Dear Colleagues, NFPA 79 (1997) provides the following requirement regarding overcurrent protective devices...
"8.4 Overcurrent protective devices shall be located at the point where the conductor to be protected receives its supply." Then two exceptions are provided. However, it is not explicit if the exception is regarding the placement of the protective device at the supply point to the conductor, or is the exception regarding the provision of the protective device. In other words, does the exception allow the protective device to be absent under the given conditions? A similar section in EN 60204 (1997) is 7.2.8 "An overcurrent protective device shall be located at the point where the conductor to be protected is connected to its supply. Where that is not possible, no overcurrent protection is required for those conductors with current-carrying capacity less than that of the supply conductors, provided that the possibility of a short circuit is reduced by all of the following measures:..." This section clearly states that the exception allows not having any protection at all. It seems reasonable that the intent of NFPA 79 is the same as EN 60204 ... but I want to be a bit more certain. So...the basic question....IF all the conditions are met for either the first or second exception of section 8.4 in NFPA 79, may an overcurrent protective device be left out? And two follow-ups ...with regard to exception 1, the last condition "the conductor terminates in a single circuit breaker or set of fuses" means, for example, a 16 awg wire may get its supply from a terminal block fed by a 2 awg wire, but it must terminate at the other end in a circuit breaker or fuse sized correctly for the 16 awg wire. Is this correct? ...with regard to exception 2, the last condition "the conductor terminates in a splitter block, circuit breaker or set of fuses." This means that the 16 awg wire of the above example may also terminate to another terminal block. Is this correct? (i.e. splitter block = terminal block). Thanks in advance for any comments. P.S. does anyone know how to get interpretations out of NFPA? I have a question queued up at n...@nfpa.org that has been answered after a couple weeks of waiting. --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
