Transcript 05_Electrical.PPT

Electrical Safing and Planning
Harold L. Bush
D&D Lessons Learned Workshop
June 25-26, 2002
PPPL
June 25-26, 2002
D&D Lessons Learned Workshop
1
Electrical Safing and Planning
• Electrical Safety: An important consideration in
any construction activity- especially one that
involves work in an existing facility. The primary
hazard for experiments such as those at PPPL is
electricity. Fusion machines are electrically
powered devices, with some power system
voltages over 100kV, open bus installations, and
massive energy storage in the way of capacitor
banks and M-G sets. We take electrical safety
very seriously.
June 25-26, 2002
D&D Lessons Learned Workshop
2
Electrical Safing and Planning
We have an excellent electrical safety record
here at PPPL. Research of the last ten years of
safety records at PPPL has revealed no
reportable electrical injuries. However, it
would be interesting to see where electrical
accidents rate in the arena of workplace
fatalities in the U.S (all occupations).
June 25-26, 2002
D&D Lessons Learned Workshop
3
Fatal occupational
injuries by event or
exposure, 1995-2000
Source: U.S. Bureau
of Labor Statistics
June 25-26, 2002
|
Fatalities
_______________________________________
Event or exposure(1)
| 1995-99 | 1999(2) |
2000
| average |
|
| Number | Number | Number | Percent
|
|
|
|
Total..................| 6,165 | 6,054 | 5,915 |
100
|
|
|
|
Transportation incidents.| 2,611 | 2,618 | 2,571 |
43
Highway................| 1,405 | 1,496 | 1,363 |
23
Nonhighway (farm,
|
|
|
|
industrial premises)..|
376 |
352 |
399 |
7
Aircraft...............|
264 |
228 |
280 |
5
Worker struck by a
|
|
|
|
vehicle...............|
380 |
377 |
370 |
6
Water vehicle..........|
106 |
102 |
84 |
1
Rail vehicle...........|
73 |
56 |
71 |
1
|
|
|
|
Assaults and violent acts| 1,085 |
909 |
929 |
16
Homicides..............|
837 |
651 |
677 |
11
Self-inflicted injury..|
216 |
218 |
220 |
4
|
|
|
|
Contact with objects and |
|
|
|
equipment...............|
987 | 1,030 | 1,005 |
17
Struck by object.......|
563 |
585 |
570 |
10
Caught in or compressed|
|
|
|
by equipment or
|
|
|
|
objects...............|
286 |
302 |
294 |
5
Caught in or crushed in|
|
|
|
collapsing materials..|
123 |
129 |
123 |
2
Falls....................|
Fall to lower level....|
Fall on same level.....|
|
Exposure to harmful
|
substances or
|
environments............|
Contact with electric |
current...............|
Exposure to caustic,
|
noxious, or allergenic|
substances............|
Oxygen deficiency ....|
|
Fires and explosions.....|
|
697
620
54
561
308
113
92
202
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
721
634
70
533
280
108
92
216
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
734
659
56
480
256
100
93
177
D&D Lessons Learned Workshop
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
12
11
1
(1) Based on the 1992 BLS
Occupational Injury and Illness
Classification Manual
(2) The BLS news release issued
August 17, 2000, reported a total
of 6,023 fatal work injuries for
calendar year 1999. Since then,an
additional 31 job-related
fatalities were identified,
bringing the total job-related
fatality count for 1999 to 6,054.
8
4
2
2
3
4
Electrical Safing and Planning
• It is interesting to note the the higher
percentages of worker deaths tend to be
associated with everyday activities
(highway deaths, contacts with objects and
equipment). Because many workers at
PPPL deal electrical systems on a daily
basis, we have to be especially vigilant.
