# Ocp on service



## zen (Jun 15, 2009)

When the poco feeds a service where is the ocp? The transformer? I usually see the poco feed in 250 500 and paralled 500. It makes sense their wire will be ok but ive seen service with the wire size like #2 on a 200 amp service probably from the previous service. . What protects the feeder from our first disconnect back to the poco

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## Dennis Alwon (May 9, 2009)

I have always seen fuses on the poles but I am not sure they only do one home. IOW, if 4 homes are on the transformer then they all go down-- not certain about that.

Squirrels drive the power company nuts because they short out the fuses


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## don_resqcapt19 (Jul 18, 2010)

Nothing protects the utility transformer or the secondary conductors. The utility primary fuse is to protect the utility distribution system, not the transformer or the secondary conductors. The don't want a transformer fault or a secondary conductor fault to take out more than that single transformer.

At a fire call I watched 500 kcmil conductors and 4" rigid vaporize as the 750 kVA transformer just continued to feed the service conductors current. About 30 minutes in the utility arrived on scene. The transformer was in an underground vault. He opened the vault and the secondary conductors were smoking so he left and went to a substation to kill the primary feeder. When he came back, he cut the conductors to the faulted service and then re-energized the transformer to restore the power to the other custormers.


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## wildleg (Apr 12, 2009)

I don't have the 2012 NESC, but this is from 97:



> Section 16.
> Conductors
> 164B
> 160. Application
> ...


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## zen (Jun 15, 2009)

Ty sir

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## LGLS (Nov 10, 2007)

A heavily loaded pole pig IFO a friend's house trips out during heat waves at least 2x every summer. The utility resets it and drives away.


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