strict, follow yours. This is one of the problems with managing service technicians...the tendency is towards getting very relaxed with safety rules when you are constantly dealing with the various interpretations and tending towards the worst examples (not locking out, not testing for voltage, no arc flash gear when necessary, etc.). For instance if your point of contact just throws the breaker and says go to it, your crew should take steps to lock out the breaker, test for absence of voltage, etc. On the other hand if you're in say a power plant and they have 4 hours of safety training and then they take 2 hours doing a LOTO with 5 pages of forms, you go with it. As I said their house, their rules as long as their rules are at least as strict as yours.

During walk down/through, it pays to pay close attention to this. State what you are doing and have an open discussion about how to lock out a piece of equipment. Your crew knows what they are doing but that's not the purpose...it's to get the plant to explain how they interpret the rules. In some cases it's pretty obvious and not much discussion is needed. When your contact is wearing a business suit and says that he hasn't been in the utility room before in his life, obviously you follow your rules. But in a power plant where they have some crazy complicated LOTO procedures and contractors aren't allowed to even use their own locks, obviously their rules apply. Always leave safety rules in the hands of the customer. That's your key to survival on audits.

You have to remember that your rules makes you compliant with NFPA 70E but there are many interpretations, many of them very wrong, with NFPA 70E. Electrical equipment is NOT inherently dangerous. If that were the case it would not be allowed to be used. We'd still be using steam or pneumatic power. Don't get me wrong...pneumatic control loops still exist and work very well. It is only when the electrical equipment is damaged and thus the safety of it comes into question, or when we are performing certain tasks on energized equipment, where the tasks we are performing or the safety features such as doors are removed for access, that the normally safe conditions no longer apply. That is why for instance we get into the idea of qualified electrical workers, personnel that are trained on how to work on electrical equipment safely even when it is energized. In fact as qualified electrical workers one of our jobs is to inspect and test damaged electrical equipment and if possible, restore it to normal safe operation. NFPA 70E doesn't state that outright but that's one of our jobs. So as qualified electrical workers we can and must take safety seriously and personally because we are directly responsible for determining what is safe and what isn't. It's this personal involvement that is unique to our craft compared to almost all others. It's the fact that occasionally there are only a few millimeters or plastic or rubber that separates us from certain death that makes our jobs different from others around us. Non-qualified workers don't understand this. Safety department personnel in particular feel that they are the sole determination of what is safe and what isn't and that they play God...spending every day trying to protect everyone around them from themselves. They are the least qualified to make decisions when it comes to electrical safety and the fact that qualified workers are more qualified freaks them out because it challenges their power and authority.

The auditor is frequently not trained and has no clue what they are looking at. And they are frequently "trained" by professional engineers and/or safety generalists who are also not trained in performing electrical work and have no clue what they are doing either when it comes to training, that are frequently teaching personnel that contrary to every safety code and requirement out there that electrical equipment is inherently dangerous. So we enter a sort of Twilight Zone of electrical rules. For example Bridgestone has corporate rules that specify that electrical equipment cannot be worked on while energized over 50 Volts, period. Their plants are full of industrial control panels most of which have 120 V controls. They have an use medium voltage distribution equipment and often their "power houses" have medium voltage air compressors in them. And that's never mind the regulatory requirement to test for absence of voltage which is clearly energized work. So if you follow their rules the way that they are written, you can't perform any electrical work, de-energized or not, because you cannot perform an electrical LOTO following OSHA 1910 Subchapter S. They attempted to follow 1910.147 despite the fact that .147 specifically states that it is not for electrical work. So when it comes to Bridgestone we're always having to deal with "exceptions" or some kind of crazy invalid interpretation of how to handle things. Just let them know up front and let them fall on their own swords...they will eventually come to their senses. Pay attention to this kind of stupidity up front when you get the "site specific" training so that you're prepared for it when it happens. Do NOT attempt to question it during the site specific training part of the visit because whoever you are dealing with won't understand the problem. It is far easier to explain with the panels open right there in front of them. They will eventually either get it right or you get paid to show up for a service call but don't actually perform the work. Simple as that.

There are two areas where you will run into the "audit problem". First off yes you cannot avoid doing energized work on UPS systems. That's actually true of ANY electrical system. You will run frequently into two areas even if you just want to practice de-energized work. The first one that I've hinted at is testing for absence of voltage. And I can go further in stating that it's not just that one. You also have to test FOR voltage. For example battery charger preventative maintenance requirements are that you test for ripple which can only be done with the charger energized. You might be able to read the display on the battery charger but then you are assuming that the equipment that you are actually testing is functioning rather than using a separate certified, known working, meter...not good practice. However 70E is really clear on this. You can do energized work when the work is infeasible to perform while de-energized and voltage testing is clearly that, AND it has an exception in that energized work permits are not necessary for voltage testing. This exception exists because it recognizes that energized work is always necessary for voltage testing so that you aren't using the permits frivolously, only using them when actually necessary.

