Length of Current-limited conductors in building

[wbalsam1]

Hi: I observed an installation at a correctional facility that makes me wonder a little. The service entrance conductors (in question) to the facility building originate at an outside 300 kva dry-type pad mount transformer and travel 15 feet underground in ridgid conduits (2), then enter the building with an approximately 65 feet (total length) run to an MLO panelboard. The conductors have current-limiters connected within the MLO PB. The conduits are RMC but not encased in concrete or otherwise protected. They hang from the bar joists with unistrut. These conductors travel a long way into the building without secondary protection. Is this a code-compliant installation? Do I need to provide more info? If these are service conductors, they're a long ways into the building without ocp. If it's some kind of tap, seems like way too long a tap....Thanks

 

[Pierre C Belarge]

Seeing as we are both from NYS, I will answer how I see this. As per 230.70(A)(1), this would clearly be a violation of the location of the service disconnecting means.

 

[Joe Villani]

Unfortunately,

Not according to NYS interpertation of the "immediately entering the building"

I agree with Pierre, but I don't know if it would stand up in a court of law.



Joe Villani

 

[wbalsam1]

rephrase / clarify question

rephrase / clarify question

Let me phrase the question this way: When is it permissible to use current-limiting fuses at the load end of conductors.....in other words, at up to how many feet of conductor run within the building are these things permissible? It just seems odd to me that there's 50 feet of unfused service conductors, and then these current-limiting devices come into play right at the point where the conductors enter the lugs on the main lug panelboard. I have not seen them used this way...until now....

 

[iwire]

In my limited experience with current limiters they have been required by the utility to protect their equipment and not the service conductors.

'Nearest the point of entrance' has been a requirement for a good long time.

I wonder how this was approved?

 

[wbalsam1]

The job never went through the proper channels. There were never any engineered drawings for the padmount & service. And, it was done without benefit of any state agency permit. And without benefit of any inspection. I noticed it while in the electrical room on another code-related matter. Thanks for the info Bob, I'll call the PoCo super and see what he knows.