I am looking for fuse and fuse terminal block suitible to be mounted in general enclosure installed in class I Div II ( certified ) location. The equiment to be used in the curcuit are intruments such as low power soleniod valve, pressure switch and pressure transmitter connected to a PLC I/O module certified for class I DIV II location. The circuit loop power is 24-30 VDC. My company is US-based oil & gas operator. I would be appreciated if anyone could help me on the following matters;
1. Which NEC 500 subcode which my application application relates to, NEC 501-3 or NEC-501-6?
2. If my application falls within NEC 501-3, does the fuse and fuse teminal block type need to be rated NEC 501-6.(b)(3) or just general type? According to ANSI/ISA 12.12 4.4, it states that " Fuses may be housed in general enclusures only when used for overcurrent protection of circuit which are not subject to overloading in normal use "
Fuse used in circuits which are subject to overloading in normal use must be the type suitible for use in DIV 2 locations or housed in an enclosure rated for DIV 1 location.
Note : This subsection precludes a fuse housed in general purpose from being used in motor circuit where a possibility of a stalled mortor opening the fuse exists, or where there is a possibility of an overload not caused by a fault in the circuit ".
In the first paragraph of ANSI/ISA 12.12.4.4 does not state that what type of fuse which may be install in the general encloure. But specified in the NOTE that a fuse must be rated NEC 501-6(b)(3) if the circuit is for mortor control.
My interpretation is the circuit above falls witin NEC 501-3 and general fuse can be house in a general enclusure. provided that there is a switch ( rated for class I Div, I ) for removing power form the equipment and fuse. But my colleague disagree with my interpretation. He interprets that the application above folls within NEC 501-6(b)(6).
3. What is the differnt criteria or intenton of NEC 501-3 and NEC 501-6?
1. Which NEC 500 subcode which my application application relates to, NEC 501-3 or NEC-501-6?
2. If my application falls within NEC 501-3, does the fuse and fuse teminal block type need to be rated NEC 501-6.(b)(3) or just general type? According to ANSI/ISA 12.12 4.4, it states that " Fuses may be housed in general enclusures only when used for overcurrent protection of circuit which are not subject to overloading in normal use "
Fuse used in circuits which are subject to overloading in normal use must be the type suitible for use in DIV 2 locations or housed in an enclosure rated for DIV 1 location.
Note : This subsection precludes a fuse housed in general purpose from being used in motor circuit where a possibility of a stalled mortor opening the fuse exists, or where there is a possibility of an overload not caused by a fault in the circuit ".
In the first paragraph of ANSI/ISA 12.12.4.4 does not state that what type of fuse which may be install in the general encloure. But specified in the NOTE that a fuse must be rated NEC 501-6(b)(3) if the circuit is for mortor control.
My interpretation is the circuit above falls witin NEC 501-3 and general fuse can be house in a general enclusure. provided that there is a switch ( rated for class I Div, I ) for removing power form the equipment and fuse. But my colleague disagree with my interpretation. He interprets that the application above folls within NEC 501-6(b)(6).
3. What is the differnt criteria or intenton of NEC 501-3 and NEC 501-6?
