6-3 Romex or #2 SER for 25' subpanel feeder?


Old 07-29-20, 07:45 PM
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6-3 Romex or #2 SER for 25' subpanel feeder?

I was planning on using 6-3 Romex for the 25' interior feeder run from my basement main panel to the attached garage, where my subpanel will go. But when I called local electrical supply houses to get info on availability of feeder wire and CH main lug panels, one gentleman with whom I spoke recommend I instead use #2 SER "because it's good for 90 amps vs 50 or 60." What do you think...which one should I use, and why?

Without going into a long backstory, the immediate goal is just two 120V, 15A branch circuits for table saw + dust collector (and two 240V to allow the option for 240V machinery, of which I do currently own one already), BUT do I want to allow for future possibilities such as electric heater and/or mini split with heat pump, electric car charger, welder, etc. My main is only 100A at the moment (will be upgraded next), so none of these are relevant at this time, but is it not a good idea to go above and beyond to allow for future possibilities?

I posted this previously, but here's an overview video of the install plan:

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Old 07-30-20, 06:40 AM
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Size the feeder based on future anticipated loads. Sounds like you should use the #2 SER at a minimum. You may want to consider using 1-1-1-3 AL SER for a full 100A. Also I suggest a 100A main breaker panel over a main lug panel.
Old 07-30-20, 09:56 AM
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I want to allow for future possibilities such as electric heater and/or mini split with heat pump, electric car charger, welder, etc.
If these are realistic future loads there is little question that the 6-3 NM-B cable (60 amp feeder) wouldn't be big enough if some of the power tools might be in operation at same time as welder or car charger.
Old 07-30-20, 10:08 AM
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For a shop-type setup, I'd say a 60A feed would be more than enough. Even if you have multiple 240v tools, you wouldn't be running more than one (or two if a dust collector) at the same time. I can't imagine you'd be using a large tablesaw and welder concurrently. Add a small heat pump or heater, no problem.

But then add an EV charger, and that is pulling ~30A by itself. Will you be using the welder, heater, and EV charger simultaneously? If so, 90A is the way to go. Or if the EV charger is more of a future project, 60A might save you a few dollars now.

End of the day, it's your decision and where you want to put your money.
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