It is currently Wed Jun 03, 2020 5:44 am



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: Presence of Voltage Indication
PostPosted: Thu Jan 19, 2017 10:42 am 
User avatar

Joined: Tue May 31, 2011 9:03 am
Posts: 13
Location: Davenport
Voltage indicators reduce risk….
….by allowing workers to pre-verify zero voltage before opening the panel door.
Verifying zero voltage inside an electrical panel is a high risk task, and more so, if a worker only has a multi-meter. Installed voltage indicators greatly increases the likelihood that that a worker’s multi-meter verifies that only zero voltage exist at the disconnect switch while performing a lock-out tag-out procedure. In addition, the risk of injury due to the wrong meter or meter setting is also reduced. Voltage indicators are a perfect example of electrical safety-by-design.

….because failed isolators get discovered before becoming a hazard to workers.
A failed disconnect switch is an extremely high risk electrical accident ready-to-happen. When facilities deploy voltage indicators in lock-out tag-out, 25% of these users state that the voltage indicator helped identify at least one or more failed disconnect switches without having to open the panel. Most often, opening a disconnect switches, almost always comes with an assumption of zero voltage inside the enclosure. Perhaps, the assumed complacency by the worker is the primary reason why a failed disconnect switches are so dangerous.

….by having a CAT III/IV (UL 61010-1)* surge rating is the same reliability requirement for industrial multi-meters.
When the wrong multi-meter used in an industrial plants, it could blow-up in a worker’s face as a result of voltage spikes and surges. The CAT surge testing and certification is detailed in the UL 61010-1 is the minimum requirement for a “voltage test instrument” in NFPA 70E 120.1(5). Also, the voltage indicator must have an even more robust design than a multi-meter because it sees most every surge and spike in the power system 24/7/365.

….and exceeds the requirements of NFPA 120.1(1)-(6).
NFPA 120.1(1)-(6) requires that workers follow this correct procedure with an “adequately rated voltage test instrument”—no more, no less. By simply adding a voltage indicator exceeds the NFPA 70E standard. The only caveat; the facility’s lock-out tag-out procedure includes checking the voltage indicator operation before and after each procedure.

….because of a decade long track record of uncompromised reliability.
Some voltage indicators have field tested reliability a calculated mean time between failure rate (MTBF) of 34.79 years. If a false positive voltage indication were to occur (voltage present and no indication) requires that both the voltage indicator and disconnect switch fail simultaneously within minutes of each other which is highly improbable.
When we look at risk reduction from the workers perspective, we find that workers who feel safer are more productive. A recent survey found that facilities using voltage indicators as part of their lock-out tag-out procedures, that 95% of their workers feel safer and more confident when voltage indicators are installed on the equipment that they are servicing.



Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Thu Jan 19, 2017 11:14 am 
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
What is the question?

While I'd agree with the sentiment, let me play devil's advocate here. This argument has been advanced by a couple different voltage indicating companies.

The first one is the idea that voltage indicators aren't a bad idea as a SUPPLEMENT and that's exactly how at least one company advertises them. I don't disagree that it's a big improvement over taking voltage measurements by hand for a lot of reasons but as of right now the codes and regulations that exist don't accept voltage indicators in lieu of hand held testers.

The first one is that UL/IEC 61010 is really not the best "reference". In fact it should NOT even be mentioned in NFPA 70E at all!. This thing is really only a guide on how to build a meter to make it safe and offers no guidance on how to actually test for absence of voltage or what constitutes "safe". NFPA 70E already takes the stance that it is a work method standard for the most part and NOT an equipment standard, an installation standard, or for that matter a risk assessment or incident energy calculation standard (with the exception of the tables). So purely from a philosophical pont of view, it has no business being in there. That's why I raised the issue in a public input.

In fact it's stupid to even use UL 61010 as a standard because for instance multimeters are not an acceptable way to test for absence of voltage above 1 kV and there are multiple documented cases of where an electrician has tried to do this (even before IEC/UL 61010) and things went really, really bad as the now totally under-rated meter turned into a fuse wire and initiated an arc flash at medium voltage where it is never going to self-extinguish.

So moving on...what then? There is currently really no U.S. standard for doing voltage checks. However there is an international standard embodied in IEC 60060-1, -2, -3, and -4. This set of standards covers voltage testing with a multimeter below 1 kV, voltage testing with either a resistive or capacitive tester at 1 kV or above, and permanently mounted voltage indicators. So if we can get away from U.S. based standards and accept that the IEC standard covers what NFPA 70E really should be talking about...how to properly test for absence of voltage, then we get to exactly where you are headed.

