SEC running through panelboard (cabinet)

[ohmbucket]

I know this has been adressed before and I've searched but I have a few questions pertaining to my situation. What I have is a 2" underground feed from the utility into a 200a all in one, the meter is on the left side then feeds to the 200a main breaker on the right with 2/0 or maybe 3/0 cable. I'm installing a 20kw genset with a ats rated as a service disconnect. I would like to set the ATS right next to the panel, then remove the cable from the 200a main breaker, splice it with polaris connectors, run it to the ATS, then back to the 200a breaker.
I would normally scrap the whole setup but now the utility requires minimum 2 1/2" conduit and I don't want to replace this conduit as it would cost a whole lot of pennies.

Question#1.) 312.8 How do I total the space including the panelboard?

Question#2.) Any problems with running the feed from the meter to the ATS then back in the same conduit, I can't think of one?

Question#3.) I don't understand what I need for grounding with this unit?

Question#4.) Anything else that I should be looking at while doing this, I cannot have the inspector tell me FAIL and not get power back the same day on this one, I'm alittle scared, ok a whole lot scared.

Thank you for any help that you can provide me. I'm very new to the trade and trying to learn it.

 

[david]

Application Example
If an enclosure has a wiring space of 4 in. wide by 3 in. deep, the cross-sectional area is 12 in.2 Thus, the total conductor fill (see Chapter 9, Table 5 for dimensions of conductors) at any cross section cannot exceed 4.8 in.2 (40 percent of 12 in.2), and the maximum space for conductors and splices or taps at any cross section cannot exceed 9 in.2 (75 percent of 12 in.2).


There are readily available resources such as the NEC Handbook that will give examples in the commentary section that can be helpful. The application example above is a sample from the NEC handbook

I?m curious thought if a 20 KW generator can handle the load associated with your 200 amp service that you would be transferring .

 

[Smart $]

...

Thank you for any help that you can provide me. ...

As David mentioned, a 20kW generator may not handle the load. The only way to know for sure is to do a service calculation per Article 220. If load is greater than gennie output, your design will have accomplish some load shedding.

 

[ceb58]

I know this has been adressed before and I've searched but I have a few questions pertaining to my situation. What I have is a 2" underground feed from the utility into a 200a all in one, the meter is on the left side then feeds to the 200a main breaker on the right with 2/0 or maybe 3/0 cable. I'm installing a 20kw genset with a ats rated as a service disconnect. I would like to set the ATS right next to the panel, then remove the cable from the 200a main breaker, splice it with polaris connectors, run it to the ATS, then back to the 200a breaker.
I would normally scrap the whole setup but now the utility requires minimum 2 1/2" conduit and I don't want to replace this conduit as it would cost a whole lot of pennies.

Question#1.) 312.8 How do I total the space including the panelboard?

Question#2.) Any problems with running the feed from the meter to the ATS then back in the same conduit, I can't think of one?

Question#3.) I don't understand what I need for grounding with this unit?

Question#4.) Anything else that I should be looking at while doing this, I cannot have the inspector tell me FAIL and not get power back the same day on this one, I'm alittle scared, ok a whole lot scared.

Thank you for any help that you can provide me. I'm very new to the trade and trying to learn it.

Well with your set up you could save money by not having a service rated ATS. The breaker in the combo is the service disco so there is no need for the SR ATS. As for the grounding from the breaker in the combo to the ATS and back to the main panel it will be 4 wire with the neutrals separated and isolated and the EGC bonded to the enclosure.