240.21(c)(4)

[jim dungar]

No, then you must have a circuit breaker rather than fuses.

The OP was about fuses.

(And (B)(1)(1)(b) and (C)(2)(1)(b) both allow termination at a "device" rather than OCPD.)

Huh?
(B)(1)(1)(b) and (C)(2)(1)(b) both say "overcurrent protective device at the termination".

 

[LarryFine]

I'd consider a fused switch to be a single OCPD that is an integral part of a disconnecting means, as permitted by 240.21(C)(4)(3). But the conductors are still required by (C)(4)(2) to terminate at the OCPD and not the disconnecting means.

I still don't see why you must differentiate the two components of a single device.

 

[david luchini]

The OP was about fuses.

Yes, but if you're not permitted to put the switch after the fuses per 240.40, and you're required to terminate at an OCPD per 240.21(C)(4), then you'd be required to use a c/b to comply with 240.21(C)(4). The fused switch would be not be able to comply with the requirements of both sections.

Huh?
(B)(1)(1)(b) and (C)(2)(1)(b) both say "overcurrent protective device at the termination".

(B)(1)(1)(b) :Not less than the rating of the DEVICE supplied by the tap conductors OR not less than the rating of the of the ocpd at the termination of the tap conductors.

(C)(2)(1)(b) :Not less than the rating of the DEVICE supplied by the secondary conductors OR not less than the rating of the of the ocpd at the termination of the secondary conductors.

 

[david luchini]

I still don't see why you must differentiate the two components of a single device.

Does the manual switch provide any overcurrent protection? No. So terminating at the switch would not meet the requirements of 240.21(C)(4).

240.21(C)(4)(3) allows the OCPD to be integral with a "disconnecting means" or to be located immediately adjacent thereto. But (C)(4)(2) doesn't allow terminating at the disconnecting means, it requires termination at an OCPD.

 

[steve66]

240.21(C)(4)(3) allows the OCPD to be integral with a "disconnecting means" ...

To me, that means they are one in the same. There is no difference between the switch and the fuses. They are both parts of one assembly. So there would be no difference between landing on the fuses and landing on the switch.


Steve

 

[LarryFine]

A single manual disconnecting means, however, even when in the same enclosure with fuses, is NOT capable of opening a circuit automatically on a predetermined overcurrent.

Per 240.21(C) and 240.21(C)(4), the transformer secondary conductors would "originate" at the transformer secondary and "terminate" at a single circuit breaker or single set of fuses.

Your first statement seems to contradict your second. A set of fuses cannot automatically do anything to more than one line at a time, whether there's a switch ahead of them or not.

 

[cpal]

Yes, but if you're not permitted to put the switch after the fuses per 240.40, and you're required to terminate at an OCPD per 240.21(C)(4), then you'd be required to use a c/b to comply with 240.21(C)(4). The fused switch would be not be able to comply with the requirements of both sections.

(4) Outside Secondary Conductors. Where the conductors are located outdoors of a building or structure, except at the point of load termination, and comply with all of the following conditions:
(1) The conductors are protected from physical damage in an approved manner.
(2) The conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors. This single overcurrent device shall be permitted to supply any number of additional overcurrent devices on its load side.
(3) The overcurrent device for the conductors is an integral part of a disconnecting means or shall be located immediately adjacent thereto.
(4) The disconnecting means for the conductors is installed at a readily accessible location complying with one of the following:
a. Outside of a building or structure
b. Inside, nearest the point of entrance of the conductors
c. Where installed in accordance with 230.6, nearest the point of entrance of the conductors

The problem with the applcation of the code is language vs intent.
(3) requires the ocpd to be "integral part of a disconnecting means "

I take that as a fused disconnect or a CB!!
(4) locates the disconnect.

as I read it terminating at a listed fused disconnect should satisfy this language and I can not imagine an inspector requiring other wise??

 

[LarryFine]

(2) The conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors. This single overcurrent device shall be permitted to supply any number of additional overcurrent devices on its load side.

The first sentence of #2 merely specifies one device or fuse-set as compared to the several mentioned in the second. It does not contradict #3:

(3) The overcurrent device for the conductors is an integral part of a disconnecting means ...

To me, #3 is clearly referring to the single device mentioned in #2, and is clearly including the fuses within a switched disconnect.

The fuses within a fused switch are clearly "an integral part of a disconnecting means." If the intent was that the fuses precede the switch, I believe it would be clearly stated.


Was that clear?

 

[cpal]

The fuses within a fused switch are clearly "an integral part of a disconnecting means." If the intent was that the fuses precede the switch, I believe it would be clearly stated.


Was that clear?

As far as I am concerned your preaching to the choir here!

 

[LarryFine]

As far as I am concerned your preaching to the choir here!

I know, and I was using your post to agree with you. My apologies for not give you credit.