Larger OCPD

[redtruck]

Hello,

I am wondering if, where applicable you can install larger wiring and OCPDs than 125% of inverter or total PV system output.

I have multiple situations for why
#1 - Standard or available meter collars for a supply-side interconnection only come in 60 or 80a configurations. Say the output of my system is 55ampsx1.25=68.75 or 70a breaker. The meter collar's 80a is too large, no problem, I still run #4CU THHN, I do not want to buy a 100a fused disconnect to fuse down to the "appropriate" total system OCPD of 70A.
#2 I may install a system with plans to expand in the future, I can just install larger wiring and breaker right now thus making the total process of adding future strings or upgrading an inverter simpler in the future.

690.9(B) states OCPD are permitted to be rounded up to the next standard size. Is this inferring it cannot be sized up larger than one standard size?

I understand it is easy to simply install the correct wiring, I am just curious if you guys have done this. Normally when wiring up a load such as a motor, I do not want my OCPD to be needlessly large - I am trying to protect the wiring AND the motor itself. This however is power production, an inverter will not just overdraw current, will it?

Is my thinking flawed? Thanks

 

[solarken]

Hello,

I am wondering if, where applicable you can install larger wiring and OCPDs than 125% of inverter or total PV system output.

I have multiple situations for why
#1 - Standard or available meter collars for a supply-side interconnection only come in 60 or 80a configurations. Say the output of my system is 55ampsx1.25=68.75 or 70a breaker. The meter collar's 80a is too large, no problem, I still run #4CU THHN, I do not want to buy a 100a fused disconnect to fuse down to the "appropriate" total system OCPD of 70A.
#2 I may install a system with plans to expand in the future, I can just install larger wiring and breaker right now thus making the total process of adding future strings or upgrading an inverter simpler in the future.

690.9(B) states OCPD are permitted to be rounded up to the next standard size. Is this inferring it cannot be sized up larger than one standard size?

I understand it is easy to simply install the correct wiring, I am just curious if you guys have done this. Normally when wiring up a load such as a motor, I do not want my OCPD to be needlessly large - I am trying to protect the wiring AND the motor itself. This however is power production, an inverter will not just overdraw current, will it?

Is my thinking flawed? Thanks

You can install larger conductors and corresponding OCPD to accommodate future upgrade of inverter or for the other reasons as you describe. An inverter will only produce what it is rated for.

 

[jaggedben]

The only limitations here are:
- the breaker must protect the wire
- if there's a max OCPD specification for the inverter(s) you can't exceed that.

If there's no max OCPD spec on the inverter, no problem. Otherwise you could put an additonal OCPD in between the meter collar and the inverter.

 

[ggunn]

Hello,

I am wondering if, where applicable you can install larger wiring and OCPDs than 125% of inverter or total PV system output.

I have multiple situations for why
#1 - Standard or available meter collars for a supply-side interconnection only come in 60 or 80a configurations. Say the output of my system is 55ampsx1.25=68.75 or 70a breaker. The meter collar's 80a is too large, no problem, I still run #4CU THHN, I do not want to buy a 100a fused disconnect to fuse down to the "appropriate" total system OCPD of 70A.
#2 I may install a system with plans to expand in the future, I can just install larger wiring and breaker right now thus making the total process of adding future strings or upgrading an inverter simpler in the future.

690.9(B) states OCPD are permitted to be rounded up to the next standard size. Is this inferring it cannot be sized up larger than one standard size?

I understand it is easy to simply install the correct wiring, I am just curious if you guys have done this. Normally when wiring up a load such as a motor, I do not want my OCPD to be needlessly large - I am trying to protect the wiring AND the motor itself. This however is power production, an inverter will not just overdraw current, will it?

Is my thinking flawed? Thanks

The short answer is "any time you want". An inverter manufacturer may spec a maximum OCPD for an inverter but it is usually a lot bigger than 125% of the max current, so pay attention to that, but in case #2 you'll be giving each inverter its own OCPD, anyway.