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I Thought It Was Dead

Posted By Philip Cox, Monday, May 01, 2000
Updated: Monday, February 11, 2013

Assuming electrical circuits or equipment is dead or de energized can be a costly mistake. Phrases such as "I thought it was dead” have been used following an incident where an electrical shock or electrocution occurred. It pays to check it out. Every electrician who has worked for any length of time in the trade understands what can happen when a mistake occurs during work on energized or live parts of an electrical system. Electricians are taught in safety training classes to test the circuit to see if it is energized and to turn the power off before working on electrical equipment. Additional safety practices stipulate that the circuit should be locked out so that it cannot be inadvertently re-energized. For those situations where power cannot be shut off, proper safety equipment and procedures are to be used.

How many times have electricians intentionally worked on energized electrical systems when they easily could have been turned off? How often is safety equipment used when electricians have to work circuits hot? Experience has taught that many workers in the electrical construction field knowingly take risks by working on electrical equipment or circuits while they are energized when they could have readily been de-energized. When asked about it, a variety of answers are given as to why they do it. Excuses range from "I didn’t have time to go turn it off” to "If you can’t work it hot, you don’t need to be in the field.” Unfortunately, these types of attitudes are all to prevalent in the industry. An element of pride and good workmanship is the knowledge ability to work safely without taking risks that can have life long lasting effects. Electric shock and electrocution can ruin not only the lives of the individual(s) involved in the incident, but has devastating effects on families.

It is worth the time to go to the toolbox or truck to get a volt meter to verify that equipment to be worked on is not energized. It is a good practice to verify that the voltage tester is working. Test it on a known live circuit before testing the circuit being worked on. Relying on what appears to be or on someone’s word is dangerous. On one occasion where portable stage equipment was being connected to a weatherproof fusible 200-amp switch, the electrician making the connection did not have a volt meter handy and proceeded to connect the portable cable to the bottom lugs of the switch. Two raceways emerged from the ground and entered the switch from the bottom. A set of ungrounded conductors from one raceway connected to the top lugs of the switch and the conductors in the other raceway connected to the bottom lugs. The electrician opened the switch and began the process of connecting the portable cable to the bottom lugs. During the process, the electrician inserted the wrench in the slot and began loosening the hex screw in the wire terminal. As his hand brushed lightly against the side of the switch enclosure, he received an unpleasant shock. After checking, it was found that the switch was fed from the bottom, resulting in the lugs being worked on and the open blades being energized. The individual made an incorrect assumption that because the switch was supposed to be fed from the top lugs that it had actually been installed correctly. It could have been a severe lesson to learn had the metal wrench come in contact with the metal enclosure or if the individual made good contact with a grounded object while holding the wrench to the lug.

Another assumption was made by an individual that could have resulted in a serious injury or a fatality. He was attempting to find out why a lighting fixture installed in a suspended ceiling of an office building would not work properly. The circuit feeding the fixture was enclosed in electrical metallic tubing and was connected to the fixture junction box by a compression-type connector. The EMT was secured to steel bar joists above the suspended ceiling. The electrician climbed a ladder and removed a lay-in ceiling tile in order to access the fixture and grasped the steel bar-joist with one hand to steady himself. With the other hand he loosened the screws on the junction box with a screwdriver and started to remove the cover. Upon contact with the fixture junction box, he received a shock running through both arms and across his chest. Fortunately, he was able to quickly remove his hand from the fixture housing and was stable enough to maintain his balance on the ladder. Upon investigation, it was found that the fixture junction box and housing was energized because the ungrounded hot conductor had separated from the wire connector and was in contact with the side of the junction box. The fault current path had been interrupted because an EMT connector was loose and did not make good contact with the metal raceway. Without a reliable path for fault current, the overcurrent protective device did not operate and the fixture housing remained at a potential of 120 volts to ground. No attempt was made to first disconnect power from the circuit before working on the fixture.

One electrician related a story of an installation where it was assumed that because a circuit breaker handle was in the off position, the circuit was not energized. Two individuals were installing a circuit for an electric range in an existing dwelling. The cable was run and because of the pressure to complete the job and get to another location, one electrician began connecting the cable to a receptacle at the range location. The other electrician began making the connection to the circuit breaker at the panelboard. After working the circuit breaker handle and leaving it in the off position, he installed it in the panelboard and began connecting the conductors. Upon connecting the conductors to the circuit breaker, the worker installing the range receptacle received a painful shock. It was discovered that the circuit breaker had been left unprotected in the back of a work truck and had been exposed to rain. The moisture had corroded the circuit breaker contacts and they remained closed even after the handle had been turned to the "off” position.

There is no substitute for knowing how to safely work with electricity and closely following safety procedures. It is not a test of courage to intentionally touch live parts or to work equipment hot. Working circuits hot does not create heroes. Heroes are made when they demonstrate wisdom in avoiding hazards where possible. It sometimes helps to bring the point home by listening to those who have been severely shocked by making contact with live parts or who were badly burned as a result of the flash of an electrical fault. It definitely pays to check out the equipment to make sure it is not energized before working on it.


Read more by Philip Cox

Tags:  Featured  May-June 2000 

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