1. IEC 61230 IEC 61230 Standard defines:
Test duration
Test method and configuration specific
Peak current factor
Tolerances
IEC Standard does not define:
Specified current test values
Pass / Fail rated values

2. IEC 35kA Rating IEC 61230 35kA Rated values:
J configuration test setup
Rated current – 35kA
Test duration – 17 Cycles
Peak current factor – 2.6
AC component of test – 115%
Test 115% kA
1st cycle peak current – 104.7kA

3. IEC 40kA Rating IEC 61230 40kA Rated values:
J configuration test setup
Rated current – 40kA
Test duration – 17 Cycles
Peak current factor – 2.6
AC component of test – 115%
Test 115% - 46kA
1st cycle peak current – 119.6kA

4. IEC 55kA Rating IEC 61230 55kA Rated values:
J configuration test setup
Rated current – 55kA
Test duration – 17 Cycles
Peak current factor – 2.6
AC component of test – 115%
Test 115% - 63kA
1st cycle peak current – 164.5kA

5. ASTM F855 ASTM F855 Standard defines:
Test duration
Specific test current values
Defined X/R values
Cable test lengths
Pass / Fail ratings
ASTM F855 Standard does not define:
Tolerances

6. ASTM F855 Grade 5 Rating ASTM F855 Grade 5 rated values:
J configuration test setup
Conductor length – defined at 10ft
Test duration – 15 cycles / 30 cycles
X/R – 1.8
Withstand rated 15 cycles – 43kA
Ultimate rated 15 cycles – 59kA
Withstand rated 30 cycles – 30kA
Ultimate rated 30 cycles – 42kA

7. ASTM F855 Grade 6 Rating ASTM F855 Grade 6 rated values:
J configuration test setup
Conductor length – defined at 10ft
Test duration – 15 cycles / 30 cycles
X/R – 1.8
Withstand rated 15 cycles – 54kA
Ultimate rated 15 cycles – 70kA
Withstand rated 30 cycles – 39kA
Ultimate rated 30 cycles – 49kA

8. ASTM F855 Grade 5H Rating ASTM F855 Grade 5H rated values:
J configuration test setup
Conductor length – defined at 10ft
Rated current – 47kA
Test duration – 15 cycles
X/R – 30
1st cycle peak current factor – 2.69
1st cycle peak current – 126kA
Last cycle peak current – 70kA

9. ASTM F855 Grade 7H Rating ASTM F855 Grade 7H rated values:
J configuration test setup
Conductor length – defined at 10ft
Rated current – 68kA
Test duration – 15 Cycles
X/R – 30
1st cycle peak current factor – 2.69
1st cycle peak current – 183kA
Last cycle peak current – 101kA

10. IEC vs ASTM Summary ASTM F855 IEC 61230 Grade 5, 6, 5H, & 7H Ratings
35, 40, & 55kA Ratings
Test Duration – 17 cycles
Peak Current Factor – 2.6
1st Cycle Peak Current
35kA – 104.6kA
40kA – 119.6kA
55kA – 164.5kA
No critical pass / fail current value.
Test Duration – 15 / 30 cycles
X/R – 30 for Grade 5H & 7H
Withstand Test Current:
Grade 5 – 15 Cycles
Grade 5 – 30 Cycles
Grade 6 – 15 Cycles
Grade 6 – 30 Cycles
Grade 5H – 47kA Rated
Grade 5H – 126kA Peak 1st Cycle
Grade 7H – 68kA Rated
Grade 7H – 183kA Peak 1st Cycle
Must meet critical current levels above to be certified.

11. X/R Ratio Impedance Triangle
X/R is a ratio determined by the system reactance “X” divided by the system resistance “R” looking back towards the power source at the time of a fault.
X/R determines the DC component of a ground fault and will decay quickly to only AC symmetrical component of fault.
Full DC offset occurs at the time when the DC component current is equal to the initial peak value of the AC current.
A higher X/R ratio will lead to a longer DC offset where as a small X/R ration will lead to a rapid DC offset.
High X/R ratios lead to more severe and damaging ground faults versus small ratios.
High X/R ratios are useful for testing purposes to push equipment to its ultimate electrical and mechanical ratings and capabilities.
Impedance Triangle
Apparent Power (kVA)
Reactive Power (kVARS)
Real Power (kW)

12. IEC Ground Fault Testing
Resulting waveform of 35kA ground fault test using high X/R ratio with peak current at kA. Full DC offset occurs at the 10th cycle of ground fault.

13. IEC Duckbill Testing Duckbill Test Shot Duckbill Slow Motion Test Shot
Duckbill Clamp certified to ASTM F855 5H and IEC kA Ratings
1st Cycle Peak Current – 104kA, Symmetrical Current 40.3kA
Duckbill Test Shot
Duckbill Slow Motion Test Shot
Duckbill Test Shot w/ Ball Stud Failure
Slow Motion Failure of Ball Stud
Solution to failure – 25mm Ball Stud torque rating too low for duckbill application. 30mm Ball Stud torque rating sufficient for use with Duckbill Clamp on ground end.

14. IEC 30mm Ball Stud Clamp Testing
30mm Ball Stud Clamp tested to IEC kA Ratings
1st Cycle Peak Current – 164kA, Symmetrical Current 63kA
30mm Ball Stud Clamp Test Shot
30mm Ball Stud Clamp Slow Motion
30mm Ball Stud Clamp Heating Failure
30mm Ball Stud Clamp Heating Failure Slow Motion
Solution to failure – Thread inside of Ball Clamp to to increase surface area at bolt to clamp connection and to reduce arcing at bolt.

15. IEC C-Clamp Testing 4” C-Clamp Test Shot
4” C-Clamp tested to IEC kA Ratings
1st Cycle Peak Current – 119kA, Symmetrical Current 46kA
4” C-Clamp Test Shot
4” C-Clamp Slow Motion Test Shot
4” C-Clamp Test Shot w/ Ferrule Failure
4” C-Clamp Slow Motion Failure of Ferrule
Solution to failure – Failure was due to high current level and ferrule to clamp connection. Solution to failure is to change to a threaded fitting connecting the ferrule to clamp.

16. Safety First
Fun Fact :
In just 0.25 seconds, the temperature of the insulating jacket on a ground set reaches 290°F for a 35kA phase to ground fault with a ground set resistance of 1mΩ or less.