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 Post subject: Testing to Confirm De-Energized circuits
PostPosted: Mon Dec 17, 2007 10:20 am 
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On 480V equipment, at the SES, often an Arc Flash Study indicates a high Cal rating with no PPE available. Our client has posed the following question, "When de-energized, what PPE and/or procedure should be followed when confirming the piece of equipment is de-energized?". They contend that using a meter is considered working on the equipment.


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PostPosted: Mon Dec 17, 2007 10:58 am 
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Location: St. Louis, MO
For the test to confirm de-energized equipment, you still have to suit up.
The next part of the equation is: What is "high Cal rating with no PPE available?"

They make suits beyond 100 cal. If it's higher then that, I would say double suit???

If you are referring to the "40 cal limit" there is no such thing. We got into this in another thread on this board, but I can't find it at the moment. I challenge anyone to show me the code section in NFPA 70E that says you SHALL NOT work on anything over 40 calories. Certainly it is not advisable, but it is not code enforceable.


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PostPosted: Tue Dec 18, 2007 8:48 am 

Joined: Thu Nov 15, 2007 7:58 am
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Location: NY
[quote="WDeanN"]For the test to confirm de-energized equipment, you still have to suit up.

I always thought that checking dead is performed outside the flash protection barrier using hot stick devices. The necessary application pf portable grounds is accomplished the same way using OSHA TABLE

Table R-6. – AC Live-Line Work Minimum Approach Distance
|
| Distance
|___________________________________________________
Nominal voltage | Phase to ground exposure | Phase to phase exposure
in kilovolts |__________________________|________________________
phase to phase | | | |
| (ft-in) | (m) | (ft-in) | (m)
________________|_____________|____________|_____________|__________
5 to 1.0 | (4) | (4) | (4) | (4)
1.1 to 15.0 | 2-1 | 0.64 | 2-2 | 0.66
15.1 to 36.0 | 2-4 | 0.72 | 2-7 | 0.77
36.1 to 46.0 | 2-7 | 0.77 | 2-10 | 0.85
46.1 to 72.5 | 3-0 | 0.90 | 3-6 | 1.05
72.6 to 121 | 3-2 | 0.95 | 4-3 | 1.29
138 to 145 | 3-7 | 1.09 | 4-11 | 1.50
161 to 169 | 4-0 | 1.22 | 5-8 | 1.71
230 to 242 | 5-3 | 1.59 | 7-6 | 2.27
345 to 362 | 8-6 | 2.59 | 12-6 | 3.80
500 to 550 | 11-3 | 3.42 | 18-1 | 5.50
765 to 800 | 14-11 | 4.53 | 26-0 | 7.91
________________|_____________|____________|_____________|__________
Footnote(1) These distances take into consideration the highest
switching surge an employee will be exposed to on any system with air
as the insulating medium and the maximum voltages shown.
Footnote(2) The clear live-line tool distance shall equal or exceed
the values for the indicated voltage ranges.
Footnote(3) See Appendix B to this section for information on how
the minimum approach distances listed in the tables were derived.
Footnote(4) Avoid contact.


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PostPosted: Tue Dec 18, 2007 9:00 am 

Joined: Thu Nov 15, 2007 7:58 am
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Location: NY
Approach distances

"For the test to confirm de-energized equipment, you still have to suit up."

I thought that checking dead was performed with insulating tools (Hot Sticks) rated at the voltage that may be encountered. Outside the arc-flash boundry If necessary portable grounds are applied the same way.

1910.333(c)(3)(ii)(C)

The person is insulated from all conductive objects at a potential different from that of the energized part.

TABLE S-5 - APPROACH DISTANCES FOR QUALIFIED
EMPLOYEES - ALTERNATING CURRENT

______________________________________________________________
|
Voltage range (phase to phase) | Minimum approach distance
__________________________________|___________________________
|
300V and less ....................| Avoid Contact
Over 300V, not over 750V .........| 1 ft. 0 in. (30.5 cm).
Over 750V, not over 2kV ..........| 1 ft. 6 in. (46 cm).
Over 2kV, not over 15kV ..........| 2 ft. 0 in. (61 cm).
Over 15kV, not over 37kV .........| 3 ft. 0 in. (91 cm).
Over 37kV, not over 87.5kV .......| 3 ft. 6 in. (107 cm).
Over 87.5kV, not over 121kV ......| 4 ft. 0 in. (122 cm).
Over 121kV, not over 140kV .......| 4 ft. 6 in. (137 cm).
__________________________________|___________________________


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PostPosted: Wed Dec 26, 2007 2:28 pm 
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Eric Campbell wrote:
On 480V equipment, at the SES, often an Arc Flash Study indicates a high Cal rating with no PPE available. Our client has posed the following question, "When de-energized, what PPE and/or procedure should be followed when confirming the piece of equipment is de-energized?". They contend that using a meter is considered working on the equipment.


