Shock hazards, electrical

An additional benefit of intrinsically safe systems is the reduction of electrical shock hazards. It is cautioned, however, that intrinsically safe systems are not necessarily tested specifically for personnel shock hazards. 

Optocouplers are a class of devices with input current (/ ) and output current (70) coupled optically, but isolated electrically. They are used extensively in the automation industry and in laboratory equipments where large common-mode noise/voltage or hazardous electrical shocks are present in circuits between transducers detectors and controlling equipments. The simplest optocoupler is composed of an LED (input) and a photodiode (output) as shown in Figure 1.19. 

Beware of shock hazard if an electric kettle or hot plate is used. 

Because the output of these bridges is in the range of millivolts, the cables utilized to carry the signal are normally shielded with a braided or foil-lined sheath around individual wires. The shield, as a rule, is connected to the amplifier, but never touches the actual instrumented equipment (i.e., tablet press). If this rule is violated, a ground loop may generate electrical noise and present a dangerous electrical shock hazard. 

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage hazardous polymerization will not occur resistant to oxidation and thermal shock high electrical and thermal conductivity FP (NA) LFL/UFL (NA) AT (NA). 

Hence an earth leakage circuit breaker should be used in the MCC to protect the circuit against electric shock hazard. 

Worked Example for the Calculation of Earthing Current and Electric Shock Hazard Potential Difference in a Rod and Grid Earthing System... 

EARTHING CURRENT AND ELECTRIC SHOCK HAZARD POTENTIAL DIFFERENCE... 

EARTHING CURRENT AND ELECTRIC SHOCK HAZARD POTENTIAL DIFFERENCE Calculate the constants Kfi, Ka and for nse in eqnation 68 from IEEE80. 

Dalziel, C. F., 1972, Electric shock hazard, IEEE Spectr. 9 41-50 (Fehruary). 

SJ Duranceau, MJ Schiff, GEC Bell, Effects of Electrical Grounding on Pipe Integrity and Shock Hazard, order no. 90702, AWWA Research Foundation, June 1996. 

It is important for the clinical engineer to understand fully how standards are developed, how they are used, and most importantly, how they affect the entire spectrum of health-related matters. Standards exist that address systems (protection of the electrical power distribution system from faults), individuals (means to reduce potential electric shock hazards), and protection of the environment (disposal of deleterious waste substances). 

Class C extinguishers are intended for electrical fires, which, because of the potential shock hazard, preclude the use of water. Many class B extinguishers are also rated for use on electrical fires. Class D extinguishers are used primarily for reactive metal fires and a few other specialized applications. Due to the extra cost of these units, only those laboratories which actively use reactive metals need to be equipped with class D units. 

Electric shock hazard is particularly a concern in clinical biopotential monitoring where the patient may be in a vulnerable state of health. Bioelectrodes are desirably low-resistance connections to the body for amplifier performance reasons. As discussed earlier, they similarly can offer a low-resistance pathway to ground for electric fault currents. 

Electric DisposaL A disposer can be installed in any sink that has a full-size drain opening. For an assistive kitchen design, switch location, safety, and disposal location are the main design objectives. The on and off switch should be placed in an accessible area, possibly under the front lip of the countertop. Care should be taken not to position the switch where a wheelchair can accidentally bump the switch while the person is washing the dishes. It should also be located so that a person cannot contact the sink and switch at the same time. The electrical connection should be away from the water line and should be protected with a conduit pipe to eliminate any shock hazard. The disposal should be located away from any wheelchair-accessible area. 

Noncode wiring and switches present an explosion hazard (electrical spark) and a shock hazard (especially if there is water on the floor). 

Electrical hazards. These hazards have two main components shock hazard and electrocution hazard. The major electrical hazard to property/product stems from electrical faults (i.e., short circuits). 

Voltage and Shock Hazards. Inside the cell room, it is a practical necessity for operators to come into contact with live parts. Since some of the usual safety measures against electrical hazards do not apply, special codes of practice have been formulated. 

At construction sites, the most common electrical hazard is the grovmd fault electrical shock. The OSHA electrical rules reqrure employers to provide either (1) grormd fardt circuit interrupters (GFCIs) for receptacle outlets, or (2) an assraed equipment grormd-ing conductor program. Either method can eliminate grormd fault electric shock hazards. 

OSHA s inspection revealed that employees were exposed to electric shock hazards due to working near an overhead powerline, using damaged/repaired extension cords, and improper construction of electrical cords. 

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