Grounding of Overhead Crane Systems

Grounding of Overhead Crane Systems

Grounding of Overhead Crane Systems
Grounding is a critical part of a safe installation.

In 1995, the Bureau of Labor Statistics reported that electrocutions accounted for 6% of all worker deaths. The most common OSHA electrical violation is the improper grounding of equipment and circuitry. It routinely hits the top 25 in terms of OSHA citations.

Our customer service group periodically receives calls with questions concerning grounding requirements for overhead cranes. Over the years it has been customary to ground through the crane and trolley wheels, through the crane girders and runways to the building steel.

In the 2005 edition of ANSI/NFPA 70 National Electric Code grounding requirements changed.  Article 610, Cranes and Hoists, Section 610.61 Grounding clearly states, “The trolley frame and bridge frame shall not be considered electrically grounded through the bridge and trolley wheels and its respective tracks.  A separate bonding conductor shall be provided.” The terms “shall and shall not” make the fourth conductor for ground mandatory. It does not matter if the electrification is festoon cable or insulated conductor bar.

Question: “My hoist will be running on a jib or a monorail. Do I still have to run a ground?”

The simple answer is, “Yes!”  The scope of Section 610.1  is quite clear; it covers cranes, monorail hoists, hoists and all runways.  ANSI/ASME B30 Safety Standards define cranes for overhead hoists. In essence, if a hoist is supported by an overhead structure such as a monorail, jib, bridge, or gantry, it is a crane. Whether the crane is portable, like a roll around gantry, or a permanent installation, it is a crane and needs a separate conductor for ground.

Grounding is a critical part of a safe installation.  More and more cranes are equipped with electronics; remote controls, variable frequency, electronic monitoring devices, etc. These need grounding for their protection. Current follows the path of least resistance.  If a short to ground exists, do you want the crane operator to be the ground?  All it takes is one hand on the lower block and the circuit is complete.  Be safe, run the ground.

This blog post was written by Larry Lynn, former Product Trainer for Columbus McKinnon Corporation.

20 Replies to “Grounding of Overhead Crane Systems”

  1. I got helpful information on grounding of overhead crane since I knew little about it before. Looking forward to your new sharing post here.

  2. I would like to sell a yellsix tun Crean. It hangs on the trolley and rools on i beemib. It looks like a giant went with an exam baffle sounds very loud like a jack hammer.

  3. Hello Jose,
    Thank you for your question. This requirement does not apply to equipment in place prior to the rule change in 2005. The change in NEC 610.1 came about in 2005 and addresses “New Installations.”
    Tom

  4. Tom
    I am on the same as Bill our crane was installed in 2002 but in our last pm service we got a new tech this was his first time and he said that we need to upgrade he give me a price of $4.430.00 I hope you take the time and respond to my question

    Thank You
    Jose Castaneda

  5. When completely replacing a 3 bar system on a runway and crane that was installed prior to 2005 do I have to install a 4 bar system?

  6. Hello Camilo,
    Thank you for your comment. Could you please provide us more information, such as:

    1) Is the gantry powered? You state that it is operated by hand.
    2) Does it have a powered hoist and trolley?
    3) Does the gantry run on a crane rail?

    Looking forward to your response,
    Tom

  7. Hi, goodmorning everybody

    There is a hand-operated gantry crane (2t) that moves by wheels over a concrete floor inside to a hangar. This gantry crane is used to lift engine parts during maintenance operations. So the question is: The gantry crane needs to be grounded? bearing in mind that is a portable equipment like a supermarket car?

  8. Hello Scott,
    In the 2005 edition of ANSI/NFPA 70 National Electric Code grounding requirements changed. Article 610, Cranes and Hoists, Section 610.61 Grounding clearly states, “The trolley frame and bridge frame shall not be considered electrically grounded through the bridge and trolley wheels and its respective tracks. A separate bonding conductor shall be provided.” The terms “shall and shall not” make the fourth conductor for ground mandatory. It does not matter if the electrification is festoon cable or insulated conductor bar.
    Peter

  9. Our crane operators have a concern that the collector that rides against the ground bar may become worn and inoperable as a permanent ground between crane inspection points without anyone knowing. What would NEC or OSHA thoughts be on considering the trolley wheel and bridge as a secondary ground to cover a short time period between inspections?

  10. Hi Matt,
    In response to the question, “Does OSHA require the separate ground conductor of a crane to be a different color than that of the other conductors..?” –
    OSHA states, “All cranes must comply with OSHA 1910.304(a)(1)(i) and (a)(l)(ii), which requires that all equipment grounding conductors be identifiable and distinguishable from all other conductors…”
    To answer your question, the ground bar does not have to be green, but it must be distinguishable as ground.
    Tom

  11. Is it required that the ground power bar rail be Green to signify that it is the ground bar in the power bar system?

  12. Hello Rodney,

    Thank you for writing us and sorry for the delay. OSHA 1910.179 has not been updated in many years. 1910.179(g) (1) (i) addresses crane wiring by referring to 1910 Sub Part S. You can find this by clicking the osha.gov link provided below:

    https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9881

    The most current version of ASME B30.2 was revised 07/29/11. Para 2-1.13.2 refers us to Article 610 of ANSI/NFPA No. 70, National Electrical Code.

    The information in the following LinkedIn Group discussion is very informative and covers exactly what most folks want to know about grounding. You will need to become a member of the group to participate. The discussion referenced in the below link pertains specifically to crane grounding. I believe you’ll find the information very useful.

    http://lnkd.in/9w3V8T?trk=groups_most_popular-0-b-shrttl&goback=%2Egna_2264889

    Kind regards,
    Tom

  13. I see the reference to the NEC 610.1 and see the notations addressing “New Installations”
    Can you give me the most up to date OSHA and ASME B30.2 rules on grounding?

  14. Dear Mark,
    This is an age old question for which everyone has an opinion. I find nothing in the regulations or standards that prevents the extension of the existing system. I am however not an expert on the National Electrical Code. Also, each state, city or township can have specific requirements.

    A better route might be to jump in on the LinkedIn conversation concerning grounding at the link below. The opinions expressed from local experts in the group could be very informative. http://owl.li/r6bMA

    Good luck!
    Tom

  15. Can uninsulated runway conductors be added onto when extending a runway or do you have to upgrade the entire lenght of the runway to have insulated conductors?

    Thanks,

    Mark

  16. Hi Bill,
    This requirement does not apply to equipment in place prior to the rule change in 2005. The change in NEC 610.1 came about in 2005 and addresses “New Installations”.
    Thank you for your question.
    Tom

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