1) There should be a remote way of confirming de-energization that keeps personnel outside of the Zone. I am not personnally aware of this on 480V equipment.

Even if the worker must traverse the arc flash boundary to use the testing equipment, if a longer working distance can be maintained, the PPE requirements might be reduced to where it is under 40Cal/cm2. Etap (and probably other software packages) will perform calculations at differing approach distances.

2) There are manufacturers offering arc blast blankets (in addition to arc flash). It would be interesting to discuss and verify if some kind of angled approach could be achieved, behind arc blast blankets, to allow the work.

3) take a kill on the entire lineup, and install voltage monitors.

These are not orthodox methods, but to keep things workable sometimes takes a little beyond normal recommendations.

Gary B


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PostPosted: Thu Dec 27, 2007 12:11 pm 
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Gary B wrote:
1)

3) take a kill on the entire lineup, and install voltage monitors.

Gary B


I presume that you're taking about permanent indicators that confirms the presence/absence of voltage.


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PostPosted: Fri Jan 04, 2008 9:42 pm 
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LaszloZW wrote:
I presume that you're taking about permanent indicators that confirms the presence/absence of voltage.


That was my thought though I haven't considered what would constitute a fail safe indicator.

Gary B


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PostPosted: Mon Jan 07, 2008 8:12 am 
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Gary B wrote:
That was my thought though I haven't considered what would constitute a fail safe indicator.

Gary B


The wye connected LED indicators can be considered fail safe. They are lit before opening the breaker and dark after you opened it.

http://www.grace-eng.com/newsletters/VoltageVisionPR/VOLTAGE-INDICATORS-10-2005.shtm

http://www.bnl.gov/esh/esc/PDFs/Engineered_Voltage_Measuring_Solutions_for_Lockout_Tagout.pdf

http://marsh.ooi.net/Diversified/UPA-130_series.htm


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PostPosted: Mon Jan 07, 2008 8:50 am 

Joined: Thu Nov 15, 2007 7:58 am
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Location: NY
Check Dead

When any voltage indicator is lit it tells me that the circuit is energized.
When a voltage indicator is out it tells me one of two things .
A- The circuit is dead
B - The circuit is alive and the indicator is defective.
Indicators indicate, nothing more.
A voltage testing device tests for the presence of voltage

1- Checked the test device on a live circuit
2- Check the circuit
3- Recheck the test device on a live circuit

This can be performed using a hot stick to keep out of the arc flash boundry


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PostPosted: Mon Jan 07, 2008 9:02 am 
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Capt Jim wrote:
When any voltage indicator is lit it tells me that the circuit is energized.
When a voltage indicator is out it tells me one of two things .
A- The circuit is dead
B - The circuit is alive and the indicator is defective.
Indicators indicate, nothing more.
A voltage testing device tests for the presence of voltage

1- Checked the test device on a live circuit
2- Check the circuit
3- Recheck the test device on a live circuit

This can be performed using a hot stick to keep out of the arc flash boundry


Read the engineering analysis provided via the link in my previous posting. The likeliness of the LED failing at the same time when the breaker opens is improbable. How would you use a "hot-stick" on a 480V MCC cubicle?

If you wish to test for the functioning of the LED's you can always use a battery on the test-leads. The test-measure-test is a leftover from the coil/magnet driven analog meter time and IMO it's necessity is questionable. I just would like to hear ONE reported - and documented - case where a meter had failed in the sequence.


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PostPosted: Mon Jan 07, 2008 3:32 pm 

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LaszloZW wrote:
Read the engineering analysis provided via the link in my previous posting. The likeliness of the LED failing at the same time when the breaker opens is improbable. How would you use a "hot-stick" on a 480V MCC cubicle?

If you wish to test for the functioning of the LED's you can always use a battery on the test-leads. The test-measure-test is a leftover from the coil/magnet driven analog meter time and IMO it's necessity is questionable. I just would like to hear ONE reported - and documented - case where a meter had failed in the sequence.


