Supply circuit for excepted circuits 5.3.5

[SCEEBT]

We are having some interpretation differences with this section of the NFPA79.



5.3.5.2supply circuits for excepted cirtuits shall be provided with all of the following:

(1) disconnect,transformer, etc... That ones clear.

(2) "Line side (of the supply circuit disconnect) supply circuit conductors, when internal to the control enclosure, that are seperate from and do not share a raceway with other conductors and are encased in rigid or flexible conduit if longer than 460mm (18in)."

One interpretaion of line (2) is that the supply for the excepted circuit MUST be tapped from the line side of the main disconnect (breaker). That the "Line side" is referencing the main disconnect. Another interpretation is that the taps could just as well be made from the load side of the main disconnect, and that the "Line side" is referencing the excepted circuit disconnect.

Section 5.3.5.1 states that the following circuits shall not be REQUIRED to be disconnected by the main disconnect. But it does not state that they CANNOT be disconnected

5.3.5.4 states "Where circuits are not disconnected by the supply circuit disconnect".... Again does not state that they cannot be.


Anyone have experiance with this in terms of compience with UL/ETL/TUV inspections.

 

[jim dungar]

5.3.5.2supply circuits for excepted cirtuits shall be provided with all of the following:

(1) disconnect,transformer, etc... That ones clear.

(2) "Line side (of the supply circuit disconnect) supply circuit conductors, when internal to the control enclosure, that are seperate from and do not share a raceway with other conductors and are encased in rigid or flexible conduit if longer than 460mm (18in)."

One interpretaion of line (2) is that the supply for the excepted circuit MUST be tapped from the line side of the main disconnect (breaker). That the "Line side" is referencing the main disconnect. Another interpretation is that the taps could just as well be made from the load side of the main disconnect, and that the "Line side" is referencing the excepted circuit disconnect.

Section 5.3.5.1 states that the following circuits shall not be REQUIRED to be disconnected by the main disconnect. But it does not state that they CANNOT be disconnected

5.3.5.4 states "Where circuits are not disconnected by the supply circuit disconnect".... Again does not state that they cannot be.

I read 5.3.5.2(1) as saying that the conductors feeding the required "separate disconnect" must be kept separate from other conductors IF they are internally connected to the supply side of the "main" enclosure disconnect.

5.3.5.1 and 5.3.5.4 are giving permission to have (2) sources of power to an enclosure.