Look at a service disconnect (for a pv install that was a line side tap) that was rated for 200 amps and the fuses are 150 amp so they ran 2/0 copper for the service conductors i asked the insp. if they should be 3/0 copper to match max disconnect ampacity and not pv backfeed capability and he said no it would be find i disagree any thoughts
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Service Disconnect
- Thread starter newt
- Start date
- Status
- Not open for further replies.
Your conductor should be sized to handle OCPD ratings. As 240.4 allows the conductor ampacity to be less at times when rounding off to next size OCPD. The enclosure or lug ratings and OCPD rating are two different variables. you are using 200A rated lugs & enclosure but only utilizing 150A. 2/0 @ 75C are rated 175A and should be acceptable. Check you voltage drops and other conditions of use.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
2/0 copper is probably an accceptable size for 200A service conductors in any case. However, even if it wasn't, the service conductors only needed to be rated for 150A (assuming that is the correct number for the PV output according to 690.8).
Article 230 simply requires service conductors to be protected by OCPDs that are rated no higher than the conductor. The fuses are the OCPDs, not the disco. There is no prohibition on using a disconnect that is rated higher than the fuses. After all, that's pretty much how a fused disconnect works; the disco can be rated higher than the fuses but not lower.
The code is a little lacking in that Article 220 doesn't specify how PV is supposed to be accounted for as a 'load', but the reasonable interpretation is 125% of the inverters' rated output as set down in 690.8
Article 230 simply requires service conductors to be protected by OCPDs that are rated no higher than the conductor. The fuses are the OCPDs, not the disco. There is no prohibition on using a disconnect that is rated higher than the fuses. After all, that's pretty much how a fused disconnect works; the disco can be rated higher than the fuses but not lower.
The code is a little lacking in that Article 220 doesn't specify how PV is supposed to be accounted for as a 'load', but the reasonable interpretation is 125% of the inverters' rated output as set down in 690.8
Last edited:
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Thanks I thought you had to size to it the disconnect in case a fuse was changed to the full rating of the disc.
Nope. If the fuse holder accepts a range of different values without adapters, it would be a good idea to mark the maximum fuse size inside the box. But other than that, it would be just like requiring that any branch wiring connected to a 200A main panel be rated for 200A in case somebody put in a larger breaker than the branch circuit was originally wired for. Not a code issue.
- Status
- Not open for further replies.