1. Alive & Grounded!! Are your personal grounds really protecting you?
By: Rick Kennerly

2. Overview Reactive Safety Process Evolution of PPG Equipment
ASTM Qualification Testing
Buyer Beware
Changing Viewpoints
No Substitutions
In Service Testing and Maintenance
Final Lesson

3. Reactive Safety Process
We do the best we can with what we know
Near miss or incident occurs
New work methods are developed
Different equipment is utilized
Education and training on the new work methods and equipment is implemented
Near miss or incident occurs again and this process starts all over

4. Evolution of PPG Equipment
We tested for voltage using a crescent wrench and used any wire or chain we could find to lay across conductors
30 years ago we started using lights for testing voltage and welding cable attached to anything we could find for grounding.
20 years ago we started field testing the grounds and realized what we were doing wasn’t the best
Today, we’re still learning how to improve our equipment, education methods, and working procedures to keep both the workers and the public safe as every utility builds and maintains the national electric grid.

5. Qualification Testing
1983 ASTM F855 specified testing needed to qualify equipment to be used
2009 a new table 2 was developed to accomodate higher fault currents
further testing revealed inadequacies with original Table 1 that allowed different methods for rating any particular assembly

6. Qualification Testing ASTM F855 Table 1
Grade
Cable Size
Withstand Rating
Ultimate Rating
15 cyc
30 cyc
60 cyc 1 #2 14 10 18 13 9 2
1/0 21 15 29 3
2/0 27 20 37 26 5
4/0 43 30 59 42 6
250MCM 54 39 70 49 35 7
350MCM 74 98 69 48
Go into detail about the manufacturer being able to choose the lesser of the tests and still rate grade X. Problem being the customer would think a grade 5 clamp could sustain a 59kA fault for 15 cycles but may have only been tested at 43 or worst yet 30 for 30.

7. Qualification Testing ASTM F855 Table 2
Grade
Cable Size
Rating (kA)
X/R=30 1st Cycle Peak
X/R=30 last Cycle Peak
15 Cycles 1 #2 15 41 23 2
1/0 25 65 37 3
2/0 31 84 46 5
4/0 47
126 70 6
250MCM 55
148 82 7
350MCM 68
183
101
Table 2 in fact simplifies the testing and accommodates ground placement within the entire utility from substation to end of line

8. Mechanical Failure – Top Clamp Breaks

9. Mechanical Failure – Bottom Clamp Breaks

10. Mechanical Failure – Top Clamp Breaks

11. Mechanical Failure – Top Clamp Breaks

12. Thermal Failure – Plug Style Ferrule

13. Thermal Failure – Cable Separation

14. Thermal Failure – Cable Fusing at Ferrule

15. Mechanical Failure – Pole Step

16. Mechanical Failure – Pole Stud

17. Buyer Beware Misinterpretation of Table 1 Rigid Bus vs AAC/ACSR
Substations and High X/R
Mechanical and Thermal Energy
If a connector or cable fails to survive thermal or mechanical stress, it may fail electrically before the circuit clears, rendering the ground useless as protection

18. Changing Viewpoints
Testing is forcing manufacturer’s to make better clamps
Molded stud allows for 2 Clamps to be installed in parallel to reduce lifted weight of rated cable assembly
Finer threads allow for greater pressure applied to conductor
Stainless eye screw forces current through upper jaw only and allows smoother operation
Lower Jaw adjustment accommodates bus sizes from 2” to 6” IPS

19. Changing Viewpoints
Substation weld/bolt on studs fail

20. Changing Viewpoints

21. Changing Viewpoints Single versus double ground testing
If you have 1 component that can’t sustain the mechanical forces then adding more assemblies in parallel will not help

22. Changing Viewpoints Single versus double ground testing
If you have 1 component that can’t sustain the mechanical forces then adding more assemblies in parallel will not help 22

23. Changing Viewpoints One 4/0 ground can out perform two 2/0’s

24. Changing Viewpoints

25. Qualification Testing ASTM F855 Table 1
Grade
Cable Size
Withstand Rating
Ultimate Rating
15 cyc
30 cyc
60 cyc 1 #2 14 10 18 13 9 2
1/0 21 15 29 3
2/0 27 20 37 26 5
4/0 43 30 59 42 6
250MCM 54 39 70 49 35 7
350MCM 74 98 69 48
Here again, most utilities believe that if fault currents exceed Grade 5 ratings then they would be ok to use two assemblies…….this is a false interpretation that is also not addressed in the current published ASTM F855 standard

26. Changing Viewpoints
REVIEW test reports for ALL your grounding products (hire professional if help is needed)
Before and After Photos
Wave forms are important
Video of equipment if possible

27. Changing Viewpoints
NEVER use a protective ground above its tested value or outside its tested configuration

28. No Substitutions
Ferrules – #1 Problem because of different dimensions, dies, material, and hardness levels
Cable - #2 Problem because the manufacturing processes are mostly tailored to normal welding cable specs

29. In Service Testing & Maintenance
Circulate alternating current through the cable assembly at its ASTM continuous current rating.
Measure the voltage drop of the entire assembly to determine pass/fail criteria for the assembly.
If a cable heats at it continuous current rating, then the same cable will melt at its ultimate current rating.

32. Visual Inspections
Cracked or broken clamps

33. Visual Inspections
Cracked or poorly crimped ferrules

35. Visual Inspections
Broken strands

36. Visual Inspections Cut or badly mashed or flattened cable
Extensive damage to cable covering
Swollen cable jacket (internal corrosion)
Soft spots in conductor
Blackened strands

37. Grounding Equipment
Cable – What is the difference between grounding cable and welding cable?
Ferrules – Shrouded/Unshrouded Plain/Threaded
Heat Shrink
Clamps – “C”, Duckbill, Flat, Ball Socket, All Angle, Bus, Vice Grip, etc.
Assemblies

38. Cable
TPE jacketed using tight lay construction with no medium between copper strands and insulation

39. Ferrules CDA102 or CDA110 heat treated copper Impact Extrusion process
Roll Threaded not machined
Can be plated
Both shrouded and unshrouded

40. Clamps

41. Final Lesson
Substation Grounds – higher mechanical and thermal energy, rigid structure testing
High current test reporting
Eyescrew Torque requirements
Ferrule to Cable pull out strength
Mechanical versus thermal
Single Ground vs Double Grounds
Regular maintenance inspection and testing
Maintenance Procedures

42. Special Thanks
Pacific Gas & Electric Public Service of New Jersey Entergy Bonneville Power Administration Powertech Labs S&C Labs Travis Pattern & Foundry Trystar Cable Company MLE Engineering Inc.