KDough
Member
- Location
- San Jose, CA
- Occupation
- Electrician 42 yrs / Electrical Inspector 4yrs
I sent this to my colleagues to see what kind of answers I would get. Now I am putting it out to all of you. These are not trick questions and I am sure that each one has a correct answer but I’ll say right up front that I am not sure what the correct answers are in each case.
Ok, I am going to lay out a few scenarios. I want to know which are code compliant if any.
#1) you have a 100a service with 100a hot buss and a 100a breaker feeding a 125a lug only sub-panel. Then you put a 30a solar back feed breaker in the 125a sub panel.
#2) You have a 100a service with a 100a main breaker feeding a 100a buss that has another100a breaker feeding a 125a lug only sub-panel. Then you put a 30a solar back feed breaker in the 125a sub panel.
Are both installations code compliant?
Is one installation compliant and one not?
Are both not code compliant?
#3) you have a 200a service with 200a main breaker feeding a 200a buss. There is a 100a breaker on that 200a buss feeding a 125a lug only sub-panel. You put a 50a solar back feed breaker in the 125a sub-panel.
Is that code compliant?
#4) take the same 200a service in #3 above with the 100a breaker feeding a 125a lug only sub-panel but you change out the 200a main breaker to a 175a main. You put a 50a solar back feed breaker in the 125a sub-panel.
Is this installation code compliant?
In my opinion I really don’t know. At first I wanted to say that they are all code compliant and are keeping in line with the 120% rule. But if you think about what the 120% rule is trying to accomplish, and that is to protect the buss from over heating, then it may be that only one or none are code compliant.
I would like to get your comments and opinions on this.
Ok, I am going to lay out a few scenarios. I want to know which are code compliant if any.
#1) you have a 100a service with 100a hot buss and a 100a breaker feeding a 125a lug only sub-panel. Then you put a 30a solar back feed breaker in the 125a sub panel.
#2) You have a 100a service with a 100a main breaker feeding a 100a buss that has another100a breaker feeding a 125a lug only sub-panel. Then you put a 30a solar back feed breaker in the 125a sub panel.
Are both installations code compliant?
Is one installation compliant and one not?
Are both not code compliant?
#3) you have a 200a service with 200a main breaker feeding a 200a buss. There is a 100a breaker on that 200a buss feeding a 125a lug only sub-panel. You put a 50a solar back feed breaker in the 125a sub-panel.
Is that code compliant?
#4) take the same 200a service in #3 above with the 100a breaker feeding a 125a lug only sub-panel but you change out the 200a main breaker to a 175a main. You put a 50a solar back feed breaker in the 125a sub-panel.
Is this installation code compliant?
In my opinion I really don’t know. At first I wanted to say that they are all code compliant and are keeping in line with the 120% rule. But if you think about what the 120% rule is trying to accomplish, and that is to protect the buss from over heating, then it may be that only one or none are code compliant.
I would like to get your comments and opinions on this.