Six OCPD Rule for SDS?

[busman]

Section 230.90 Exception 3 says:

Exception No. 3: Two to six circuit breakers or sets of fuses
shall be permitted as the overcurrent device to provide the overload
protection. The sum of the ratings of the circuit breakers
or fuses shall be permitted to exceed the ampacity of the service
conductors, provided the calculated load does not exceed the
ampacity of the service conductors.

This seems to not fall into any of the OCPD exceptions in 240.4. Am I missing something???

Second question: Is there a similar exception for SDS conductors?

Specific situation:

I have a failed 1200A circuit breaker that is on the load side of a 4160/480V transformer. The 1200A CB feeds a panelboard with 6 circuit breakers and the load is WAY less than 1200A. Is there a legal way I can bypass the 1200A CB (it is very old and replacement is not an option)?

As a side note, 240.3 mentions "Services" but it appears to apply to Equipment, not Conductors.

Thanks as always.

Mark

 

[augie47]

I think Note 2 to 450.3 will apply.

 

[busman]

I think Note 2 to 450.3 will apply.

That is EXACTLY what I was looking for. I did a "search" for the word "six", but didn't go as far as 450. Thanks SO much.

However, I still am confused by the "equipment" in 240.3 and "conductors" in 240.4. It seems that 240.4 does not include transformer secondary conductors, even though 450 does. Am I still missing something?

Mark

 

[augie47]

240.4(F) does not take care of that ??

 

[busman]

240.4(F) does not take care of that ??

I guess it might be implied, but I'm not seeing it explicitly. However, I'm OK with that interpretation. Thanks again.

Mark

 

[don_resqcapt19]

That is EXACTLY what I was looking for. I did a "search" for the word "six", but didn't go as far as 450. Thanks SO much.

However, I still am confused by the "equipment" in 240.3 and "conductors" in 240.4. It seems that 240.4 does not include transformer secondary conductors, even though 450 does. Am I still missing something?

Mark

Nothing in 450 applies to the conductors. Those rules are only for the protection of the primary and secondary windings of the transformer, not the conductors. The protection of the secondary conductors is per 240.21(C).

 

[busman]

Nothing in 450 applies to the conductors. Those rules are only for the protection of the primary and secondary windings of the transformer, not the conductors. The protection of the secondary conductors is per 240.21(C).

Don - thanks a ton.

Mark