New to the group here and hoping for solid guidance.

I have a 240v water heater that was removed as the house was converted to a gas exterior unit.

The 30amp supplies the 240v on a 10-2 wire.

What I’m working on is converting this 30amp 240v to a 30amp 120v sub panel.

My thoughts are to replace the main 30amp couple pole with a 30 amp single pole, so that I can wire the sub with this without replacing the 10-2 wire.

The end goal/use for this sub panel is to repurpose the 30amp so that I can add a 20amp breaker that will be dedicated for a crawl space dehumidifier and another 15amp breaker that will be dedicated for the gas tankless water heater now mounted outside.

Question for this group: Do I jump the hot to both hot lugs or can I just connect it to one lug if I only intend on putting both the breakers on one side.

If I don’t have to jump it, can I connect it directly to a single pole 30 amp breaker and connect it directly to the bar to act as a sub switch?

If none of these are advisable, any insight on the next best course of action? enter image description here

  • If your panel has adequate spaces (and it appears to) I'd just wire to the one hot lug and place your two breakers on spaces fed by that bus. That is rarely "one side" IME - most panels it's every other space, so double-pole breakers get 240V.
    – Ecnerwal
    Nov 7, 2021 at 15:10

1 Answer 1


Don't bother buying a single 30A breaker. Just leave the black wire on the breaker it's on, and move the white to the neutral bar.

Yes, you can split the black hot wire to the two poles of the subpanel. Do not put 2 wires on a lug, use a wire nut.

However if your reason for doing so is to buy a smaller and very slightly cheaper subpanel, I discourage this. Nobody ever said "wow, I got way too big a subpanel". But lots of people down the road say "wow, I wish I had gotten a much bigger subpanel!"

Who knows, if this subpanel is effective, you might want to upgrade it. After 10/2, the next larger size (by cost) is 2-2-2-4, which gives 90A.

  • It’s actually a 100amp remodel sub panel. Linked below. The issue is I’m just trying to repurpose the 10-2 wire rather than rewire it to a 10-3. The home of this wire right now is about 100ft away in a closet under the stairs and the journey to rewire is in between the 1st and second floor, over the carport into the garage where the main is located. My goal is to repurpose the 30amp and create 2 dedicated 15 amp and 20 amp circuits for the items mentioned above. Siemens E1020MB1100FCGP remodel Panel, Gray amazon.com/dp/B000M2XZNK/… Nov 7, 2021 at 5:27
  • When you say jump it, you’ll notice the panel box in the link above recommends feeding the hot into a double pole that feeds a hot to both bars. In this case, you recommend I pigtail the single hot into 2 at the sub 30 amp breaker, and at the main switch it to a single 30amp by adjusting the white from the breaker to the neutral bar? From there, I’ll just add the 15 and 20 amp breaker below that as per the norm? Nov 7, 2021 at 5:35
  • I do think there is such a thing as overkill. You aren't going to have capacity to add much load to that panel, you could save $50 and use a smaller two circuit disconnect homedepot.com/p/… Nov 7, 2021 at 15:40
  • @Ryen Nice panel, copper buses. A bit pricey, but that may be due to mail-order (electrical gear is overpriced mail-order because it's heavy, and shipping isn't really free lol.) This style of panel requires/provides a back-feed main breaker (since it has no lugs). Using the 100A breaker provided is fine. There is no benefit to changing it. Really. Attach to the lug(s) of the 100A breaker per instructions. Since you have plenty of spaces, feel free to just feed one lug. That will only energize every other space, but if you look closely at the bus-bars, you'll see which ones. Nov 7, 2021 at 19:06

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