photovoltaic systems and the SES

[rbaker0206]

I'm trying to figure out what size of a system I can put on a 600 amp panel that has no main? it has 4 200 amp fused switches but no main. I understand the 120% rule from the rated busbar but what do I subtract to figure out the remaining availible space.

 

[Smart $]

I'm trying to figure out what size of a system I can put on a 600 amp panel that has no main? it has 4 200 amp fused switches but no main. I understand the 120% rule from the rated busbar but what do I subtract to figure out the remaining availible space.

Refresh my memory, what is the SES?

What supplies the panel, feeder or service conductors?

 

[Sierrasparky]

You don't subtract from available space. The rule is 120% of the rating of the buss, feeder, ...

So your max would be 600(if that is the rating of the buss) x.2= 120amps of backfeed.
If you are backfeeding from one of the subs then your max depends on where you place the backfeed and if the sub has a 200 amp main breaker of fuse.

 

[Smart $]

You don't subtract from available space. The rule is 120% of the rating of the buss, feeder, ...

So your max would be 600(if that is the rating of the buss) x.2= 120amps of backfeed.
If you are backfeeding from one of the subs then your max depends on where you place the backfeed and if the sub has a 200 amp main breaker of fuse.

The 120% rule doesn't apply to line side connections in service equipment... the reason I asked my earlier question.

 

[Sierrasparky]

The 120% rule doesn't apply to line side connections in service equipment... the reason I asked my earlier question.

I don't belive that opinion is entirely correct.

 

[rbaker0206]

SES is the service entrance.
which does not have a main.
I think I'm allowed to go up to the rating of the buss as long as there are less than six switches in the panel.

 

[Smart $]

I don't belive that opinion is entirely correct.

I'm referencing 2011 NEC. Look at 705.12 general statement. It says (A), (B), (C), or (D). Line side connections fall under (A) and the 120% rule is in (D)(2).

 

[rbaker0206]

I believe that a panel without a main falls under 690.64(A) supply side not(B) load side.

 

[Smart $]

SES is the service entrance.
which does not have a main.
No single main... it has four mains.

I think I'm allowed to go up to the rating of the buss as long as there are less than six switches in the panel.

You are allowed up to the rating of the service, which may be less than the bus rating.

 

[BillK-AZ]

If you have the exclusive use of one of the 200A fused switches, you can backfeed with an inverter that is listed for use with a 200A or smaller OCPD.

If you need to go higher, you need to consult with the SES manufacturer about installing a larger fused switch, likely the answer will be NO. Some of the smaller manufacturers (Sun Valley in Phoenix for some models) will offer UL listed kits for larger or additional fused switches, up to the rating of the utility service.

 

[Sierrasparky]

I'm referencing 2011 NEC. Look at 705.12 general statement. It says (A), (B), (C), or (D). Line side connections fall under (A) and the 120% rule is in (D)(2).

Is AZ on the 2011 code? Not many states are yet.

 

[Smart $]

Is AZ on the 2011 code? Not many states are yet.

According to Mike's Adoption List, AZ doesn't adopt the NEC on the state level and local ahj's are enforcing 2005. In the 2005 edition, this issue is covered, in part, under 690.64, as OP'er mentioned earlier. Additionally, the 120% rule is an Exception under 690.64(B)(2) for a dwelling unit installation only.

 

[cadpoint]

.... Additionally, the 120% rule is an Exception under 690.64(B)(2) for a dwelling unit installation only.

2008
OH, Really ? I just read it as a piece of equipment that happens to be properly sized for usage as determined... I don't understand the house remark...


A fused service is required because it's says so as a Solar install, the qualifier of a home verses other types of installs is not stated like that and doesn't change a requirement of a type of service to be installed correctly but as said where you put it might determine something else...

 

[Sierrasparky]

We all are assuming this to commercial but it could be at a residence.

 

[jaggedben]

I'm trying to figure out what size of a system I can put on a 600 amp panel that has no main? it has 4 200 amp fused switches but no main. I understand the 120% rule from the rated busbar but what do I subtract to figure out the remaining availible space.

I agree with Smart $. If you are adding it to a service entrance bus with no main, it is a supply side connection, and the 120% rule does not come into play.

2011 NEC

705.12 ...

A) Supply Side. An electric power production source shall
be permitted to be connected to the supply side of the service
disconnecting means as permitted in 230.82(6). The sum of
the ratings of all overcurrent devices connected to power production
sources shall not exceed the rating of the service.

The red part is new in 2011.
2008 690.64(A) reads the same without the red part.

 

[jaggedben]

So your max would be 600(if that is the rating of the buss) x.2= 120amps of backfeed.

The rule is that that the sum of the OCDs for power sources feeding the bus shall not be greater than 120% of the rating of the bus. Backfeed can be more than 20% of the bus rating if 'frontfeed' is less than 100%.

 

[Smart $]

2008
OH, Really ? I just read it as a piece of equipment that happens to be properly sized for usage as determined... I don't understand the house remark...


A fused service is required because it's says so as a Solar install, the qualifier of a home verses other types of installs is not stated like that and doesn't change a requirement of a type of service to be installed correctly but as said where you put it might determine something else...

I was referring to the 2005 NEC. It was changed in 2008.