Timeline for Sub panel feeder circuit wire sizing
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 5, 2021 at 23:34 | comment | added | ThreePhaseEel | @Eli -- that panel should suit quite nicely for your garage :) and using SER for the interior runs with the Polaris-type connectors will work (note that if you want to run the copper in the underground conduit at 90degC, you'll need 90degC connectors in the pull boxes -- most Polaris-type connectors are indeed rated to run that hot, but some aren't, so pay attention to the specs on what you buy if you do that) | |
| Jan 5, 2021 at 14:34 | comment | added | Eli | The 150A panel is a Cutler-Hammer (Eaton) BR3030B150. I'll likely stick with the 60A service as you described, but if I did want to go up to 70A, would it be permissible (and not inadvisable) to use 3 or 2 GA SER Aluminum cable to make the interior runs, assuming all relevant components were CU/AL rated and no-ox is used at the connections? I would use a split bolt (wraped with splice tape then plastic tape) or Polaris type splice at either end of the conduit. | |
| Jan 5, 2021 at 1:41 | comment | added | ThreePhaseEel | @Harper-ReinstateMonica -- not quite. 250.122(B) only applies when a conductor is upsized from the minimum required for a given ampacity, and Table 250.122 is based on the OCPD setting, not the wire ampacity | |
| Jan 4, 2021 at 12:36 | history | edited | ThreePhaseEel | CC BY-SA 4.0 |
fix 75degC ampacity
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| Jan 4, 2021 at 6:31 | comment | added | Harper - Reinstate Monica | Wait, for 75C #6 copper, I get 65A out of that table. That also has an impact on the ground wire. Since the wire is capable of >60A, the ground must be too, i.e. #8 | |
| Jan 4, 2021 at 2:08 | comment | added | ThreePhaseEel | @Eli -- btw, as a crosscheck, what make/model is said 150A panel? | |
| Jan 4, 2021 at 2:07 | vote | accept | Eli | ||
| Jan 3, 2021 at 23:56 | comment | added | ThreePhaseEel | @Eli -- exactly, the size of the main breaker in the garage subpanel doesn't matter provided it's not the "weakest link" in the circuit, a job that's reserved for the feeder breaker in the main panel | |
| Jan 3, 2021 at 23:50 | comment | added | Eli | Thank you, that was very informative! I already have a 150A main panel that was removed when I had the service upgraded to 200A, so ideally I can use that. One follow-up question on that, can I leave the 150 main breaker in that panel to use as a disconnect in the garage, provided that the feeder circuit is protected at the main service panel with an appropriately sized breaker? | |
| Jan 3, 2021 at 21:30 | history | answered | ThreePhaseEel | CC BY-SA 4.0 |