Topic: panel breaker sizing for appliances & machines

User: megloff11x, Location: Kent, WA

Asked on: Tuesday, May 31, 2011 at 6:03 pm EDT
Answered on: Tuesday, May 14, 2024 at 6:03 am EDT

Question: I poked around the code book but didn't find a complete answer.How much large can the breaker at the panel be for a machine or an appliance? This is both a home and industrial question. I found a bit on the wiring but not so much on the breakers in the panel.I've had some replacements of machinery - same ampacity as the old. But when the day comes again, is there a rule or code citation to go by? I recently went to a larger AC unit. It was more efficient and only had a slightly greater amperage rating, but did not exceed the breaker used for the old unit. We had an electrician install it and handle those details. I would have liked to have gone larger but would have incurred a building re-wire & bigger panel.A non-work example, I once rented a house that had the clothes dryer hook up in the garage. The vent was there and it "shared" a 50A outlet with a welder - plug in which one you were using at the time. The dryer was your typical ~24A unit designed for the usual 30A plug, but the hardware store had the 50A plugs for clothes dryers too...When shopping for machinery I try to avoid buying something that will result in a $$$ re-wiring, or worse re-wire & new panel as we're usually already maxed out from previous "additions."I'm looking for guidance in this regard. What % of the breaker/outlet rating can the appliance or machine be before I'll burn my fingers if I have to flip the breaker. And how much smaller can it be before I have a fire hazard with the unit burning up while the protection takes no notice of this puny device?I would note the progression to home washers & dryers that can handle an Army GP Large tent on the one extreme and the higher efficiency other things that use a fraction of the power of their predecessors on the other.