4

Is there a safety concern or code requirement around mixing circuits from different phases (on different buses) in a single box? I want to pair 2 switches into a 2-gang box where the switches are on different circuits and the circuit breakers are on opposite buses.

T.J.L.
  • 126
  • 1
  • 6
Allan Burge
  • 41
  • 1
  • 1
    Might not be required, but this sounds like a good place to have the two breakers have handle ties. Someone in the future could turn off just one breaker thinking both switches/circuits are on it, but then finds out the hard way that the second switch is still hot. – crip659 Mar 11 '22 at 11:54
  • The breakers are on opposite phases so not in proximity to each other. – Allan Burge Mar 11 '22 at 13:14
  • 1
    Quite a few panels, the phases will switch back and forth. One single breaker will on one phase, the one right below it will be on the second phase. It is the way 240 dual breakers work. Might think about moving the breaker circuits around, so a handle tie can be used. – crip659 Mar 11 '22 at 13:50
  • 1
    "opposite phases, therefore not in proximity" see this on how panels are actually bused. – Harper - Reinstate Monica Mar 11 '22 at 18:23
  • Where in the world are you? you seem to be using US terminlogy but your comment that different phases are not in proximity does not jive with how north american panels are normally designed. – Peter Green Mar 11 '22 at 18:43
  • Canada! I have a Siemens 200A distribution panel, mounted horizontally. The existing breaker is on the top, tapped into the "top" bus, the new breaker is on the bottom of the panel and tapped into the "bottom" bus. I could switch positions on the new breaker but it would still mean that I have different circuits coming into the 2-gang box, (same phase). In a new build this scenario would probably not happen, but in a reno it's a real possibility. I checked with my local authority and there is no rule against this, only if you supply electricity from different panels, not circuits. – Allan Burge Mar 15 '22 at 23:47

1 Answers1

5

NEC 404.8(B) requires identified, securely installed barriers where voltages between snap switches exceed 300v, which is an issue with 277/480v systems, but not 120/240v or 120/208v.

NoSparksPlease
  • 17,999
  • 2
  • 15
  • 46
  • I am adding recesed lighting to a room and needed to run a new circuir so want to add a new switch at the side of the exixting one. – Allan Burge Mar 11 '22 at 13:19
  • 1
    If just a lighting circuit(usually don't use full ampage of a breaker), might be able to just add the switch and light circuit to the same breaker. – crip659 Mar 11 '22 at 13:56