Every hydronic boiler (for radiators) I've seen had a direct wire electrical connection into an adjacent box, meaning disconnection requires electrical work. I would like to my new boiler more portable and connect it using an appliance cord into an outlet.

Can I replace the direct wiring (NM or similar cable) and install an appliance cord with a plug on the other side, which can easily be unplugged, just like I did with various other appliance where that form of connection was optional (microwave, range hood, garbage disposal etc)?

  • If this is in conjunction with this question asking about sharing a circuit with other appliances then it's highly likely that not only is this a bad idea, but that it's not code compliant.
    – FreeMan
    Oct 12, 2021 at 17:29
  • What's the purpose of bringing the boiler's electrical connection out to cord-and-plug? Generator hookup? Oct 13, 2021 at 1:37
  • @ThreePhaseEel easy disconnect and reconnect
    – amphibient
    Oct 13, 2021 at 16:17

1 Answer 1


It's not on the permitted list, so it must meet all the conditions of

422.16 (A) Flexible cord shall be permitted (1) for the connection of appliances to facilitate interchange or to prevent the transmission of noise or vibration or (2) to facilitate the removal or disconnection of appliances that are fastened in place, where fastening means and mechanical connections are specifically designed to permit ready removal for maintenance or repair and the appliance is identified for flexible cord connection.

That is a very, very, very weak case, that will only fly with Code pedants who like you, and no inspector is going to accept that.

The best way to bring a furnace (and other appliances) out to a plug connection is to add a subpanel to your house's electrical system, and place the furnace's branch circuit in that subpanel. Then (or rather, from the outset) you install a generator interlock so the subpanel can be dual fed from utility and generator. On the generator backfeed, you bring that out to an inlet, which is simply a plug inset into the wall.

You can put as many circuits as you please in this subpanel, heck if an interlock kit is available for your main panel, you can put the whole kaboodle on the interlock.

Or it can be as small as a QO 4-space panel with a QO2DTI interlock between two breakers. One must be 2-pole due to the way that interlock fits.

  • OK I can live with a direct wired connection
    – amphibient
    Oct 13, 2021 at 16:18

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