I interpret The adage “A little knowledge is a dangerous thing”to mean just a small amount of knowledge can lead people to do things they aren’t really qualified to do.
A quick search on the Internet lends credit to the phrase first being used by Alexander Pope in 1709 in “An Essay on Criticism.” He wrote, “A little learning is a dangerous thing; drink deep, or taste not the Pierian spring: there shallow draughts intoxicate the brain, and drinking largely sobers us again.” The Pierian spring is a reference to the place where the Muses were born in the Pieria region of northern Greece. A corollary on the subject comes from T.H. Huxley in 1881, who questioned, “If a little knowledge is dangerous, where is the man who has so much as to be out of danger?”
Combining these two ideas yields a potential caution for the public or at least those who work around electricity. Just how do I prevent the danger when working on circuits that one with a little knowledge previously worked on?
The most obvious answer is only a licensed electrician should be working on electrical circuits and related equipment. In addition, no work should be performed on a circuit or system that is energized. Finally, no one should be within the arc flash range without the proper personal protective equipment and prior training.
The reality is all three guiding principles are violated daily. On average, there are 20 electrical contact injuries per day and one person electrocuted in the work place each day.
How does all of this relate to power quality? Power involves voltage and current, the primary ingredients contributing to these injuries and fatalities. They are related to each other by impedance, which can vary from tens of thousands of ohms of a dry-skinned human to near zero ohms of a metallic tool that accidentally falls across two different conductors at different potentials. The first scenario can lead to electrocution and death if the impedance is low enough to cause just milliamps of current to flow through the body and the resulting fibrillation of the heart. The second circumstance can generate a release of energy capable of incredible destruction from the heat and pressure wave.
Know the codes
Yet there are plenty of examples of improper wiring, grounding, bonding, critical loads not able to continue uninterruptible operation, and so on, which are the result of someone operating with a little knowledge of the fundamentals of power quality, the National Electrical Code in some cases, and even more often, the NFPA 70E, Standard for Electrical Safety in the Workplace, and various appropriate OSHA safety documents, such as OSHA 1910 Subpart?S and OSHA 1926 Subpart?K.
The facility maintenance person who is assigned to “just run another wire” for the new network printer may not possess all of the knowledge necessary to perform the task safely and properly and in a manner that will not cause ground loops, not have the heating element of the laser printer cause voltage sags that would affect other equipment on the same branch circuit, and not increase the harmonic currents that could cause over-stressed neutral conductors or transformers.
Perhaps the rest of the room has those orange colored outlets that someone called isolated grounds, but the person with little knowledge doing the installation has only three-conductor cable. So, to save time and money, he decides to just connect the equipment grounding and insulated screws (not isolated, since that is illegal according to the Code unless from a separately derived source) to the same equipment-grounding conductor. Or, even better, if they are supposed to be isolated, why bother to connect either of them. Then they are surely isolated, right?
One solution for these above scenarios is the National Joint Apprenticeship and Training Committee (NJATC), which not only trains electricians to be qualified on hundreds of typical jobs that they encounter every day, but also helps them on occupational safety and power quality (PQ). They also provide PQ-awareness training classes at various offices around the country.
The bottom line is that it’s best to leave it to the professionals. Unskilled workers who perform tasks for which they are unqualified can ultimately affect the productivity of a facility and perhaps even the life of the person(s) in the area. You can’t put a price on the value of safer work practices and professional electrical contracting installations.
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680.