Appliance Design - February 2008 - (Page 53) CORDS should not have any sharp angles. The radius of the arc formed should be at least eight to 10 times the maximum diameter of the cable and the cord should have a gentle bending motion that curves into a gentle arc when it is pulled to its sharpest angle. “The narrow end of the bend should look like a fishing rod with a large Walleye on the hook,” Oden says. By combining the correct strain relief, with the proper housing design, the cords set will be protected from damage during use. And, if the cord set is protected, then those that use the appliances will be protected as well. < For more information, enter: Conductive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .309 or email: sales@conductivecable .com Heyco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310 Or email: sales@heyco .com Interpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311 Or email: info@interpower .com Quail Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312 Or email: sales@quail .com Underwriters Laboratories . . . . . . . . . . . . . . . . . . . . . . .313 Or email: cec@us .ul .com Unicable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 Or email: larry@unicable .com This Interpower graphic shows a dome nut stress relief and how it enters the electronic housing. no lamp would ever see,” says Drengenberg. In this case, the cord goes through numerous twisting cycles to see if it causes a break in the internal wires.” Many UL appliance standards also require products to undergo a push back test. This test tries to force the cord back into the product’s housing. The cord is pushed into the housing in 1-in. increments, until the pressure exceeds 6 lbs., at which time the cord will likely buckle. This test is important because if the cord is pushed back into the housing while the device is in use, it could come in contact with hot components or with spinning motors. While UL and CSA are two of the primary places that OEMs should look to for standards, other bodies may have standards of which they need to be aware. Giglio says that if the cord is going to be used in a wet environment in Europe, it may require an IP enclosure rating from the IEC. Or, if it is going into a very hot application environment, the strain relief might need to be made of materials with flame retardant properties as mandated by NEMA. If selling products outside the U.S., OEMs need to double-check those country’s standards. While many are based on UL standards, or vice versa, many countries have their own rules including Canada, Japan, Mexico and the European Union countries. In some cases, the standards are being harmonized between the agencies so that compliance to one standard means that the strain relief complies with the second country’s standard. If there is any doubt about what standard needs to be adhered to, the suppliers encourage the OEMs to approach them as early as possible within the product’s design cycle to make sure that the requirements are met. Oden also suggests meeting with cordset suppliers earlier in the process design to ensure www.applianceDESIGN.com that the strain relief and the product design are designed to best protect the cord. For example, the designer has to design the size of the opening at the equipment end so that it can accommodate the cord and the strain relief. Or, when considering the strain relief external to the appliance housing, the designer must account for how the cord will bend. He says that a rule of thumb is that a strain or flex relief external to the appliance should be at 90-degrees to the exit axes and the housing QUALITY TO PROTECT PEOPLE LCDIs • GFCIs • ALCIs TOWER– LCDI GFCI ALCI • Customized to meet your specs • Priced from our own Asian plant to keep you competitive • Customer service from our USA headquarters for quick satisfaction 25 Reservoir Avenue, Providence, RI 02907 • Tel: 401-467-7550 • Fax: 401-461-2710 TOWERManufacturing Corporation www.towermfg.com For more Information Enter 123 applianceDESIGN February 2008 53 8/2/07 10:28:44 AM AD09074Tow2.indd 1 http://www.towermfg.com http://www.towermfg.com http://www.appliancedesign.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.