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November 22, 2006 A Prism Business Media Publication Vol. II No. 22

Holidays and Maintenance

Electrical Troubleshooting Quiz

Repairs on Critical Equipment

NEC at the Facility

OSHA and Holiday Maintenance

Answer to Electrical Troubleshooting Quiz


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MRO Insider addresses topics such as:

  • Working with management and supervision
  • National Electrical Code® on the production floor
  • Safety procedures and programs
  • Troubleshooting techniques
  • Equipment maintenance and testing tips
  • Managing motors and generators
  • Trends in training and education
  • Managing energy use

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    Holidays and Maintenance
    While November and December are busy months for holidays, they are also busy months for the typical maintenance organization. For many of these organizations, one problem is that each year seems to hold the same "surprises" as previous years.

    If this sounds familiar, assign someone to track this year's problems in some kind of software -- such as a computerized maintenance management system or spreadsheet. Failing that, use pen and paper! Then, form an action plan to eliminate those problems. You are more likely to make progress by focusing on the three most irritating ones than trying to solve all of them at once.

    Here's a partial list of typical "annual been there, done that" problems. Can you identify the solutions that would work in your facility?

    • Delays due to locating and stringing cords for temporary power.
    • Security and access delays for contractors.
    • Uncoordinated work among crews.
    • Only "Jim" knows how to program machines X, Y, and Z -- and we're all waiting on him.
    • Nobody had the key to the... (tool crib, store room, bathroom).
    • Battery was dead in scissor lift.
    • Insufficient (tools, parts, materials, filters) on hand.
    • Expired test equipment calibrations.
    • Breaker setting calculations (or other engineering information) not available.

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    Electrical Troubleshooting Quiz
    A critical production line stopped because the main drive motor failed. After replacing the motor and restarting the line, you try to determine why that motor failed. You turn the output shaft by hand and hear a grinding sound. A closer inspection reveals dried grease on the bearings. Was this probably because the lubrication interval was too long?

    The answer to this question appears at the end of this newsletter.

    Repairs on Critical Equipment
    Does your critical equipment seem to incur downtime more often than non-critical equipment? You may not be imagining this. You may be experiencing the "critical equipment vicious cycle." Here's the typical pattern:

    1. Critical equipment goes down.
    2. Maintenance tech arrives promptly, begins troubleshooting.
    3. Production supervisor was apparently expecting Superman.
    4. Someone pesters the tech every two minutes with questions, demands, or suggestions.
    5. The tech does a band-aid fix, just to get the equipment running again until proper troubleshooting can be completed under better circumstances.
    6. Now production says, "If it's working, don't fix it."
    7. The root cause doesn't get identified, much less fixed. Consequently, the machine breaks down prematurely.
    What typically happens when a motor fails? Maintenance replaces the motor, but doesn't determine the failure mode. Yet, motors fail for a reason. If that reason isn't addressed, the replacement will probably fail for that same reason.

    It is normally not as valuable to get critical equipment back online immediately as it is to get it back online properly repaired. Normally, the cost of an extra downtime incident is far higher than any revenue "protected" by incomplete troubleshooting and inadequate repair.

    Assess your situation and communicate the value of the proper level of repair to all affected parties. You can bolster your case by using actual revenue losses per downtime incident.

    Beware - Arc
    Flash Hazard

    Pin and sleeve plugs & receptacles can be dangerous if operated under load. To prevent accidents install Decontactor Series switch rated plugs and receptacles. They are a UL rated plug, receptacle and disconnect switch in one device. 100 kA short circuit ratings protect users in fault conditions. Inquire about our free trial program.
    Meltric Corporation, call 800-433-7642,

    NEC at the Facility
    The typical facility undergoes many changes over time, leading to "add on syndrome." You've seen this -- too much crammed into existing cabinets, making maintenance difficult. This situation violates 312.7, which prohibits overcrowding of cabinets and cutout boxes [312.7].

    OSHA and Holiday Maintenance
    During holiday maintenance, several conditions conspire to raise the risk of injury:
    • Due to the time limitations, people are tempted to take shortcuts to complete projects in the allotted time.
    • With most personnel gone, it's easy to adopt an informal attitude. "Nobody is here to use this, so why waste time locking it out?"
    • Holiday schedules can reduce alertness. During holidays, people tend to stay up later and become sleep-deprived. The Sleep Institute has found that a person who is 20% sleep-deprived has the mental acuity of someone who is drunk. This is not an easy problem to manage, but making individuals aware of it ahead of time may help save a life during Thanksgiving or Christmas.
    Think of other safety compromises that may occur during holidays, and talk with your crews about them. See what suggestions they have. Actively work to prevent adding OSHA incident reports to your holiday schedule.

    Motor Starter Contacts
    Quality, low-cost electrical contacts for industrial motor starters & contactors. Repco replacements for Allen-Bradley, ABB, Clark, Cutler-Hammer, GE, Hubbell, Siemens, Square D & Westinghouse. Also for GE 100/200/300, CR7006, CR2800, CR2810, CR7 IEC and DS303 series. Large inventory & application help.

    Quiz Answers
    Answer to Electrical Troubleshooting Quiz
    Grease consists of a carrier and a lubricant. The carrier is the medium that holds the lubricant in place. If the lubricant is squeezed out by pressure or evaporated out by heat, the grease "dries up." Most likely, some condition caused excess heat in that bearing.

    If you don't have a thermal history on that bearing, can you investigate the cause? Yes. You may be thinking, "I'd want to monitor the bearing temperatures on the new motor. The recent failure is a good cost justification for installing such a monitor." That's a good thought, but there's a catch. A bearing high temperature alarm will tell you there's a problem, but it won't tell you what it is. You must determine the source of that heating.

    Rather than wait for the new motor to exhibit excess bearing heat, work now to identify and eliminate all causes of it. There may be several at once, so don't stop just because you find one. Begin with these three problems:

    1. Voltage imbalance. Even a small imbalance causes a large rise in motor temperature. Just because the bearing grease cooked out first doesn't mean the imbalance isn't damaging the winding insulation. Consider putting a critical motor on its own branch or feeder circuit.
    2. Misalignment. Even a small misalignment can raise bearing temperature, especially with heavy loads. If the motor is critical, it may be wise to hire a specialist to align it with the right tools and techniques.
    3. Bonding. Current flows in inverse proportion to the resistance of the paths presented to it. In the absence of a good bond, bearings make a relatively low-resistance path. See the Article 100 definition of bonding.
    There are many other possible causes, but these three are common -- and fairly easy to resolve.

    Show & Events

    Check out this list of gems, all free of charge in the "On-Demand Library and Viewing Room" across from Conference Room A within the virtual trade show:
    • Preparing a Claim: Bolstering Your Case Through Good Project Management
    • Harmonics: Causes, Symptoms, and Remediation Techniques
    • Power Outages: Preventive Electrical Designs and Product Solutions
    • Electrical Power Engineering: Industry Shortcomings and Possible Solutions
    • MV Cable Basics: Construction, Testing, Ground Fault Coordination
    • Ten Trends That Will Shock the Electrical Market
    • Good Project Management: Enhancing the Bottom Line
    • Insulation Resistance Testing
    • Short Term, Long Term Energy Storage Methods for Standby Power Systems
    • 2007 Construction Market Forecast

    Before accessing the archives, make sure you visit the 2006 EC&M e-TradeShow, a year long virtual business event. In addition to attending live activities at conference sessions scheduled throughout the year, you can meet with exhibitors in virtual exhibit halls. Free access and all the information you need are available at

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