Are fused switches used as service disconnects required to be lockable?

[hmspe]

Possibly by UL 891? This is in reference to a transformer feeder per 2011 NEC 450.14.

 

[Martin B]

I think so. The fusing and the locking aspects are are actually separate issues. As far as a service disconnect, yes the electrician must be able to lock it out.

 

[iwire]

I think so. The fusing and the locking aspects are are actually separate issues. As far as a service disconnect, yes the electrician must be able to lock it out.

There is no NEC requirement to have a lockout means on a service disconnect.

Think of a typical main breaker panel.

 

[don_resqcapt19]

Possibly by UL 891? This is in reference to a transformer feeder per 2011 NEC 450.14.

I expect that you are using the word "service" as meaning working on the equipment and not as in the electrical service disconnect for the building.
The 2011 code requires that a remote disconnect for a transformer be lockable.

450.14 Disconnecting Means. Transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable, and the location shall be field marked on the transformer.

If the disconnect is at the transformer there is no requirement that it be of the lockable type, however, there are not many disconnects that are not lockable.

 

[hmspe]

Thanks for the replies. I generally edit my posts to keep them short and apparently this time I went too far with local terminology when editing.

By service I mean the switchboard which contains the utility meter and service disconnecting means. In this case it is a 3000A, 277/480V, NEMA 3R, EUSERC, non-walk-in lineup which includes a 3000A main fused switch and eight fused switches for distribution. I have a plan review comment asking for compliance with 450.14. I know that circuit breakers used in this type switchboard frequently don't have provisions for lock off, but I don't recall ever seeing a fused switch for this type low voltage switchboard that did not have lock off provisions. I know that the NEC does not require lock off provisions, but if there is some other document (such as UL 891) that requires the provisions it will change my response to the plan review comment.

I'd also be interested in hearing suggestions on how to deal with part 2 of 450.14, which requires field marking transformers with the location of a remote primary disconnect. I see field marking as an inspections issue, not a design issue. I get occasional review comments that say I need to include a particular field marking requirement in my drawings. That seems like playing "Whack-a-mole" because there's no way to guess what the hot button item of the day is. Listing all the possible NEC required field markings in every drawing is not exactly practical. I'm inclined to respond that field markings are the responsibility of the contractor, but that approach does not always play well with the reviewers.

 

[don_resqcapt19]

Thanks for the replies. I generally edit my posts to keep them short and apparently this time I went too far with local terminology when editing.

By service I mean the switchboard which contains the utility meter and service disconnecting means. In this case it is a 3000A, 277/480V, NEMA 3R, EUSERC, non-walk-in lineup which includes a 3000A main fused switch and eight fused switches for distribution. I have a plan review comment asking for compliance with 450.14. I know that circuit breakers used in this type switchboard frequently don't have provisions for lock off, but I don't recall ever seeing a fused switch for this type low voltage switchboard that did not have lock off provisions. I know that the NEC does not require lock off provisions, but if there is some other document (such as UL 891) that requires the provisions it will change my response to the plan review comment.

I'd also be interested in hearing suggestions on how to deal with part 2 of 450.14, which requires field marking transformers with the location of a remote primary disconnect. I see field marking as an inspections issue, not a design issue. I get occasional review comments that say I need to include a particular field marking requirement in my drawings. That seems like playing "Whack-a-mole" because there's no way to guess what the hot button item of the day is. Listing all the possible NEC required field markings in every drawing is not exactly practical. I'm inclined to respond that field markings are the responsibility of the contractor, but that approach does not always play well with the reviewers.

If the transformer is remote from the primary disconnect, the primary disconnect must be lockable. If you are the designer and the transformer is remote from the disconnect, you need to specify that the EC provide a means of locking the transformer disconnect switch.
If the plan reviewer is requiring such comments, it is likely because they have found that the ECs are not providing the code required markings, and it just makes the process easier at inspection time if the designer has specifically required the markings.

The code really doesn't care who provides the marking on the transformer. It only requires the marking be there. If I was doing the design or writing the project specs, I would put wording in that would require the EC to provide the marking.