120% or 125% NEC backfeed rules as of 2014 code ?

[wanabefree]

If i understand correctly

1. Using a 125A bus in a panel that is delivered as an assembly with a 100A main is common practice among some manufacturers. It reduces the number of bus assemblies they need to make and stock. But the only way to tell for sure would be to get the manufacturer's specifications on the assembly or on the bus itself.

2. There are lots of options in the 2014 code on how to do backfeed. But it still comes down to the fact that if you are not able to feed into the opposite end from the main, you are limited to 100% of the bus rating, whatever that may be.
What is different is that, when calculating the backfeed number, instead of using the breaker size you can use 125% of the rated output of the inverter(s). Note that is the inverter output rating, not the size of the panel array feeding it.

It is possible that I very well could have a 125amp bus panel with a 100amp breaker. However proving it may be a problem because as I stated in my original post there are no marking anywhere on the manufacturer or the ratings. No stickers nothing even the original electrician who did the survey before installation said he did not know for sure.

Evan if that is true Since it is center fed I believe that at best they could use a 25 amp solar feed breaker and comply with the 120% rule. If I am reading your answer correctly in order to use the 125% rule the main breaker must be at the top of the bus and the solar back feed breaker at the bottom. then they may be able to justify a 30 amp feed breaker.

Personally I would prefer they just upgrade the panel to a 150 or 200 amp service and be done with it but it is not up to me unless the city refuse to approve what i have. I have been assured that no matter what is required They will cover all costs but only to bring it up to code not just because it is my preference.

[inetdog]

Ok here is my question or situation.
I just had a new 6.25kw system installed and all along the way have been going back and fort with the installer electrician as to what was legal regarding the NEC code. Well today I had a city inspector come to do a final inspection and he immediately said my panel would not pass because it had a center-fed 100 amp service breaker and a 30 amp solar back feed breaker at the bottom of the panel. The installer electrician said no this is a 125amp panel buss de-rated to 100amps and they do center fed panels all the time. That still would not allow a 30 amp solar breaker under the 120% rule . Now the actual main switch panel says the system feeds a max of 23 amps so in theory they might be OK with replacing the 30 amp breaker with a 25 amp but . There is no markings of any kind on my panel that says it is has a 125amp bus bar the electrician just says he knows it is because he has seem panels like mine before. The inspector say nuts to that and why would a 30+ yr old service panel be de-rated when the mains are clearly the original 100amp breakers. So then the electrician calls his supervisor and they have a discussion about the fact that supposedly in the new 2014 NEC codes they can now back feed up to 125% and if the panel is indead has a 125amp bus bar it would be legal.

So anyways as it stands now they have to go back and either prove the inspector wrong or now come out and replace my service panel as I have thought all along. The good news is they will fix it one way or another the bad news is i do not know how long this will take and it further delays my final and permission to operate.

Has anyone else come across this supposed new 2014 NEC backfeed rule ?

1. Using a 125A bus in a panel that is delivered as an assembly with a 100A main is common practice among some manufacturers. It reduces the number of bus assemblies they need to make and stock. But the only way to tell for sure would be to get the manufacturer's specifications on the assembly or on the bus itself.

2. There are lots of options in the 2014 code on how to do backfeed. But it still comes down to the fact that if you are not able to feed into the opposite end from the main, you are limited to 100% of the bus rating, whatever that may be.
What is different is that, when calculating the backfeed number, instead of using the breaker size you can use 125% of the rated output of the inverter(s). Note that is the inverter output rating, not the size of the panel array feeding it.

[wanabefree]

Ok here is my question or situation.
I just had a new 6.25kw system installed and all along the way have been going back and fort with the installer electrician as to what was legal regarding the NEC code. Well today I had a city inspector come to do a final inspection and he immediately said my panel would not pass because it had a center-fed 100 amp service breaker and a 30 amp solar back feed breaker at the bottom of the panel. The installer electrician said no this is a 125amp panel buss de-rated to 100amps and they do center fed panels all the time. That still would not allow a 30 amp solar breaker under the 120% rule . Now the actual main switch panel says the system feeds a max of 23 amps so in theory they might be OK with replacing the 30 amp breaker with a 25 amp but . There is no markings of any kind on my panel that says it is has a 125amp bus bar the electrician just says he knows it is because he has seem panels like mine before. The inspector say nuts to that and why would a 30+ yr old service panel be de-rated when the mains are clearly the original 100amp breakers. So then the electrician calls his supervisor and they have a discussion about the fact that supposedly in the new 2014 NEC codes they can now back feed up to 125% and if the panel is indead has a 125amp bus bar it would be legal.

So anyways as it stands now they have to go back and either prove the inspector wrong or now come out and replace my service panel as I have thought all along. The good news is they will fix it one way or another the bad news is i do not know how long this will take and it further delays my final and permission to operate.

Has anyone else come across this supposed new 2014 NEC backfeed rule ?