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 Post subject: Practicality of confirming de-energized wearing insulating gloves
PostPosted: Tue Aug 13, 2013 1:45 pm 
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If I am understanding it correctly, Table 4A of Z462 Workplace Electrical Safety categorizes the verification step that the power is off on equipment that has previously been turned off, locked out and tagged out as a Risk Category 2 requiring electrically insulating gloves. Is that practical, handling and operating a multimeter and precision placing the probes while encumbered with thick insulating gloves? Whether practical or not, what percentage of workers don electrical gloves to verify something is completely de-energized (with no energized line side components exposed)?

Thanks for your responses.

Mike


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PostPosted: Tue Aug 13, 2013 10:15 pm 
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Keep in mind this is another part of the standard where you have to keep one thing very clear in your mind. Arc flash and shock are two totally different hazards. The methods to avoid them are completely different. Do NOT mix them up or you will either leave yourself vulnerable or create confusion and poor decision making.

Contrary to popular belief, the tables do NOT mandate shock protection PPE. The tables are not mentioned or referred to in any way in the sections on shock protection. Instead it cryptically refers to using various methods to provide shock protection. A more enlightening document is IEEE 516 which Z462 (and nearly every other standard for shock protection) use. Make sure to get the 2009 edition or later...earlier editions contain some errors.

If you do read IEEE 516 then it becomes clear that insulated tools are an acceptable work method. So holding the insulated probes of your meter if it has some sort of guard to prevent your hand from accidentally slipping off the insulated handles and onto the energized probe is acceptable. Insulated tools methods are well documented in IEEE 516. Z462 (and 70E) are just about as vague as it gets. They mention various work methods but don't specify what any of it means. In older versions of IEEE 516 it used to mandate rubber gloves for all tasks. Clearly this is silly and violates the concepts of primary and secondary insulation at 69 kV and above especially where there is no available glove. At that point the only available energized work methods are bare hands and insulated tools. However carefully reading and understanding IEEE 516 also makes it clear that ANY work method specified such as using insulated tools OR gloves OR de-energized work OR working from an aerial lift platform (bucket truck), OR several other mehtods are all acceptable methods of providing adequate shock protection.

However, here's the rub. The tables are only referenced in the section on arc flash hazards and detail how to provide arc flash protection in lieu of performing engineering calculations and doing a full risk assessment. If you use the tables then for certain tasks it specifies that rubber gloves are worn. This is an assumption made for arc flash purposes, NOT shock protection. Rubber gloves actually provide extremely good arc flash protection. If you use the task tables, then you need to follow them to the letter for arc flash protection. Shock protection is a separate issue, but if the tables specify rubber gloves then they need to be worn for arc flash protection purposes, not shock protection.

So if you have no exposed conductors then you don't need rubber gloves in the first place. If you are using an insulated tool such as meter probes, then again, rubber gloves are not necessary. You may still have to wear gloves for arc flash purposes though, either leather or arc flash gloves, or rubber, depending on the circumstance and what works best.


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PostPosted: Mon Aug 19, 2013 10:43 am 
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OK, I am a bit confused by this question. Is it not a requirement of every lock-out tag-out procedure that the de-energized state of the equipment be verified before the equipment can be tagged as safe to work on. Or is every worker who approaches locked-out tagged-out equipment required to re-verify the de-energized state using Category 2 protection? (Personally, I never completely trust any lock-out tag-out and always perform my own verification every time I approach the equipment to work on it. In millwide shutdowns with massive group lock-out tag-outs I am even more paranoid and assume every circuit could become live by accident at any instant.)


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PostPosted: Mon Aug 19, 2013 12:36 pm 
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Mike,
We use class 0 gloves and leather protectors and have no trouble handling a multimeter and probes.

David,
We only check for de-energization when we are going to make contact with an electrical component. Otherwise we use lock and try.


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PostPosted: Tue Aug 20, 2013 6:32 am 
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OK, I am still confused. IF we were to find an energized component in locked out tagged out equipment then is it not true that the lockout tagout procedure has been a complete failure? And if this is true, then don't we have to re-think the whole system of making equipment safe to work on?


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PostPosted: Tue Aug 20, 2013 6:47 am 
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Lock and Try? Doesn't that conflict with NFPA 70E?

From NFPA 70E:
120.3(A) General. All electrical circuit conductors and circuit parts shall be considered energized until the source(s) of energy is (are) removed, at which time they shall be considered de-energized. All electrical conductors and circuit parts shall not be considered to be in an electrically safe work condition until all of the applicable requirements of Article 120 have been met.

One of the requirement is to test for absence of voltage with an adequately rated voltage detector. Also 130.2 States:

130.2 Electrically Safe Working Conditions. Energized electrical conductors and circuit parts to which an employee might be exposed shall be put into an electrically safe work condition before an employee performs work if either of the following conditions exist:
(1) The employee is within the limited approach boundary.
(2) The employee interacts with equipment where conductors or circuit parts are not exposed, but an increased risk of injury from an exposure to an arc flash hazard exists.


