I need to install a 30 amp breaker for an electric washer dryer that requires 230 volts in a 40 amp modern fuse panel box for a apartment. The box is fused with a 40 amp main breaker within an apartment house in the NY area serviced by Con Edison. One existing breaker is a dedicated 20 amp circuit for the 220 Air conditioner. I am hoping that I can mount a dial switch on the wall beside the panel (with a licensed electrician) that will allow only one unit to operate at a time with the correct amperage breaker for each unit to make sure safe conditions are maintained. I do not want to use any kind of knife switch or a generator transfer switch if at all possible. Thank you for your help.

  • Uh...have you called Con Edison and asked them what the actual service ampacity is? 40A seems awful small for a split phase service! Commented Dec 21, 2015 at 3:24
  • 1
    Yes, Service is only 40 amps. Small service =1960's construction. I have added 30 amp washer dryers to the 50 amp panels with no problems. They have an additional 15 amp home run for 2nd 110 ac. I just want to make sure I do not increase the load by having the 20 amp a/c and the washer/dryer, mainly the electric dryer on at the same time. If there were a fire you know a lawsuit would be coming my way. So I must be careful and want to be safe. Commented Dec 21, 2015 at 22:36

1 Answer 1


I am a bit confused by the question - I think you're saying there's a 40 amp panel with a 20 amp two pole breaker for an air conditioner you want to add a 30 amp breaker for a washer dryer unit, and you want to make sure the washer breaker and the air conditioner breaker don't go on at the same time. (Also, are you thinking break before make, and have it reversed in the question's title?)

Would it work to use a 30 amp DPDT switch on a 30 amp breaker, one throw going to the washer dryer, the other going to a disconnect with a 20 amp breaker feeding the existing air conditioner? For example this one

Hubbell 1388

looks at a glance like it would be adequate.

The AC and it's existing wiring probably has to be on a 20 amp breaker, so you couldn't just connect it to the switch. I think you could find a 20 amp disconnect to go between the AC throw of the switch and the existing wiring.

Is there another panel for the apartment? With all this on 40 amp main I'd see a lot of trips.

  • Thanks for your reply. Seems good to me. I will run your idea by my electrician and see what he thinks . You would think he would know what to do. Why do I have to always dream this crap up....... Commented Dec 21, 2015 at 21:37
  • Thanks for your reply, Seems good to me. I will run your idea by my electrician and see what he thinks. You would think he would know what to do......Why do I have to always dream up this crap.....I figured the switch would have three positions. One with nothing on and the other two for the ac and washer. Two positions one for each unit seems good to me. Sorry I am not familiar enough with electrical terms so I may state them wrong. Commented Dec 21, 2015 at 21:56
  • Sure thing hope it works for you. I think that switch is center off, i.e., neither's on in the middle position, as you figured. Commented Dec 21, 2015 at 22:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.