Electrical – Is conduit required when running a short distance to an adjacent 60 amp subpanel

electricalelectrical-panelsubpanelwiring

I am installing a surface mounted 60 amp subpanel 5 inches to the right of my current surface mounted main panel. For the short run, can I use 6/3 non-metallic cable w/ground between the two panels using two clamp connectors and staple it to the plywood or do I have to run individual #6 THHN conductors and #10 THHN ground in conduit instead? I only have smaller size holes available on the side of my main panel, which makes attaching larger conduit to accommodate the 4 wires more difficult.

Best Answer

If you use cable, you are limited to the 60°C rating, so 6/3 isn't big enough for 60A - you'd have to go with 4/3

If you use conduit, and the terminations are rated for 75C, 6 (THHN) is fine. Also, if you use metal conduit, you don't need a grounding wire. The metal conduit is the grounding conductor.

Since it's less than 24 inches long, (a "nipple") you can fill to 60%, so 1/2" EMT, or IMC, or RMC will fit the 3x 6 AWG THHN wires you need (since you don't need a grounding wire, the conduit does that) - no large hole required. 75°C terminations are normal on service equipment, but do verify that yours are so marked - otherwise you are limited to 60°C ratings, in whch case you'll need the "larger of the small size holes" to take 3/4" conduit for 4AWG.