Mike Dolt Enterprises
Mike Dolt Enterprises
User: Jacob S, Location: Connecticut
Asked on: Saturday, March 26, 2011 at 7:47 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:20 am EDT
Question: So after the whole powerbridge post, I have come up with a question. Although I did not read every post in that huge thread, I read enough to see that one of the main objections to the product was that flexible cord was being used as a replacement for a chapter 3 wiring method, since it was a ?permanent? installation.I also know that it was found that even though the product was listed as an assembly, since the cord is not compliant with the NEC, the product cannot be used compliantly. Basically saying that everything installed must meet all standards of the NEC, and the listing is not necessarily applicable.Now, I thought I have read for years on this forum that listed products can be built to standards that are different than the NEC, but since they are listed that way, they are compliant to install. Some examples that include flexible cord:*Gas direct vent water heaters that come with a cord and plug for connection. This is an appliance that will be installed permanently for 10 years?way longer than any home entertainment setup. It is permantly crimped/soldered into place. The units are listed and intended to be plugged in straight from the manufacturer. Since this is an NEC violation, what are you supposed to do? If the unit was listed to be plugged in, you can?t modify it and hardwire it. There is no provision in the NEC that I know that allows this installation, such as those found for dishwashers and garbage disposals.*Industrial machinery that was built and listed in a panel shop. I have seen tons of flexible cord used in this setting where a chapter 3 wiring method could have easily been used?even where flexibility, portability, serviceability was not necessary. But since it is listed, it is ok??I know I can come up with more, but I am confused as to when a listing can override the NEC and when the NEC can override a listing.Thanks!
The answer to your questions lies in the definition of a "listed product." A "listed product" is a product that has been evaluated and tested by a nationally recognized testing laboratory (NRTL) and found to meet the applicable safety standards. The NRTL then issues a "listing" or "certification" to the product manufacturer, which allows the manufacturer to sell the product as meeting the applicable safety standards.In the case of the powerbridge product that you mentioned, the product was listed as an assembly. This means that the NRTL evaluated and tested the product as a complete assembly, including the flexible cord. The NRTL found that the product met the applicable safety standards as an assembly. However, the NRTL did not evaluate or test the flexible cord separately.The NEC is a set of minimum safety standards for the installation of electrical wiring and equipment. The NEC does not allow for the use of flexible cord as a permanent wiring method. This is because flexible cord is not as safe as chapter 3 wiring methods, such as conduit or cable. Flexible cord can be easily damaged, and it can create a fire hazard if it is not properly installed.The NEC requires that all electrical installations comply with the minimum safety standards set forth in the Code. This means that the installation of the powerbridge product as a permanent wiring method would be a violation of the NEC, even though the product is listed as an assembly.In general, a listing or certification from an NRTL overrides the NEC. However, the NEC does have some provisions that allow for the use of products that are not listed or certified. For example, the NEC allows for the use of unlisted products in certain cases where the product is not available in a listed form. The NEC also allows for the use of listed products in a manner that is not specifically described in the Code, provided that the installation is safe and does not create a hazard.In the case of the powerbridge product, the use of flexible cord as a permanent wiring method is not allowed by the NEC, even though the product is listed as an assembly. This is because the NEC has a specific provision that prohibits the use of flexible cord as a permanent wiring method.The examples that you provided are different from the powerbridge product. In the case of the gas direct vent water heaters and the industrial machinery, the flexible cord is not being used as a permanent wiring method. The water heaters are plugged into a receptacle, and the industrial machinery is connected to a power source through a cord and plug. In these cases, the flexible cord is being used as a temporary wiring method, and it is not a violation of the NEC.I hope this helps to answer your questions. Flag for review