Now as to a 34+ year MTBF, frankly that's terrible. That's the same as most transformers and those are hardly something we'd consider a safety device. I'm shocked that it is that low. If you go through the various safety standards that are out there as far as an acceptable failure rate, you get to somewhere between 1 in 100,000 and 1 in 1 million failures per year. Even if we started using redundant voltage indicators to push this out and assume totally random failure rates, that still only gets us to 1 in about a little better than 1 in 1,000.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Thu Jan 19, 2017 1:35 pm 
Sparks Level
User avatar

Joined: Fri Jul 08, 2016 10:01 am
Posts: 227
Location: Indiana
Look at the OP's profile and go to his website and you'll see he sells them.

I don't think he's really asking a question or looking for a discussion. Just marketing.

_________________
SKM jockey for hire


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Fri Jan 20, 2017 5:31 pm 
Arc Level

Joined: Tue Jan 13, 2009 5:00 pm
Posts: 524
phil2331 wrote:
….and exceeds the requirements of NFPA 120.1(1)-(6).
NFPA 120.1(1)-(6) requires that workers follow this correct procedure with an “adequately rated voltage test instrument”—no more, no less. By simply adding a voltage indicator exceeds the NFPA 70E standard.


Time to reread that section, since it does call for more. 120.1(5) calls for testing the test instrument with a known voltage source before and after each test.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Sat Jan 21, 2017 3:18 pm 
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
stevenal wrote:
phil2331 wrote:
….and exceeds the requirements of NFPA 120.1(1)-(6).
NFPA 120.1(1)-(6) requires that workers follow this correct procedure with an “adequately rated voltage test instrument”—no more, no less. By simply adding a voltage indicator exceeds the NFPA 70E standard.


Time to reread that section, since it does call for more. 120.1(5) calls for testing the test instrument with a known voltage source before and after each test.


I forgot this one. That's my other issue with these things. OSHA Subchapter S only requires testing against a known voltage source before testing and not both times, and that's where it is at least theoretically possible to comply with a permanently mounted voltage indicator by looking for presence of voltage before and then looking for absence afterwards. Meeting the letter and spirit means we can only do this if we're doing a LOTO starting from an energized system, which isn't always the case. But it definitely does not meet the NFPA 70E standard because you can't test after the fact, not unless for instance these things are modified to include some kind of "test port" to facilitate testing.

But an even more difficult problem is where they are going to be mounted. As a case in point let's say that we have two nearly identical 2400 V fused disconnects, two nearly identical transformers, and two nearly identical 480 V fused disconnects, with appropriate labels and a lot of conduit between all of them...LOTS of conduits because this point is a major junction/crossover point and modified several times over the years. Now let's suppose for a moment that there is a transformer problem...say someone never connected X0 to anything and now there's obviously a ground fault somewhere. So the transformer terminal compartment needs to be opened and inspected. So just open the disconnect and test for absence of voltage there as well as at the 480 V fused disconnect side and testing with a multimeter there, or alternatively we can test either or both with permanently mounted voltage indicators following OSHA Subchapter S by simply looking for presence of voltage before shutting it down and then again after disconnecting power, locking out, using a ground cluster, etc., etc. That's all that's required, right? Well?

Not so fast. Because I was that electrician around 2005 and what actually happened is that at some point transformer A failed and given a choice between the loads for A and the loads for B, and the length of time to get a new one in, the conduits and cables were all rerouted from the A disconnects over to the B transformer. Later when the new transformer arrived the B disconnects were rerouted and connected to the new "A" transformer. However in the interim nobody swapped labels on the transformers because the intent at least initially was that eventually they'd switch everything back but it turned out to be easier to not do this and so the transformer labels were later identified as "missing" and the "missing" one was updated with...you guessed it, the "A" label. So if you're with me so far essentially the transformers were switched but the labels were never swapped. So when yours truly locked out and tested the 2400 V disconnect and 480 V disconnect properly, but opened the "B" transformer that was in fact labelled as "A"...well, you can see where we have a problem. Nothing bad happened in the end other than a soiled pair of underwear but I came really, really close to having a personal encounter with 2400 V that day.

Now it could be argued to simply put voltage indicators on the transformer enclosure, too, but in reality this whole affair gets really impractical, really quickly. It becomes obvious that testing for absence of voltage at a bare minimum needs to be done at the work site...as in at the specific enclosure where contact is about to be made, EVERY TIME. You can't do that with voltage indicators, or at least not practically.

