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Mill Creek, Washington

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Mill Creek, Washington

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    2. 2 Ground Faults, Galvanic Current, and Stray Current in a Marina Environment NWMTA November 1, 2006 Presented by Larry Boyer, P.E.

    3. 3 NFPA 303 Section 3.21.1 Visual Inspection

    4. 4

    5. 5

    6. 6

    7. 7 Goals Understanding basic marina electrical terms. Causes of marina electrical problems. What can I do to protect my marina?

    8. 8 Ground Fault An unintentional electrical connection from a hot A.C. source to the grounding system.

    9. 9 Undetected Ground Fault An unintentional electrical connection between an energized A.C. source and the grounding system, which causes a fault current to flow at a level too low to trip a fuse or circuit breaker.

    10. 10 Electric Shock Drowning .015 A (15ma) Paralysis

    11. 11 Undetected Ground Fault Electric shock injury or a fire could result.

    12. 12 A Typical Monitoring Arrangement

    13. 13

    14. 14 Galvanic Current A galvanic cell is formed by dissimilar metals connected together and placed in an electrolyte.

    15. 15 Galvanic Cell - Battery All boats connected to AC shore power are part of galvanic cell.

    16. 16 Galvanic Isolator

    17. 17 A Consequence of Being Part of the Marina Bonding System

    18. 18 Stray Current Similar to galvanic corrosion, but with the addition of a battery, damage is greatly accelerated. Damage may extend to nearby boats.

    19. 19 STRAY Current Corrosion Test Bronze Thru-Hull Fitting in Seawater: Subjected to .62 AMPS AC current for 1,000 hours No measurable damage. Subjected to .5 AMPS DC current for 72 hours Complete component failure. Conclusion: In this test, STRAY AC current is not a measurable factor in induced corrosion.

    20. 20 Questions? Path Engineers, LLC Larry Boyer General Manager 425-481-7735

    21. 21 Summary

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