June 25-26, 2002
D&D Lessons Learned Workshop
5
Electrical Safing and Planning
• “Don’t” goals:
– No Injuries
– No cuts on energized cables
– Avoid causing accidental interruptions of
building services and the NSTX machine
June 25-26, 2002
D&D Lessons Learned Workshop
6
Electrical Safing and Planning
• Goals
– Ensure that D&D workers can perform their
tasks without the risk of electrical hazards
– Safely disconnect/remove electrical devices and
cabling
– Leave the machine areas safe, code-compliant,
and available for future use
June 25-26, 2002
D&D Lessons Learned Workshop
7
Electrical Safing and Planning
• Challenges Presented by the TFTR D&D
– Not a “green field” D&D job
– Many features of the building infrastructure
were designed and installed coincidental with
experimental systems
– Work to be performed adjacent to an operating
experiment (NSTX) that adopted much of
TFTR’s power/control/cooling systems
June 25-26, 2002
D&D Lessons Learned Workshop
8
Electrical Safing and Planning
• Philosophy and Methodology
Before
June 25-26, 2002
TFTR Test Cell Basement
D&D Lessons Learned Workshop
After
9
Electrical Safing and Planning
• Philosophy and Methodology
– Shut down systems as required- no wholesale
AC power shutoff
– Disconnect and remove electrical equipment on
a “system by system” basis
– Identify and protect wiring/devices that must
remain post D&D
– Develop a method to safely perform “prompt”
removals on an as-needed basis to support the
project
June 25-26, 2002
D&D Lessons Learned Workshop
10
Electrical Safing and Planning
• Philosophy and Methodology (cont’d)
– Test immediately prior to cutting- however, treat
all cable cuts as “live”
– Toward the end of the effort, switch from a “half
full” to a “half empty” perspective in the
identification and removal of electrical items
– Final items to be removed are the tray cables
previously cut during system removals
June 25-26, 2002
D&D Lessons Learned Workshop
11
Electrical Safing and Planning
June 25-26, 2002
D&D Lessons Learned Workshop
12
Electrical Safing and Planning
June 25-26, 2002
D&D Lessons Learned Workshop
13
Electrical Safing and Planning
June 25-26, 2002
D&D Lessons Learned Workshop
14
Electrical Safing and Planning
• Examples of Cable “Pigtails” Following System Removal
June 25-26, 2002
D&D Lessons Learned Workshop
15
Electrical Safing and Planning
• Useful tools and techniques:
– Tools
•Non-contact ac voltage indicator- not all
are alike. It is well worth the expense to
purchase and test a number of them.
•Battery powered cable cutter- useful in
cutting multiple cables (such as in bulk
tray removals) or large cables (up to 750
MCM). Also provides additional control
and safety since operator is not straining to
slice through cables. One handed
operation- very useful when on a ladder.
June 25-26, 2002
D&D Lessons Learned Workshop
16
Electrical Safing and Planning
• Useful tools and techniques (Cont’d):
– Techniques:
• Removal of cabling and conduits to the tray system
and leaving the tray cable removals to last worked
extremely well. In the end, we were able to safely
remove thousands of cables from tray systems and
leave behind the handful which were necessary for
NSTX machine operation.
June 25-26, 2002
D&D Lessons Learned Workshop
17
Electrical Safing and Planning
• Useful tools and techniques (Cont’d):
– Techniques (Cont’d)
• Safety and productivity are enhanced by employing
the same individuals to perform electrical removals
for the duration of the job. Using a consistent
procedure format also helps enable electricians to
better become the “last line of defense”- they can
more easily spot something that “doesn’t look right”
because they are experienced and comfortable with
the work flow in a typical electrical safing and
removal procedure.
June 25-26, 2002
D&D Lessons Learned Workshop
18
Electrical Safing and Planning
• Lessons Learned “The Hard Way”
– Non-contact voltage sniffers do not detect dc.
If you employ dc (battery) systems for control
power, you will inevitably, in your cable
removals, discover an energized dc cable (and
in a most impressive manner). That is why all
cable cuts are treated as if you are cutting a live
cable- because, despite your best efforts at
shutdown and disconnection of power sources,
sometimes it happens!
June 25-26, 2002
D&D Lessons Learned Workshop
19
Electrical Safing and Planning
• Lessons Learned “The Hard Way” (Cont’d)
– Removal work goes MUCH faster than
installation work. Planning and procedure
preparation require at least twice as much labor
as the field electrician effort. It takes some
doing to keep the electricians supplied with
work!
June 25-26, 2002
D&D Lessons Learned Workshop
20
Electrical Safing and Planning
• Lessons Learned “The Hard Way” (Cont’d)
– NFPA 70E: PPPL is a leader in the application of this
important electrical safety standard, which has recently
incorporated protection from electrical arc-flash events.
A significant feature of this standard is a basic “no hot
work” philosophy, requiring significant changes to the
planning and execution of electrical work on existing
systems. Tasks historically performed in energized
panels, such as adding or removing a wire from a
breaker, now require a panel shutdown. Additional
planning and electrician resources are necessary to
coordinate these outages, and must be accounted for
when scheduling and budgeting the work.
June 25-26, 2002
D&D Lessons Learned Workshop
21
Electrical Safing and Planning
Required PPE for NFPA 70E (to investigate in energized Lighting Panel)
June 25-26, 2002
D&D Lessons Learned Workshop
22
Electrical Safing and Planning
• Summary- Electrical Scorecard thus far
(knock wood):
– Reportable events, injuries
0
– Energized cables discovered
with indicating devices
Few
– Energized cables discovered
with cable cutters
1
– Cables cut that should have not been 1
June 25-26, 2002
D&D Lessons Learned Workshop
23