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That's... not actually true at all. In fact, in large parts of the country it's /required by code/ to separate 240V and 120V circuits, such as in most of South

That's... not actually true at all. In fact, in large parts of the country it's /required by code/ to separate 240V and 120V circuits, such as in most of South Central Texas (pop ~5M or so). There are absolutely 120V panels, and they are commonplace. I will agree, however, that in much of the Midwest and Northeast it's more common to see single-panel installations. Separating the panels is important for safety, though, and it also allows better circuit routing when running the electrical.

tfvlrue 5y ago
This is really interesting. It must be region-specific, because I'm in the northeast and have never seen or heard of this practice. Residential power around here is delivered as 240V split phase. Meaning, the service entrance load center has a bus bar for each leg, and the neutral is 120V from either leg. So you can have 240V circuit breaker that spans both legs, or a 120V that uses one in combination with the neutral. How does the arrangement you're describing work? I tried searching for 120V-only load centers, but wasn't really finding anything. Or, did you mean bridge together the two legs on a traditional load center and use it as a subpanel of the service entrance?
- tristor 5y ago
  Yes, that's how it works. Residential panels technically aren't rated by voltage, they're rated by amperage and the number of breaker openings. What is generally done here in South Texas is that on the exterior next to the meter there is a small primary panel for all the 240V circuits, and off of that a 100A leg feeds a physically larger subpanel in the garage area that has both legs bridged, acting as a 100A subpanel for 120V circuits. Personally, I think having the 240V circuit panel outside is dumb, and the amount of times I've seen my or other folks breakers fail due to weathering is pretty much the reason why. How I've seen this done on new builds where care was taken is that both panels are brought indoors and the only thing outside is a split out to a subpanel specifically for the A/C / heat pump unit. Everything else comes indoors, there is a smaller panel setup for 240V and a subpanel for 120V circuits. Obviously as the power entering the home is 240V split phase, you must break out a subpanel for 120V only if that's your intention.

tfvlrue 5y ago

This is really interesting. It must be region-specific, because I'm in the northeast and have never seen or heard of this practice. Residential power around here is delivered as 240V split phase. Meaning, the service entrance load center has a bus bar for each leg, and the neutral is 120V from either leg. So you can have 240V circuit breaker that spans both legs, or a 120V that uses one in combination with the neutral. How does the arrangement you're describing work? I tried searching for 120V-only load centers, but wasn't really finding anything. Or, did you mean bridge together the two legs on a traditional load center and use it as a subpanel of the service entrance?

tristor 5y ago
Yes, that's how it works. Residential panels technically aren't rated by voltage, they're rated by amperage and the number of breaker openings. What is generally done here in South Texas is that on the exterior next to the meter there is a small primary panel for all the 240V circuits, and off of that a 100A leg feeds a physically larger subpanel in the garage area that has both legs bridged, acting as a 100A subpanel for 120V circuits. Personally, I think having the 240V circuit panel outside is dumb, and the amount of times I've seen my or other folks breakers fail due to weathering is pretty much the reason why. How I've seen this done on new builds where care was taken is that both panels are brought indoors and the only thing outside is a split out to a subpanel specifically for the A/C / heat pump unit. Everything else comes indoors, there is a smaller panel setup for 240V and a subpanel for 120V circuits. Obviously as the power entering the home is 240V split phase, you must break out a subpanel for 120V only if that's your intention.