Jim Hill Dow Chemical

1
Jim Hill Dow Chemical

• Chlor-Alkali T-760 Incident

2
The Job

• Electrically Clear R-44 Rectifier
• Re-commission R-44
• perform needed tests
• connect low voltage source (480 VAC)
• reduced voltage test for rectifier components
• Human resources
• 2 very experienced electrical engineers
• 2 very experienced electricians (Sam Mike)
• Factory technician

3
138 KV (open tagged)
OCB
Tap Changer
T-760
15 KV
800 VDC (open tagged)
DC Cell Switch
Chlorine Cells
4
T-760
R-44
5
The Scope Change

• T-760 tap changer problem
• Position indicator not working
• Ratio test needed
• Connected 120 VAC to the 138 kV bushings
• 3 conductor 16 AWG cable
• Change taps and measure the ratio
• Reset the tap position indicator
• Job complete
• Remove wires (Mike) go to lunch

6
480 Volt Supply
138 KV (open tagged)
Test wires connected here Disconnected
after completion of ratio test
OCB
120 volts
480/120 Transformer
Tap Changer
T-760
15 KV
800 VDC (open tagged)
DC Cell Switch
Chlorine Cells
7
T-760
R-44
8
After Lunch

• Started low voltage testing R-44 Rectifier
• Dow engineer factory technician

9
480 Volt Supply
138 KV (open tagged)
OCB
Tap Changer
T-760
480 Volts
15 KV
800 VDC (open tagged)
DC Cell Switch
Chlorine Cells
10
After Lunch

• Mike went to work on another job
• Sam rejoined crew and was looking for a task
• Could not work in rectifier - testing in progress
  
• Decided to remove copper strands from T-760

11
T-760
R-44
12
The Shock

• Climbed up on top of transformer
• Tied off with safety harness
• Reached up to remove copper strands

• Bushing energized with about 2,770 VAC
• Fell, scraped back on oil piping
• Felt like
• Small second degree burn on finger

13
480 Volt Supply
138 KV (open tagged)
OCB
Test wires connected here
Tap Changer
T-760
480 Volts
15 KV
800 VDC (open tagged)
DC Cell Switch
Chlorine Cells
14
Contributing Factors

• Changed personnel in mid-job
• Job scope changed
• No written procedure for work
• No testing standards for work
• Electrician had worked two weeks with no days off
• Electrician recently divorced

15
Key Safe Work Practices

• Use GFCIs
• First choice - DE-ENERGIZE!
• Establish minimum approach distance
• Dress for the task - clothing and jewelry,
  beliefs
• Use safety grounds
• Use work zones

• Hold effective job briefings
• Test before you touch

16
Job Briefing (70E 2-3.1.6 of Part II)

• The person-in-charge shall conduct a job briefing
  before starting each job.
• At least one job briefing shall be conducted
  before the start of the first job of the day or
  shift. Additional job briefings shall be held if
  changes occur during the course of the work that
  could affect personnel safety.
• A more extensive discussion shall be conducted
  if
• (a) The work is complicated or particularly
  hazardous, or
• (b) The employee cannot be expected to recognize
  and
• avoid the hazards involved in the job.

DRC
17
JOB BRIEFING

• The job briefing shall cover at least the
  following subjects
• Hazards associated with the job
• Work procedures involved
• Special precautions
• Energy source controls
• Personal protective equipment requirements

DRC
18
It only takes a second and one careless act...
19
Prevention!

• Set up a work zone
• Conduct a job briefing before the start of each
  job
• Include the safety issues
• STOP and have another job briefing
• When changes occur during the job
• Before a new person is permitted to enter the
  work zone

20
Prevention!

• Limit access to work zone
• Allow only people involved in the job inside
• no matter who they are or how qualified they may
  be
• Special attention
• Alternative source of energy introduced into a
  CLEARED circuit!

21
(No Transcript)
22
(No Transcript)