For NM cables going into a main panel or subpanel, is there a maximum # of cables that can be run through each 3/8", 3/4", and 1" cable connector? And is this controlled by code (I'm in California so it's CEC), by the manufacturer's rating, or by best practices?

  • Think you conduit instead of connector. Conduit is pipes/tubes, connectors are for connecting wires together, like wire nuts or wagos. There is a listed number of wires/cables(wire is better in conduit) in conduit. There are conduit fill charts online.
    – crip659
    Commented Feb 4, 2023 at 17:56
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    If you are talking about cable clamps at the panel, it's generally max of 2 cables per clamp. If larger than 12/2, probably one. Still, best practice, since you asked, would be 1 cable per clamp regardless of size. Commented Feb 4, 2023 at 19:40
  • @GeorgeAnderson I know when my electrician was replacing my panel he generally put in 2 per clamp. The problem isn't the cost of the clamps, it is how many separate holes you need to have in the side of your panel. Commented Feb 4, 2023 at 23:56
  • @crip659 I don't mean conduit, I do mean connector. The cable connector is what secures the cable coming into the panel. Commented Feb 5, 2023 at 15:18
  • They are usually called cable clamps. The ones that fit into the holes in the panel sides/walls. They protect the cable from the sharp hole edges and clamp the cable to prevent movement.
    – crip659
    Commented Feb 5, 2023 at 15:24

1 Answer 1


This is controlled by the listing of the cableclamp

The manufacturer of your cable clamps will publish a chart, in accordance with the listing of said cable clamps, that specifies how many of what size cables the clamp is tested to accept, so all you have to do is follow that chart.

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    Which, a is frequently the case, means that the code enforcement is "follow the manufacturer's directions" as the directions are part of the listing.
    – Ecnerwal
    Commented Feb 4, 2023 at 22:08
  • Thank you. Found it: halexco.com/pdf/… Commented Feb 5, 2023 at 15:30

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