The panel in the house we just bought has the 30-amp dryer is connected by 4 wires (#10) to the panel where the black wire is on a 30-amp circuit breaker and the red wire is on another 30-amp circuit breaker. Is that correct? To me that totals 60 amps of current acceptable over the wire.

Thank you.

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    Are they on two halves of the same circuit breaker, with the handles connected by a bar, or two completely separate circuit breakers? Can you post photos of the situation? – ThreePhaseEel Mar 9 '19 at 15:10

Service panels have two poles of 120V each. Most loads you are familiar with, draw from one pole and return the same current to neutral, which is "in the middle". 240V loads draw 30A from one pole, and return 30A to the other pole.

Generally there are 3 possibilities here.

  • A 2-pole breaker, which is a double-wide breaker with a factory handle tie. This has both common trip and common maintenance shutoff. Both are mandatory for a single 120/240V appliance wired with a neutral, such as a dryer or range.

One thing about 2-pole breakers is that the "common trip" is actually an internal mechanism inside the breaker, it isn't the handle tie.

  • Two 1-pole breakers with a handle-tie, which is a UL-listed device that is field-installed. This has common maintenance shutoff only. This is acceptable for 240V-only (no neutral) appliances like water heaters and air conditioning units. It is also required for multi-wire branch circuits, but a 30A MWBC would be excessively rare unless you had two travel trailers.

  • Two individual breakers with no tie. These are only good at 30A for plain 120V circuits, such as ... um... gosh... small travel trailers that use a TT30 connection, and that's about all I can think of that uses single 30A. However, two 30A breakers can be handle-tied for use on plain-240V loads as mentioned above.

I have seen panels where a handle-tie was conspicuously missing, and then I look closer at the dust in the bottom of the panel, and there it is. It had fallen off while someone was moving breakers around. So check the bottom of your panel.

I accidentally bought a bunch of 30A 1-pole breakers. That's why I know so much about what they can and cannot do.

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2 x 30 amp 120 volt circuit breakers makes a 30 amp 240 volt circuit, as you need. However, as the comment by @threephaseeel implies, the breakers must be adjacent and the handles tied so that they will trip together to be code compliant. Also, they must use a list handle tie, not just a nail or such.

This assumes that the two breakers are in opposit legs, which is true if they are adjacent, in most panels. If they are in the same leg, they cannot produce 240 volts but will produce 0 if used together.

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  • 1
    For a dryer, you need a true common trip breaker not just a handle tie, as it's a combination 120/240V load – ThreePhaseEel Mar 9 '19 at 20:02

In a USA 240 V a/c circuit there are two breakers (usually in a single unit called a 2-pole common trip breaker) connected in series on a single wiring path so that the current alternately flows out of one breaker, through the wire connected to that breaker, through the load (here the dryer), out of the load and into the other wire and finally into the other breaker. So one does not add the current flowing in the two breakers; there is only one current path flowing through both breakers. The two breakers must be on different legs of the bus for this to work.

If your dryer circuit is supplied by two separate 1-pole breakers which do not have a common trip and if the two breakers are on separate legs of the bus (i.e., 240 V between the two breakers), then the dryer would work, but this would not be according to code and could lead to a dangerous condition or could possibly damage the dryer (not sure about the latter).

One could connect two breakers in an arrangement in which one would add the current in the two breakers. However this is not used because it is pointless, dangerous, and not according to code, but I will describe it so that you can better understand why you do not add the currents in the case you are asking about.

You could connect separate wires to two different breakers which are on the same leg of the bus (i.e., zero volts between them) and then connect those wires together with a third wire to go to a load. From the load another wire would go back to the panel but to the neutral, not to another breaker.

In this arrangement, the current passing through the third wire and supplied to the load (and carried by the neutral wire back to the panel) would be the sum of the currents through the two breakers. So if the current in each breaker was say 25 A, then 50 A would be supplied to the load. (Also the voltage of such a circuit would be 120 V, not 240 V as in the standard case.) But as I said you will not encounter this arrangement because it is not something that accomplishes anything that cannot be done safely and according to code.

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