Tapped or Parallel service

[iwire]

Give me an example of the 4/0 feeding 2 breakers. Would that be 2 breakers in one panel? If so I don't see where the article addresses this.

Here is an example of a typical use of the exception in my area, we have a five family apartment building with a public panel as well. All the main breakers are 100 amps but the riser is only sized for the calculated load. Looks like it might be a 200-250 amp riser.

 

[Dennis Alwon]

Thank you. I do understand that scenario and the seu cables are all , presumably, sized to the ocpd.

What at I don't see is why that riser is allowed to be smaller feeder 6 panels but the service wire in the ops case which feeds 2 panels is not okay

Do away with the meters in your case and what do you have. You have a small service conductor feeding 6 panels. That is why I am confused

 

[iwire]

What at I don't see is why that riser is allowed to be smaller feeder 6 panels but the service wire in the ops case which feeds 2 panels is not okay

In my opinion the OPs installation is fine up to the tap, once the 4/0 passes the tap point it only supplies one OCPD which eliminates exception 3.

Please admire my outstanding paint shop skills. (Thats sarcasm folks)

 

[Dennis Alwon]

Now I see where you were going with that. That makes sense. thanks

 

[Smart $]

In my opinion the OPs installation is fine up to the tap, once the 4/0 passes the tap point it only supplies one OCPD which eliminates exception 3.

...

I still say the 4/0 before the tap is not okay... but I guess we'll just have to agree to disagree yet again. :blink:

 

[iwire]

I still say the 4/0 before the tap is not okay... but I guess we'll just have to agree to disagree yet again. :blink:

Is there more than one breaker?

Than exception 3 applies. It is is just that simple to me.

But I can live with disagreement as our opinions mean nothing, only the AHJs will matter.

 

[Smart $]

Is there more than one breaker?

Than exception 3 applies. It is is just that simple to me.

But I can live with disagreement as our opinions mean nothing, only the AHJs will matter.

I'm not saying Exception No. 3 does not apply. In fact I agree with you that it does.. but on the same basis that you say the 4/0 after the tap is a violation (with which I agree), is the same basis for which I say the 4/0 before the tap is a violation. The Exception only excepts the sum of the breaker ratings relative to the service conductor(s) ampacity. It does not except the service conductor(s) ampacity to anything less than the rating of any one breaker rating it supplies.

I too am not going to lose any sleep if you don't agree...

 

[Dennis Alwon]

Smart what do you say about the photo that Bob posted in Post #41. Assume those meters are 100 amp and calculated load is under 200 amps, then would the riser with 3/0 copper be compliant?

 

[Smart $]

Smart what do you say about the photo that Bob posted in Post #41. Assume those meters are 100 amp and calculated load is under 200 amps, then would the riser with 3/0 copper be compliant?

Assuming the meters supply 100A disconnect ocpds, yes... 3/0 has an ampacity greater than 100A.