Skip directly to site content Skip directly to search


Español  Other Languages


Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People
 Search
		×
			NIOSH
			NIOSH
				All CDC
				Submit
			For a full list of topics:A-Z Index
			Advanced Search
		Advanced Search


The National Institute for Occupational Safety and Health (NIOSH)


Section Navigation
			
			CDC Home








Controlling the Ergonomic Hazards of Wiring Tasks for Household Appliances						Print
																Related Pages
										1998
DHHS (NIOSH) Publication Number 98-108
Hazard
Employees who perform repetitive wiring tasks on assembly lines may be at risk of developing carpal tunnel syndrome and other musculoskeletal disorders of the hand, wrist, and arm. Because 88% of household appliances are electrically powered, many workers assembling household appliances perform wiring operations. Some workers attach up to five wires during a 20-second cycle time. Workers who make the connections by hand often wrap their fingers with tape at the location of contact stresses. The average amount of force required to connect a standard crimp terminal to its tab varies from 12 to 32 lb, depending on the gauge of the wire.
Controls
Engineering controls should be the primary means for reducing the ergonomic risks associated with wiring household appliances. The following controls should be considered:
**Low-Insertion-Force (LIF) Terminals.** Some appliance manufacturers have begun using low-insertion-force terminals to reduce the amount of force required to make electrical connections. LIF terminals have a lock-and-release mechanism to keep the terminal in place once it is connected. LIF terminals provide sensory feedback, since the worker can feel when the terminal is seated. Standard-crimp terminals require approximately 12 to 32 lb of force to attach to the tab, whereas LIF terminals require approximately 6 lb of force to attach — a reduction of at least half. These commercially available terminals reduce the contact forces to the forefinger and thumb, eliminating the need for workers to use hand tools to wrap their fingers with tape (See Figure 1).Figure 1. Two terminal options and Figure 2. Pneumatic hand tool
Figure 1. Two terminal options.  blank spaceFigure 2. Pneumatic hand tool.
**Pneumatic Hand Tools.** If LIF terminals are not practical, a pneumatic terminal insertion tool can be used for connecting terminals. The pneumatic tool can consist of a lightweight riveter having a special jackset for terminal installation. A riveter used at one company is capable of driving 1/8- to 3/8-inch rivets. The riveter is typically used with multiple strokes, although some wires are inserted with a single stroke. The tool is suspended from an articulating arm or a balancer to support the 2-lb tool and the air hose. The cost of this commercially available tool varies from $570 to $830, depending on whether it has a balancer or an articulating arm. The price does not include making the jackset, which must be made in-house by tool-and-die workers. Most appliance plants have a tool-and-die department, which can easily make the simple jackset for approximately $50. This pneumatic tool is well accepted by workers and is being used for many wiring tasks. The company mentioned above has purchased 50 of the pneumatic impact tools for wiring jobs and has reported a 32% reduction in faulty electrical wiring and a reduction in new carpal tunnel syndrome cases (See Figure 2).
**Ergonomically Designed, Manual Terminal-Insertion Tools.** If LIF terminals and pneumatic tools are not feasible, another method that alleviates some of the stresses of wiring is manual terminal-insertion tool. NIOSH researchers have designed a tool with which appliance assemblers can make electrical connections. This tool is not commercially available, but can be made by tool-and-die workers in house for approximately $50. Each end of the tool has a slot (one for large terminals, the other for small terminals) in which the terminals fit. The connector fits into the end of the tool so the assembler does not have to use a pinch grip to hold the connector. The size of the end may vary, depending on the wire gauge. The tool is designed to move the forces from the small surface area of the fingers to the larger surface area of the assembler’s hand. The handle is designed to conform to the worker’s hand. This tool may take more time to use until assemblers become accustomed to it, and not all connections can be made with the tool because of limited access. A similar tool can also be made for flag-type terminals (See Figure 3).Figure 3. ergo designed tool
Figure 3. Ergonomically designed manual terminal-insertion tool. Handle conforms to hand and ends are two sizes for different-sized terminals.
**Properly Designed Pliers.** If LIF terminals and specially designed tools are not feasible, pliers are preferred to fingers for terminal installation because they move the forces from the fingers to the larger surface area of the hand. If pliers are used as an interim measure, a handle length of at least 4 inches (preferably 5 inches) should be used to prevent the handle base from pressing into the worker’s palm; it should also have a spring return to maintain an open position. The pliers should be without finger grooves and should have handles that are almost straight (handle curvature should be no more than 1/2 inch). The high point of the handle curve should rest at the base of the palm, and handles should be identical for use in either hand. Such pliers are commercially available for approximately $30 (See Figure 4).Figure 4. Properly designed pliers
Figure 4. Properly designed pliers. Handle length is at least 4 inches and a spring return holds the handles open.Acknowledgments
The principal contributors to this publication are Cheryl F. Estill, James D. McGlothlin, Rosmarie T. Hagedorn, and Jerome P. Flesch.
This document is in the public domain and may be freely copied or reprinted. NIOSH encourages all readers of this HAZARD CONTROLS to make it available to all interested employers and workers.
Controlling the Ergonomic Hazards of Wiring Tasks for Household Appliances
							
					
							Last Reviewed:  June 6, 2014						Source: 	National Institute for Occupational Safety and Health
					Facebook
        Twitter
        LinkedIn
        Syndicate homeNIOSH Publications & Products
NIOSH-Issued Publications
Search NIOSHTIC-2 Research Database
Docket
Documents for Public Review
Peer Review Agenda
Databases
eNews
Federal Register Noticesplus icon
FRN Archive 2007-2010
FRN Archive 2005-2006
FRN Archive 2001-2004
FRN Archive 1996-2000
Press Releases and Updatesplus icon
Press Release Archives 2010-2013
Press Release Archives 2006-2009
Press Release Archives 2001-2005
Press Release Archives 1998-2000
Press Release Archives 1992-1997
Regulations
Regulatory Agenda
Science Blog
Software
Video Follow NIOSH Facebook
Pinterest
Twitter
YouTube
 NIOSH Homepage NIOSH A-Z
Workplace Safety & Health Topics
Publications and Products
Programs
Contact NIOSH


About CDC
					Contact Us
					800-232-4636
 Facebook Twitter Instagram LinkedIn Youtube Pinterest Snapchat
 CONTACT CDC
				Contact Us
							Call 800-232-4636
							Email Us
			ABOUT CDC
				About CDC
							Jobs
							Funding
			POLICIES
				Accessibility
							External Links
							Privacy
							Policies
							No Fear Act
							FOIA
							OIG
							Nondiscrimination
							Vulnerability Disclosure Policy
			CONNECT WITH US
				Facebook
								Twitter
								Instagram
								LinkedIn
							Youtube
								Pinterest
								Snapchat
								Email
			LANGUAGES
				Español
							繁體中文
							Tiếng Việt
							한국어
							Tagalog
							Русский
							العربية
							Kreyòl Ayisyen
							Français
							Polski
							Português
							Italiano
							Deutsch
							日本語
							فارسی
							English


U.S. Department of Health & Human Services
			Accessibility
			External Links
			Privacy
			Policies
			No Fear Act
			FOIA
			Nondiscrimination
			OIG
			Vulnerability Disclosure Policy
			USA.gov


Exit Notification / Disclaimer Policy Close
 Links with this icon  indicate that you are leaving the CDC website. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
				Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
				You will be subject to the destination website's privacy policy when you follow the link.
				CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Website Disclaimers
 Cancel Continue