Transformer Secondary Conductor Protection outside of a building

[mattmcmahon]

I have a system that has a Main Distribution Panel feeding a 112.5 KVA 480y/277 Transformer located in the same room as the MDP. The Secondary 208y/120 conductors run about 125 feet Outside of the Building, then back into an Electrical room and feeds a Panel with a 400 Amp Main. There is no protection of the Secondary Conductors and the Contractor sites Article 240.21 (C)(4) "Outside Secondary Conductors" as negating the requirement for an OCPD located at the Transformer to protect the tapped/Secondary Conductors? I am unclear on 240.21 and would like to get others understanding of this Article.

Thanks,

Matt McMahon USACE

 

[augie47]

Close call. If the transformer were outside, then it looks like it would comply. In your case, it sounds like the conductors are inside at the point of supply.


(5) Outside Taps of Unlimited Length. 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

 

[dana1028]

Augie - do the rules of 230.6 apply?

I have often seen multistory buildings where the service comes in underground into a large vault, XO in the vault feeds through the vault to the outside...goes to another building and enters underground through concrete.

My understanding is these conductors would be considered 'outside' except at point of termination, and even then would be considered outside if the 2nd building panelboard was in another vault.

Am I correct in my understanding?

 

[augie47]

It's mixing articles, but IMHO it would apply. Also 240.4(F) might be applicable.