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PostPosted: Tue Aug 20, 2013 7:20 am 
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K. Cutler, I think the key focal point for this discussion centers around the phrase "might be exposed"(130.2). If there is any possible exposure to conductors or circuit parts then you are right; lock and try would be insufficient and a complete electrically safe work condition would need to be produced through testing for the absence of voltage with an appropriately rated voltmeter. However, if there is no exposure to the electrical conductors then lock and try approach MAY be effective.


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PostPosted: Tue Aug 20, 2013 9:09 am 
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BISAM wrote:

We only check for de-energization when we are going to make contact with an electrical component. Otherwise we use lock and try.

Guess I was thinking about this statement. You could be within the limited approach boundary with exposed conductors even though you do not "intend" to make contact. I'm probably being a bit too analytical about the text. If there is no exposure or interaction that can cause an arc flash, then your approach makes perfect sense. :)


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PostPosted: Thu Aug 22, 2013 11:09 am 
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Sorry. I see where my statement could be written better.
If we are going to tighten the belt on a pulley, we would use lock and try per OSHA.
If we are going to work within the electrical boundaries we would lock out the appropriate energy control device and verify a deenergized state while wearing class 0 gloves and the PPE that is required for the level of arc flash energy. We consider the verification step to be the OSHA "try" step for electrical work.


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PostPosted: Tue Sep 03, 2013 8:39 am 
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Please also keep in mind that electrical circuits may contain components that retain a charge or that charges may be induced from adjacent sources e.i. capacitors, PT/CT racks, rotating armatures, transmission line corridors, etc. during the time that you are making the circuit "safe". The goal is to make the circuit electrically safe. In the utility world, we say... If it isn't grounded, It isn't dead". This is a good time to review the NESC guidelines for LOTO as well. Rubber gloves are worn until the circuit has visible open conditions and the grounds have been applied.


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 Post subject: Re: Practicality of confirming de-energized wearing insulati
PostPosted: Mon Feb 27, 2017 7:28 am 
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As far as "Lock and try", our policy is that if you are going to be working on ANY part that may injure you, then LOTO / Bump Test / Zero Volt Verify is required and signed off for by a qualified person. Things like couplings, pulleys, etc., as well as any in cabinet work. If you are working on non-rotating elements, i.e.: oil changes, greasing, then LOTO / Bump test are sufficient.


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 Post subject: Re: Practicality of confirming de-energized wearing insulati
PostPosted: Tue Feb 28, 2017 1:37 pm 
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Michael Learmonth wrote:
If I am understanding it correctly, Table 4A of Z462 Workplace Electrical Safety categorizes the verification step that the power is off on equipment that has previously been turned off, locked out and tagged out as a Risk Category 2 requiring electrically insulating gloves. Is that practical, handling and operating a multimeter and precision placing the probes while encumbered with thick insulating gloves? Whether practical or not, what percentage of workers don electrical gloves to verify something is completely de-energized (with no energized line side components exposed)?

Thanks for your responses.

Mike


Is it possible that Risk Category 2 for arc flash PPE is being confused with Class 2 for rubber gloves? I believe above 600V a non contact voltmeter is used. Therefore, Class 0 gloves can be used less than 600V and these still have some dexterity and are not "thick insulating gloves".

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www.workplacesafetysolutions.com


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 Post subject: Re: Practicality of confirming de-energized wearing insulati
PostPosted: Thu Mar 02, 2017 8:32 am 
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wbd wrote:
Michael Learmonth wrote:
If I am understanding it correctly, Table 4A of Z462 Workplace Electrical Safety categorizes the verification step that the power is off on equipment that has previously been turned off, locked out and tagged out as a Risk Category 2 requiring electrically insulating gloves. Is that practical, handling and operating a multimeter and precision placing the probes while encumbered with thick insulating gloves? Whether practical or not, what percentage of workers don electrical gloves to verify something is completely de-energized (with no energized line side components exposed)?

Thanks for your responses.

Mike


Is it possible that Risk Category 2 for arc flash PPE is being confused with Class 2 for rubber gloves? I believe above 600V a non contact voltmeter is used. Therefore, Class 0 gloves can be used less than 600V and these still have some dexterity and are not "thick insulating gloves".


Note the dates in this thread. It's an old thread, using the old H/RC tables.

The voltage class is not in question at all. The task was measuring voltage while wearing insulating rubber gloves. In that case the tables gave an H/RC rating of 2. The task table isn't actually mandating shock protection since it's specifically for arc flash protection but to utilize that line of the task table required insulating rubber gloves. I know it sounds very screwed up and it is, but there was a lot of that in the pre-2015 tables.

The cutoff for multimeter type methods using the correct IEC standard IEC 61243-1, 2, 3, 4 series) is 1,000 V. Above 1,000 V you use noncontact methods. Below 1,000 V you use contact methods. The 600 V "limit" is a goofy non-standard limit that has existed in U.S. regulations and Codes for years for historical reasons. The UL/IEC standard 61010 is an instrument construction standard, not a voltage measurement work standard. The latest NEC is already moving the boundaries up to 1,000 V to match international standards for that reason whenever it doesn't conflict too badly with U.S. regulations. It is more congruent with wire insulation standards that have break points at roughly 300, 600, and 2000 V.


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