The second issue that I mentioned earlier is that batteries are ALWAYS energized. There is no such thing as a de-energized battery even straight from the factory. Totally de-energizing a battery runs the risk of cell reversal among other problems, destroying the battery. But in this case sometimes you can't avoid the energized work permit issue. So again leave it in the hands of plant personnel and go with it. They may or may not require the form. Again, let them fall on their own swords.

We run into this issue frequently as a motor shop. Some examples of this kind of problem are:
1. Incident energy analysis. About half haven't done it. Many times even the ones with an engineered study are screwed up. For instance the labels are blatantly invalid with the "inherently dangerous" labels and they don't have procedures for dealing with this. So you have to use the 70E tables as part of your job frequently, and watch them fall on their swords in other cases.
2. Checking for rotation direction. Most of the time we are more qualified to check for rotation direction than plant personnel but it's a frequent trap. We state up front that we aren't familiar with their equipment and make them give us a thumbs up/thumbs down. That way we aren't ever responsible for equipment damage because the rotation direction is wrong. VERY important on compressors for instance.
3. Energized work permits and energized work procedures. We let them figure it out. We have our procedures but remember that it's their house, their rules. As long as their rules are not inherently dangerous in which case you follow your rules first.
4. Testing with a meter vs. with a tic (noncontact voltage tester) vs. just sticking a lock on it and hoping for the best (aka 1910.147 rules). The standards require a meter for testing below 1000 V when testing for absence of voltage (safety), and using a tic above that. Some plants all but ban tics because of people trying to use them below 1000 V so we get into an issue when I have to do LOTO on a 4160 V motor. Others want to use a tic for everything so then I stick a meter on it under 1000 V.

Thanks for the replies.

How about this specific scenario:

We are working inside a panel. All power is isolated except for a 120Vac circuit which takes power in and then it goes directly back out of the panel. It does not feed anything else inside the panel. This is feeding a safety critical load at this time that cannot be turned off. We need to change a component in the panel in an area that is within 2ft of the live circuit but has been verified as de-energized. The decision is made to completely cover the live circuit terminals with electrically rated insulated matting in a way that it cannot move while work is being performed. A full JSA and permit is written explaining the risk assessment.

We have two questions:
1. Does this meet with NFPA70E and OSHA standards for safe work?
2. Does the technician still need to wear arc flash PPE to perform the work? I would think that covering the exposed live conductor means it is no longer exposed and therefore not an arc flash hazard.

Thanks

First before we do anything when we are talking about lockout/tagout which appears to be where you are going, did you know that there are literally over a dozen lockout procedures in OSHA regulations? I'm not talking about simply individual rules but whole procedures! The most well known is the general LOTO procedure. This is in 1910, Subchapter J. Even though it does not apply for instance to construction, it is the most often referenced procedure and almost everyone thinks that it is the one and only LOTO procedure, and they are flat out wrong. Subchapter J specifically states that it is not for electrical work. There is one LOTO procedure for utilization equipment which falls under Subchapter S (1910.3xx) and four more that are in Subchapter R section 1910.369. Construction has just two sentences over in Article 1926 but that one really probably isn't even all that adequate by OSHA's own standards. So focusing on your situation, is the equipment you are dealing with utilization equipment? Or is it "generation, transmission, and distribution" equipment? Second is it continuous duty and interacts with the utility line power or is it strictly portable or emergency backup power such as backup generator that operates only exclusive to utility power? Don't be afraid to get confused on the answer to this question because when you look at the "scope" section of NEC (NFPA 70), 70E, and NESC (IEEE C2) never mind OSHA it is clear that nobody else is very good at defining the scope of what you are dealing with either.

Now why am I making this distinction? For the simple reason that we've got to make sure that we are following the right set of rules!! The prohibition against energized work exists ONLY in Subchapter S which applies only to utilization equipment. It does not exist for distribution equipment (1910.269). And they have 4 different LOTO procedures so make sure you pick the right one.

This is an important distinction. If you are working on distribution equipment, then you should be following 1910.269, NOT Subchapter S. And if you read the scope in 70E carefully at the very beginning, you will also find that 70E does not apply either. That's not to say that you can't use it as a guide,just that there are differences between the two rule sets.