All is well if you see the LED go out when you cut it out .Suppose it trips auto ? Are you sure it was lit in the first place ? I would not put my hand on copper (dead work ) until I have verified all my visible breaks and tested dead at the work location . ABchance makes such a device that can be used with a Hot Stick , Keep in mind it is an induction device and will not read DC (Static Charger)
https://altstore.ewarelive.com/OA_HTML/ibeCCtpSctDspRte.jsp?section=10230&db07_altp=2MFkGYeeyHJleuDzTGNCBhGs:S&db07_altp_pses=db07_altp%3D2MFkGYeeyHJleuDzTGNCBhGs%253AS~


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PostPosted: Mon Jan 07, 2008 3:39 pm 

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Laszlo - have you used this type of scheme or do you know of anyone that has. This seems to be where all this needs to be going. It always seemed like a pain that you have to wear PPE to place the system in an electrically safe condition before you don't wear PPE.


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PostPosted: Mon Jan 07, 2008 3:45 pm 
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Capt Jim wrote:
All is well if you see the LED go out when you cut it out .Suppose it trips auto ? Are you sure it was lit in the first place ? I would not put my hand on copper (dead work ) until I have verified all my visible breaks and tested dead at the work location . ABchance makes such a device that can be used with a Hot Stick , Keep in mind it is an induction device and will not read DC (Static Charger)
https://altstore.ewarelive.com/OA_HTML/ibeCCtpSctDspRte.jsp?section=10230&db07_altp=2MFkGYeeyHJleuDzTGNCBhGs:S&db07_altp_pses=db07_altp%3D2MFkGYeeyHJleuDzTGNCBhGs%253AS~


Jim,

Yes, the built in indicator ONLY facilitates regular LOTO work, which is the vast majority of the requirements. In case of a trip other and additional measures must be taken.


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PostPosted: Mon Jan 07, 2008 3:51 pm 
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C Chord wrote:
Laszlo - have you used this type of scheme or do you know of anyone that has. This seems to be where all this needs to be going. It always seemed like a pain that you have to wear PPE to place the system in an electrically safe condition before you don't wear PPE.


Not in practice yet, but we are in the process of reformulating our enitre approach to LOTO and other "hot work" requirements, but this is definetly one that COULD make life less painless if we can all agree that it indeed does provide the expected safety. I predict that this will start slowly and gain acceptance in the long run. I think the pendulum had swung too far and this could be one device that can swing it back the other way. One thing that we all need to rememeber that this is extra cost, and the only way we can bring the cost down if the volume greatly increases. Then other - perhaps 0ff-shore - manufacturers will bring the price pressure


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PostPosted: Tue Jan 22, 2008 5:06 pm 

Joined: Tue Jan 22, 2008 4:34 pm
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Location: Oklahoma City, Oklahoma
[SIZE="3"][font="Comic Sans MS"][font="Comic Sans MS"]Pardon my newness but what is a "hotstick?"

Chelly [/font][/font][/size] :confused:


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PostPosted: Tue Jan 22, 2008 5:20 pm 
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Chelly wrote:
[SIZE="3"][font="Comic Sans MS"][font="Comic Sans MS"]Pardon my newness but what is a "hotstick?"

Chelly [/font][/font][/size] :confused:


A really sexy comedienne. Ooops....... that would be hotshtick.

It's a long fiberglass pole that is voltage rated to operate medium voltage "hot" equipment, pull live fuses, etc. Open switchyard and lineman tool.

http://www.aplussafety.net/products/store.cfm?CFID=15978134&CFTOKEN=14597017&do=list&d=3053&c=4567

(Would you mind filling in your profile so we don't just respond to a 'Chelly', w/o any clue to who that is?) :)


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PostPosted: Mon Jun 16, 2008 8:53 am 

Joined: Tue Mar 25, 2008 1:00 pm
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Do people really get a hot stick to ensure that the 480V panel they just de-energized is really dead?


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PostPosted: Mon Jun 16, 2008 9:51 am 
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deprico wrote:
Do people really get a hot stick to ensure that the 480V panel they just de-energized is really dead?


Either that or put on gloves, I do both everytime. L-D-L test with non contact and then with contact detector.


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PostPosted: Mon Jun 16, 2008 10:32 am 
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deprico wrote:
Do people really get a hot stick to ensure that the 480V panel they just de-energized is really dead?


Hot stick is for MV work, 1000V and greater, in practical terms 2400V and higher system voltages.

On LV systems one would use V-meter and PPE appropriate both for electrocution and arc-flash hazard.


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