So I agree with pretty much everything the voltage indicator proponents have to say and I can even get around the annoying guidance in 70E by defaulting back to OSHA in MOST cases. But I simply cannot get around the fact that these things not only don't cover "most" cases but in fact they really don't cover even a modest number of conditions and cases that have caused me issues in the past time and again. Their best use seems to be letting me know that either a non-visible break disconnect (or circuit breaker) has failed to open all 3 sets of contacts. Again...that's supplemental, not safety related. Whether I like it or not, my "trusty" multimeter or "tic" is pretty much the best way to go, even over 15 kV where the practice of "buzzing" still exists in some places and where unlike the 2400 V case, you pretty much KNOW if the line is hot due to the fact that every tool near the power line tells you it is live.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Mon Jan 23, 2017 8:57 am 
User avatar

Joined: Tue May 31, 2011 9:03 am
Posts: 13
Location: Davenport
stevenal wrote:
phil2331 wrote:
….and exceeds the requirements of NFPA 120.1(1)-(6).
NFPA 120.1(1)-(6) requires that workers follow this correct procedure with an “adequately rated voltage test instrument”—no more, no less. By simply adding a voltage indicator exceeds the NFPA 70E standard.


Time to reread that section, since it does call for more. 120.1(5) calls for testing the test instrument with a known voltage source before and after each test.


Read carefully what is written--NFPA 120.1(1)-(6) requires that workers follow this correct procedure with an “adequately rated voltage test instrument” The point was that the entire procedure (1)-(6) needs to be followed--including the "known source" test. Voltage indicators increase the likelihood of workers only have exposure to zero voltage when performing the "mandatory OSHA voltmeter test"


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Tue Jan 24, 2017 4:26 pm 
User avatar

Joined: Tue May 31, 2011 9:03 am
Posts: 13
Location: Davenport
PaulEngr wrote:
What is the question?

While I'd agree with the sentiment, let me play devil's advocate here. This argument has been advanced by a couple different voltage indicating companies.

The first one is the idea that voltage indicators aren't a bad idea as a SUPPLEMENT and that's exactly how at least one company advertises them. I don't disagree that it's a big improvement over taking voltage measurements by hand for a lot of reasons but as of right now the codes and regulations that exist don't accept voltage indicators in lieu of hand held testers.

The first one is that UL/IEC 61010 is really not the best "reference". In fact it should NOT even be mentioned in NFPA 70E at all!. This thing is really only a guide on how to build a meter to make it safe and offers no guidance on how to actually test for absence of voltage or what constitutes "safe". NFPA 70E already takes the stance that it is a work method standard for the most part and NOT an equipment standard, an installation standard, or for that matter a risk assessment or incident energy calculation standard (with the exception of the tables). So purely from a philosophical pont of view, it has no business being in there. That's why I raised the issue in a public input.

In fact it's stupid to even use UL 61010 as a standard because for instance multimeters are not an acceptable way to test for absence of voltage above 1 kV and there are multiple documented cases of where an electrician has tried to do this (even before IEC/UL 61010) and things went really, really bad as the now totally under-rated meter turned into a fuse wire and initiated an arc flash at medium voltage where it is never going to self-extinguish.

So moving on...what then? There is currently really no U.S. standard for doing voltage checks. However there is an international standard embodied in IEC 60060-1, -2, -3, and -4. This set of standards covers voltage testing with a multimeter below 1 kV, voltage testing with either a resistive or capacitive tester at 1 kV or above, and permanently mounted voltage indicators. So if we can get away from U.S. based standards and accept that the IEC standard covers what NFPA 70E really should be talking about...how to properly test for absence of voltage, then we get to exactly where you are headed.

Now as to a 34+ year MTBF, frankly that's terrible. That's the same as most transformers and those are hardly something we'd consider a safety device. I'm shocked that it is that low. If you go through the various safety standards that are out there as far as an acceptable failure rate, you get to somewhere between 1 in 100,000 and 1 in 1 million failures per year. Even if we started using redundant voltage indicators to push this out and assume totally random failure rates, that still only gets us to 1 in about a little better than 1 in 1,000.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Presence of Voltage Indication
PostPosted: Tue Feb 14, 2017 9:42 pm 
Sparks Level

Joined: Sat Nov 21, 2009 10:23 pm
Posts: 107
Location: Ohio
The answer to a lot of these questions can be solved with the new Fluke PRV240 proving unit, do a google. This is a new device that proves the voltmeter and leads are functioning.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 7 hours


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883