Copious30
Member
- Location
- McConnells, South Carolina
- Occupation
- Electrican
Hello everyone! This is my first post but I have been viewing and learning from threads on here for a while. My father has been an Electrical Contractor/Master Electrician since 1996. I am currently studying for my master test(2020 NEC) for SC in May. The following is the way we have installed several feeders and meter combos, however I am now questioning it from the studying I have been doing. I have searched and searched here and I am having a hard time finding the info as I have seen many different answers.
Simply put, in a single family dwelling, can we use 4/0 aluminum SER from the feed through lugs of a 200 amp meter combo 8/16 space to a 200 amp sub panel more than 25’ away and install the outside HVAC in the meter combo panel and meet the 2020 NEC requirements? The interior sub panel would have a 200amp main and would have a load less than 180 amps. Our AHJ has never had an issue since 2017 with this exact setup.
310.12(A) (B) explains the 83% rule which would allow 4/0(200 amps) for service conductors supplying the entire dwelling. Since we are putting HVAC in the meter panel, we cannot use table 310.12.
In table 310.16 4/0 aluminum is rated at 180 amps at 75 degrees. Table 240.6(A) shows standard ampere ratings for breakers next size up would be 200 amps. I have also read about the rule that says a feeder downstream need not be larger than service conductors.
In this case I believe we are compliant with our setup?
Thank you for your time!
Casey
Simply put, in a single family dwelling, can we use 4/0 aluminum SER from the feed through lugs of a 200 amp meter combo 8/16 space to a 200 amp sub panel more than 25’ away and install the outside HVAC in the meter combo panel and meet the 2020 NEC requirements? The interior sub panel would have a 200amp main and would have a load less than 180 amps. Our AHJ has never had an issue since 2017 with this exact setup.
310.12(A) (B) explains the 83% rule which would allow 4/0(200 amps) for service conductors supplying the entire dwelling. Since we are putting HVAC in the meter panel, we cannot use table 310.12.
In table 310.16 4/0 aluminum is rated at 180 amps at 75 degrees. Table 240.6(A) shows standard ampere ratings for breakers next size up would be 200 amps. I have also read about the rule that says a feeder downstream need not be larger than service conductors.
In this case I believe we are compliant with our setup?
Thank you for your time!
Casey
. What you are looking for is 240.4 (B), so yes you can put 4/0 aluminum on a 200 amp breaker, even if the reduced residential wire sizes do not apply.