NEED to Convert 20 amp breaker to 30

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  #1  
Old 10-21-05, 01:24 PM
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NEED to Convert 20 amp breaker to 30

This is regarding a previous post in the water heater section. I have an electric water heater(4500 watt) that recently started tripping the circuit breaker. Upon the suggestion of John_Nelson, I checked the breaker and it was a 2 pole 20 amp with #12 wire but the unit needs a 2 pole 30 amp #10 wire. I figured that even if there's something wrong with the heater, I should at the very least start with replacing the breaker and wiring. My question is, how much does that type of job run, (I'm in the Chicago area and we're assuming conduit and not romex) and the heater is in the room adjacent to the room with the breaker but on opposite sides, so they're about 20-25 ft apart. I'm trying to decide whether to attempt this myself or call someone in. Any advice would be much appreciated. Thanks.
 
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Old 10-21-05, 01:35 PM
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Assuming you have 1/2" EMT conduit between the panel and the water heater, this should be a very easy job. You need to pull the black and red #12 conductors out of the conduit and replace them with black,red,green #10 THHN. You can even use the old wires to pull in the new ones. It's possible that the conduit itself can be used for ground in lieu of the green #10, but I would pull in the green #10 for ground. After the #10s are installed, change out the 20A DP breaker for a 30A DP breaker. In the main panel, the green conductor terminates where the other bare/green wires terminate and the black and red go to the terminals on the double pole breaker.

This is a huge advantage of having conduit installed; it makes replacing the wiring very easy.
 
  #3  
Old 10-21-05, 02:09 PM
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I'll take a closer look when i get home but at the actual circuit breaker, I only saw 2 black wires attached to the 20 amp breaker itself (no red). Do you think this is a problem? Also, the way it's set up, the heater has flexible conduit going into a small box on the wall (no outlets) then from there a pipe goes to another box on an adjacent wall (which has 4 outlets). This box with the outlets has 2 pipes coming out of it that go up vertically into the ceiling. I'm guessing that one of these pipes carries the wire for the heater. Why is it going through this box with outlets, and does this complicate matters? Since I'm not experienced with electrical work, I may be using the wrong terms so sorry if I'm confusing you.
 
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Old 10-21-05, 04:23 PM
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Two black wires is just as good as one black and one red.
 
  #5  
Old 10-21-05, 08:39 PM
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It's unusual to have an electric water heater in Chicago... I've never seen one. Yet.

I would run new conduit if possible. You'll probably have to replace the BX portion anyway as it's probably not large enough to accept 2 #10 and the ground.

I am curious to know why it only recently started tripping the breaker. Perhaps there are additional loads on the same breaker?
 
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Old 10-21-05, 11:14 PM
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ibpbooks

Thanks for the helpful tip. What do you think about what trinitro said about the bx probably needing to be replaced and not large enough to accomodate the 2 #10 and the ground?

John

Thanks for clarifying that. As you can see, your reply to my first thread has created a monster. I'm a lot more knowledgeable than when I first came to this board, but I still haven't fixed anything yet.

trinitro

I live in a townhome and as far as I know, they're all electric in our subdivision. It's great for the pocketbook. Another thing is though, we are sandwiched between 2 other townhomes and don't have too many windows so that cuts down on cost too. What exactly do you mean by BX? I'm not quite hip with the lingo yet. Also, I don't think there's anything else on that circuit. If you have a chance, read my thread on the water heater forum. There was a buzzing noise at the main panel when I tried to use the water heater. It goes away when the breaker is tripped (which is about 30 seconds after I reset the breaker) and I also tried to operate the heater at the lowest thermostat setting, which got rid of the buzzing but the breaker still would trip. Also, what do you normally charge for a job like this, either running new conduit or just replacing existing wire if possible? Trying to decide whether to do it myself or have someone do it.
 
  #7  
Old 10-22-05, 07:11 AM
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With a 20A breaker and a 4500W heater, the breaker is being used right up at its limit.
20A * 240V = 4800W

Depending upon water usage, this could be a continuous or long term load. Normally the thermostat will cause the power to cycle on and off, but if you run the water for a long period of time on a cold day, the water heater will simply stay on for quite a while.

Operating at near 100% capacity will cause breakers to overheat; breakers in residential use are only rated for _continuous_ service at 80% of their trip rating. Code requires that you install circuits that will only be used to 80% of their capacity for most loads.

My bet is that the breaker has simply aged and gotten more trip prone. It would be a violation to replace the breaker without properly matching the circuit to the load (30A breaker, 10ga wiring), but it seems reasonably that this circuit would work fine for quite a while before failing; it was right on the edge.

-Jon
 
  #8  
Old 10-22-05, 03:47 PM
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Originally Posted by Electric Blues
I'll take a closer look when i get home but at the actual circuit breaker, I only saw 2 black wires attached to the 20 amp breaker itself (no red). Do you think this is a problem?
Any color wire except green, white, or grey is acceptable for a hot. Black, red and blue are the most common colors for hots in 240V circuits.

Also, the way it's set up, the heater has flexible conduit going into a small box on the wall (no outlets) then from there a pipe goes to another box on an adjacent wall (which has 4 outlets). This box with the outlets has 2 pipes coming out of it that go up vertically into the ceiling. I'm guessing that one of these pipes carries the wire for the heater. Why is it going through this box with outlets, and does this complicate matters?
The flexible conduit is probably armored cable or BX and will likely need to be replaced also. It is a little more work, but certainly not a huge deal to replace the BX with a short piece of flexible conduit.

It is very common for more than one set of wires to run through a conduit, and that is what seems to happen in your situation. The wires for the receptacles travel in the same conduit as the heater circuit. If you do this job yourself, make sure to turn off the breakers for the other circuits in this conduit also. Open up any junction boxes along the conduit run to assist in pulling the new wires in.

Since I'm not experienced with electrical work, I may be using the wrong terms so sorry if I'm confusing you.
You're doing just fine so far.
 
  #9  
Old 10-23-05, 05:34 PM
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Success!!!

I just finished the rewiring a little while ago. I have to say that it took a little more elbow grease than I thought, but I got it done. The first wire wasn't too bad, but the hard part was that the heater was not grounded previously so I had to attach 2 #10 wires to the second wire and pull it through, which took every pound of the 180 I weigh to get it done. Basically, I had to replace 2 wires with 3. The wires are all hooked up, the heater is now safely grounded, and the breaker is now a 30 instead of a 20. Guess what? The heater is working, the buzzing at the main panel is gone, and not even 30 minutes have gone by and WE HAVE HOT WATER!!!! You can't imagine the sense of accomplishment I feel, especially since the only electric work I've ever done is changing an oulet or light switch. I couldn't have done it without this board. I would like to thank the following people for getting me through this:


John Nelson
ibpooks
Baldwin
winnie
trinitro
wtavcar

THIS BOARD ROCKS!!
 
  #10  
Old 10-24-05, 06:13 PM
MikeSch
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All the advice on this thread was quite good, but one thing was missed; conduit fill. I'm not sure on the codes in the US, but in Canada, conduit with more than 4 conductors must not be filled beyond 40% because of heat. You're comment on "my 180 pounds to get the wire through", makes be believe you may be over the fill of the conduit. Again, the advice was good, and US codes may be different than CDN.

Good job.
 
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