I have setup a new water heater where I used 10-2 wire to a disconnect box. Then, connected a square D 30 Amp dbl pole in my breaker box. Water heater connections were black to black white to red and grounded to plate. My breaker was Square D QO230 wired with Black to one pole and white to the other. I then grounded it. As soon as I turned it on the circuit tripped. I thought maybe I had my connections switched on the breaker so I switched them and the same thing happened. I am starting to think I am supposed to use two 30 amp single pole breakers but I thought that was the same thing as a 30amp double pole breaker does that sound right? Could it be I have a different issue?
Electrical – Breaker Breaker, Which should I use
circuit breakerelectrical-panelwater-heater
Related Solutions
It sounds like you may be mistaken as to how this is wired, or that perhaps I'm just not understanding your explanation. As others have mentioned, it's not possible to get 240 volts from a single pole in a 120/240V split phase system. Each tandem breaker provides 2 120 V circuits, this is true. However, if you measure between the terminals on a single tandem breaker, you'll get 0 volts. This is because the terminals are both powered from the same leg, and so are at the same voltage potential. If you measure from a terminal on the top tandem breaker to a terminal on the bottom one, then you'll measure 240 volts. This is because each breaker is connected to a different leg, which are each one half of a 240 volt circuit.
With all that said. For this setup to work, one appliance would have to be connected to both breaker. Something like this...
Notice that each appliance circuit has one wire connected to each of the tandem breakers. In this situation, you'd need a device like Speedy Petey shows.
Which ties the breaker handles together, to provide common trip characteristics.
Notice how the inner handles are tied together, and that the outer handles are also tied to each other. This way if either trip (or are turned off by the user), the entire circuit is shut off.
If this is wired the way you've explained, where the dryer is connected to the top tandem and the heater is connected to the bottom. Then there's some magic going on in those breakers.
Yes, it seems quite probable that there was an electric water heater at some point, and if the last two were gas, that circuit is probably unused. Leave it off, and check for anything not working; and/or follow the wires if visible, or look for a junction box near the water heater location that has a cable going in and no wire coming out.
Related Topic
- GFCI breaker has no power
- Why does the roof heater consistently trip the circuit breaker
- 5hp 230v single phase motor popping 30amp breaker
- Electrical – What to do about breaker that triggers main panel, and breaker that’s stuck
- Tandem Breaker is in half-off position. Unable to reset
- Wiring – How to intall GFCI breaker if wire for outlets is 12/3 using two breakers
- Electrical – New house generator AC breaker tripping
- AFCI breaker – ruined by fridge
Best Answer
You're in a QO panel; fortunately has unique busing so you can't misfit a breaker that doesn't belong, you can use either the OEM Square D QO230, or one of the UL-classified competitor models the CHQ230 or ITED230.
Since both wires will be hot, you must use tape or paint to re-mark the white wire a color. Typically this is done by wrapping it with black tape.
Ground first, not last
You should hook up the ground wire first. You said you hooked up the hots, then hooked up ground, then had a problem. You were lucky. You could have been shocked if you tested it without grounds present. The fact that you did grounds last makes it seem like the ground is at fault. It's not. It's simply the "canary in the coal mine" warning you of the problem. Hook it up first, and the problem will be more apparent.
Divide and conquer
Unhook all the wires, except for - anyone, anyone, Bueller? Ground wires. That's right, leave all ground wires attached.
Now, hook up one wire to the disconnect, open the disconnect, and see if the circuit can power up. If so, power down and attach the other wire to the disconnect, and test again. Now close the disconnect and test again. Now attach one onward wire to the water heater. Test again. Etc. etc.
At some point, adding a wire will cause the breaker to trip when turned on. Divide that further if possible. Now you're pretty close to the answer. If you're still stuck, ask.