Question: UL Listed Cable with Conflicted Ratings
I have encountered some UL Listed cable with conflicting ratings marked on the cable and I am not sure how to interpret it. Can Listed cable have dual ratings such as Type TC, 600V, direct burial cable that is also marked NPLF 150V? If so, can I use it as fire alarm cable buried in earth? Also is the cable rated 600V or 150V or both? Please explain.
Answer
The cable in question is dual rated as both, Type TC, Power and Control Cable (QPOR), page 275 in the 2008 UL White Book rated 600V and for direct burial and Non Power Limited Fire Alarm Cable (HNHT), located on page 144 in the White Book, NPLF cable rated 150V and marked appropriately. Looking in the UL Wire and Cable Marking Guide located in the 2008 White Book in Appendix A, we note that in the table on page 9 Non Power Limited Fire Alarm cable (NPLF) is not suitable for direct burial applications, while Power and Control Cable, Type TC is suitable for direct burial if the cable is marked.
When a cable is dual rated, the cable must be installed in accordance with the NEC for that type of cable as well as in accordance with the Listing markings for that type of cable. You cannot mix applications that conflict with the installation application that it is being used for. For example, you cannot use the Type TC direct burial rating or 600 volt rating when using the cable as a NPLF cable. The direct burial marking and 600 volt rating is only applicable for the Type TC application. If being used as NPLF, the cable could not be directly buried in earth and could not be used in circuits that exceed 150 volts.
