Table 450.3(A) OCPD for transformers

[smallfish]

I'm concerned about possible damage to a 4800/120-208 volt, wye, 3phase transformer and its secondary service-lateral conductors that provide the electrical service to a strip mall by the possibility of its secondary service-lateral conductors ground-faulting or short-circuiting.

Could it be that the utility's fuses on the pole are intended to protect the primary conductors to this transformer, the transformer itself, and its secondary service-lateral conductors to the strip mall on a fault?

Does Table 450.3(A) apply for the protection of this transformer?

If it does apply, which location limitation in the table would apply, "any or supervised" and if secondary overcurrent protection is necessary, where would the overcurrent protection be placed? Would it be placed where the secondary receives its supply at the transformer or at the service disconnecting means at the building?

Thanks

 

[iwire]

Could it be that the utility's fuses on the pole are intended to protect the primary conductors to this transformer, the transformer itself, and its secondary service-lateral conductors to the strip mall on a fault?

No, the fuses on the primary side are only there to ensure a faulted transformer does not take out the rest of an area.

Does Table 450.3(A) apply for the protection of this transformer?

Absolutely not if it is utility owned.

 

[Pierre C Belarge]

One way to look at this is to picture a Utility company, what do they do? Make money, or try to anyway.

Now, if the transformer/supply to a building was to take out a grid or at least a neighborhood, the Utility would loose many "cash registers", not just one. So think of it as the primary cut outs protect the "Cash Flow". :grin:

 

[iwire]

I'm concerned about possible damage to a 4800/120-208 volt, wye, 3phase transformer and its secondary service-lateral conductors that provide the electrical service to a strip mall by the possibility of its secondary service-lateral conductors ground-faulting or short-circuiting.

Here is what it can look like

That is 4" RMC with 600 CU inside.