I'm installing a glass kiln with specs of 240V, 30amp, 6-30R, with 60' run for wire. I need to run from the breaker box-in the garage-to the basement where the kiln will sit.

  1. What type of wire to use? What is the name for this? Does this size allow for run?
  2. Can I use conduit from the breaker to the basement-to look clean-and then leave the wire without conduit to the outlet box? Thanks for your help, V
  • If you can check the manufacturers installation instructions, sometimes they go beyond the minimum code requirements. NEC requires complying with UL, UL requires complying with instructions. Aug 9, 2020 at 16:19
  • Further, NEC requires complying with the instructions that UL approved as part of the UL listing. UL will never approve a thing that violates Code (although in certain corner cases, there are turf wars between NEC and UL, sort of like the territorial disputes between the US and Canada LOL). Aug 9, 2020 at 16:38

3 Answers 3


We don't generally worry about upsizing 240V wire until about 180', so 10 AWG will be fine.

You only need 2 hots + ground. If you use cable, consider using /3 (2 hots + neutral + ground). That's for 2 reasons: it's round; and it improves ability to reuse the wiring for other purposes later.

You can use any of the following wiring methods:

  • THWN/THHN wire in conduit - you might as well use stranded wire, which will be an easy pull
  • Cable in physically protected locations e.g. inside walls
  • Cable inside conduit provided the conduit is large enough

By "large enough" conduit, I mean the conduit's actual inside diameter must be 138% of the cable's widest width (hence the importance of round cable). However pulling any cable through conduit is quite hard, and upsizing just to make the pull easier helps a lot. A novice DIYer can easily wind up in a situation where you run out of swear words, and have to call in a professional :)

Anywhere you transition between THHN and cable, that must happen in a junction box. I recommend a 4x4 metal junction box so you have enough cubic inches. If you plan to ever use that conduit for other circuits, use THHN - multiple cables requires a HUGE conduit.

  • Awesome! Thank you so much for your time and expertise.
    – user121947
    Aug 9, 2020 at 18:07

30 amp 10 awg wire will be fine. using conduit From the box to your kiln is always a good idea and required in some locations. Use thhn wire. Thhn is almost always dual rated thwn and the conduit in the ground requires the wet rating. The conduit from your service to the receptacle box protects the wire your cord that plugs the kiln in can be used as the service disconnect. With 4 wire #10 1/2” conduit will work fine.

After answering I thought this sounds unusual is your garage attached and where your service comes in to the house?

  • 1
    Ed, The garage is attached to the house, it houses the main electrical box. The garage is finished with drywall-I wanted to use conduit from the main through the wall to the basement. Once in the basement I thought I could run a covered cable-romex-to the outlet-without the conduit covering it. I didn't want a covered cable running on the outside of the drywall to the main. Thanks for the thorough answer.
    – user121947
    Aug 9, 2020 at 18:03
  • Ok I thought that was the case but thought I should ask. My first house the service was on the far side of a 2-1/2 car attached garage but there was a breeze way so the distance was similar just wanted to make sure.
    – Ed Beal
    Aug 9, 2020 at 18:43

In addition to what Ed said, you can run conduit from the panel into the basement, install a junction box, and then run 10/2 with ground NM cable to your outlet box. The cable needs to be protected where it drops down to the outlet box. You'd use 2#10 AWG THHN wires in the conduit and the conduit would serve as your ground if EMT or RMC was used.

  • Thanks again for your information :)
    – user121947
    Aug 9, 2020 at 18:07

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