Read this standard letter of interpretation from OSHA:
https://www.osha.gov/laws-regs/standard ... 2006-12-19

"Therefore, to qualify for the exception found in Note 2 of §1910.333(a)(1), the employer must, on a case-by-case basis, determine if the orderly shutdown of the related equipment (including the panel) and processes would introduce additional or increased hazards. If so, then the employer may perform the work using the electrical safe work practices found in §§1910.331-1910.335, including, but not limited to, insulated tools, shields, barrier, and personal protective equipment. If the orderly shutdown of the related equipment and processes would not introduce additional or increased hazards, but merely alter or interrupt production, then the de-energization of the equipment would be considered feasible, and the exception found in Note 2 of §1910.333(a)(1) would not apply."

This goes beyond the mere statement of looking at the panel itself in question and this is where the term "continuous industrial processes" comes into play. Does the orderly shutdown of the RELATED equipment and processes introduce additional or increased hazards and not merely alter or interrupt production? You can't just stop at the panel itself and that's where this term (and its misuse) come from. I have spent many a late night at hospitals due to working on equipment that affects operating rooms and far too many weekends at large manufacturing plants for this reason. Switchgear guys work by flashlight more than they do by sunlight! You have to expand beyond your immediate surroundings. Your statement, "safety critical load at this time that cannot be turned off" does not meet this criteria.

However the prohibition against energized work comes from Subchapter S, NOT 1910.269 which has no such prohibition. It is recognized that distribution equipment is different. It is generally difficult to get things shut down in an orderly manner. It is meant to be worked on while energized. Work procedures have been developed specifically for this purpose. So if you consider a UPS to be distribution equipment, then you probably should be working under 1910.269, not Subchapter S. And that means that you should be using NESC more than 70E and NEC. But there are a few other differences as well so don't just take this one section and run with it.

Next regardless of which rule set you follow when you do an electrical LOTO you MUST test for absence of voltage. A case can be made for certain procedures such as visually verifying that a generator is shut off or that a cord has been disconnected but most of the time this means doing a voltage test. Equipment is always considered to be POTENTIALLY live until you prove (via a test) that it is dead. So that means that the test for absence of voltage is ALWAYS energized work. There is also personal protective grounding if it is needed and that is also ALWAYS energized work. A third bit of energized work is if you are applying cover up., which is what you are talking about doing. This web site shows some nice pictures of cover up illustrating it:

https://www.osha.gov/SLTC/etools/electr ... pment.html

So getting back to your questions. First off, forget about 70E when it comes to shock protection. No matter how hard they try, they just can't get it right. Cover up is a standard practice. Even the OSHA letter of interpretation basically mentions it. It has been stricken from 70E because some on the committee think that this is strictly a lineman thing and has no place in a utilization standard, and they would be dead wrong. So rather than bother with that I'd suggest studying IEEE 516 which is the standard that 70E and OSHA actually reference and use as the guidance for shock protection.

In terms of shock protection there are three considerations. The first one is whether or not you are protected by distance. The key criteria for qualified workers (qualified means they are trained to do energized work) is the minimum approach boundary. For some goofy reason NFPA 70E renamed this term to the "restricted approach boundary". Same thing. The second boundary applies to unqualified personnel. This boundary exists but is never named in OSHA 1910.269 and elsewhere. It is called the limited approach boundary in 70E. It is generally either 3'6" or 10' for the voltages you are referring to based on whether or not the conductors are basically fixed or they can swing (overhead lines). Since you said you are 2 feet away, we're actually done here. No need for cover up at all because you are never crossing the minimum approach distance. A further consideration is whether or not equipment is exposed which means it is not insulated, guarded, or inaccessible such as behind a door or panel. If it is not exposed, then the approach boundaries are ZERO (they do not exist). Either way, you're already outside of that area.

If we work within the minimum approach distance, we need insulation. So either we insulate the tools such as working with meters with insulated probes or hot sticks, or we use insulation on ourselves (rubber gloves with leather protectors), or we insulate the equipment using cover up. If it's the latter we get the gloves out to put it on then we can take them off because after that, nothing is exposed.

When switching over to arc flash the key consideration is whether or not we can accidentally create an arc. If there is exposed equipment and we bring conductive objects into the minimum approach boundary, then it is generally ASSUMED that an arc is possible by accidentally contacting the energized parts. But if nothing is exposed then we have to consider any other way that this might happen accidentally and if not, we don't need arc flash PPE. The first table in 70E-2015 or -2018 covers this situation, and alternatively there is a table in Annex A of 1910.269 that I consider far more readable and better written than the long, complicated, and confusing table in 70E. If there is nothing exposed and no way to accidentally create an arc then arc flash PPE is not needed. Otherwise, it is.

Don't get caught in thinking EXPOSED = arc and and shock hazard and not EXPOSED = no arc flash or shock hazard. By way of example inserting an MCC bucket into an energized MCC (not that I condone this practice) is certainly an arc flash hazard and there have been more than one documented case of injury from this practice. However there isn't a shock hazard when doing this because the bus is behind the bucket where it can hardly be considered exposed.