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Electrical circuits should always be de-energized before repairing or replacing any electrical component or wiring. De-energize at the system’s disconnect and then follow standard lock-out/tag-out procedures. Lock out the circuit by placing a padlock on the disconnect switch, which will prevent anyone from accidentally energizing the circuit while you are working on it. Place a tag on the disconnect switch so any other building or maintenance personnel knows the system is being serviced and who de-energized it. When following the basic lock-out/tag-out procedure, always follow the guidelines set forth by the agency having jurisdiction.
Before working on any electrical circuit, always verify with a voltmeter that the circuit is truly de-energized. The disconnect switch may appear to have de-energized the circuit, but there may be an internal defect in the switch or someone may have bypassed the switch which may cause one or more of the hot legs to remain energized.
Technicians should always work with insulated tools and only use electrical powered tools that are properly grounded. Also, always use the right gauge extension cord sized by the maximum amperage draw of the equipment and tools to be powered and one with a GFCI outlet. Also, before using any extension cord, always check for and repair any frayed or damaged wiring. Never use a damaged or worn extension cord.
Capacitors have the ability to store an electrical charge. Because of this a technician should always discharge a capacitor before handling or checking it. A capacitor can be safely discharged using a 20,000 ohm, 5-watt resistor with an insulated pair of pliers. Some start capacitors have a bleed resistor across the terminals designed to discharge the capacitor. It is still a good practice to discharge these capacitors with your own resistor. The resistor on the capacitor may be electrically open and may not have discharged the capacitor.
Care should be taken when examining the terminals of a compressor. It is possible for a weakened terminal to blow out and cause injury to a service technician. If the terminals are weakened due to some system problem, the refrigerant pressure within the compressor can cause one or more of the terminals to blowout.
Never bypass a fuse/circuit breaker or replace one with one rated higher than the original. They are designed to open the circuit when a fault occurs. Bypassing this protection is simply wrong and can cause serious injury to you or another technician.
Following these and other job specific safety precautions will help to prevent some of the many careless electrical injuries experienced by many refrigeration technicians. Sometimes working safely takes time, but it is an investment in your well-being and should never be short cut or disregarded.
Publication date: 06/07/2010