Hooking up a new oven

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  #1  
Old 09-25-07, 01:47 AM
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Hooking up a new oven


I am remodeling my kitchen and am installing a new oven. The oven connections are as follows:
The new oven has Black, Red, White and ground (I assume this is a 3 wire 220v connection.)
In the old existing 220v box there are the following wires:
Black, Black, White, and Blue.
I am assuming Blue is a ground. It is 12 gauge.
The others are 10 gauge. Does it matter which black wire from the existing 220v box goes to the red wire on the new oven? I know white goes to white.
The old oven was a Maytag, with a 120v outlet on top of it for the old microwave. I have run a new dedicated 20amp circuit for the new microwave, which will be on top of the new oven.
Any help is appreciated.
 
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  #2  
Old 09-25-07, 02:40 AM
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Is the breaker 30a? Where does the blue connect at the panel? What are the specs (amps) for the new oven? Sure the "blue" isn't really green?
 
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Old 09-25-07, 05:16 AM
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How did you go from " The new oven has Black, Red, White and ground " to "I assume this is a 3 wire 220v connection?"

I count four wires in your description.

This is a four wire 120/240 volt oven.

Do not ever assume anything. By assuming the wrong thing you could end up dead.

Examine the other end of the wiring. See where those wires in the wall hook up. That will tell you which is the ground, which are the hots and which is the neutral.

Use your tester. That will tell you which wires are the hots and which are the neutral and ground. While it will not distinguish between the neutral and griound, it will at least point you to the correct two.

No, it does not matter which hot wire is which.
 
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Old 09-25-07, 05:17 AM
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How did you go from " The new oven has Black, Red, White and ground " to "I assume this is a 3 wire 220v connection?"

I count four wires in your description.

This is a four wire 120/240 volt oven.

Do not ever assume anything. By assuming the wrong thing you could end up dead.

Examine the other end of the wiring. See where those wires in the wall hook up. That will tell you which is the ground, which are the hots and which is the neutral.

Use your tester. That will tell you which wires are the hots and which are the neutral and ground. While it will not distinguish between the neutral and griound, it will at least point you to the correct two.

No, it does not matter which hot wire is which.

The blue wire should not be present. I suspect it was added somewhere along the way. If it is the ground (most likely) it should be green. Ideally you should swap it out for a bare copper wire or a green wire.
 
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Old 09-25-07, 09:40 AM
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Thank you for your reply. The blue wire inside the existing box goes to a 15 amp 120v breaker on the main panel, so it is not a ground.
Sorry for the confusion regarding "I assume this is a 3 wire 220v connection". You are correct. There are 4 wires connected to the oven. The installation diagram shows 2 scenarios, a 3 wire and 4 wire hook up. I just read it wrong.
In the 3 wire hookup the white and bare ground from the oven would be connected to the white in the existing 220v box. Then black to black, and black to red.
In the 4 wire hookup it would be black to black, black to red, white to white, and ground to ground. Could I disconnect the blue wire from the 120v breaker, attach it to the ground bar, and then attach it to bare ground wire from the oven?
I will pull new cable if needed, but it is about 100' from the main panel, through the attic, etc..
 
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Old 09-25-07, 09:49 AM
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If this is conduit, then use the blue wire to pull a green or bare wire.
 
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Old 09-25-07, 10:06 AM
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Combining 220v and 120v in the same conduit.

I am remodeling my kitchen and need a dedicated 20 amp circuit for a new microwave. The 220v existing box has a blue wire that goes to a 120v breaker on the main panel. The old oven had a 120v receptacle on top of it to plug in a microwave, which is where the blue wire was used. I am installing a new oven which does not have a 120v receptacle, so I do not need the blue wire.
Can I pull new wires or romex inside the existing 220v flex conduit for the 120v outlet? I would add a junction box in the attic for the 120v wires or romex, split off from the main 220v flex conduit with flex conduit to the 120v outlet.
Any help is appreciated.
Which would be easier, wires or romex?
 
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Old 09-25-07, 10:24 AM
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First, a few questions. Is the conduit continuous back to the main panel? What wires (number and gauge) are current in the conduit? What trade size and material is the conduit?

Which would be easier, wires or romex?
There are some cases where Romex is allowed in or should be installed in conduit, but this is not one of them. Individual THHN wires are much easier to pull into conduit than Romex (NM-B) cable. Assuming you can reuse the existing flexible conduit, you'll probably want to use stranded THHN instead of solid THHN as it is easier to pull.
 
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Old 09-25-07, 10:37 AM
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Single project, single thread. Multiple threads confuses people.

Run a separate line for the new 120 volt receptacle. It will be much easier.
 
  #10  
Old 09-25-07, 09:31 PM
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This comment is to Raycraft. I'm sorry I have asked questions that have caused you to respond with short and tense replies. I thought this was a website for a do it your self person to get help and answers to questions. I am not an electrician but I am not stupid either. Ben was more helpful and encouraging. You seem to be angry.

I consulted with both a licensed electrician and a building inspector today and was told that I can do what I propose, run 3 wires (black, white, and green) for a 120v dedicated line for the microwave, inside the conduit with the 220v wires (black, black, white and blue) with the blue wire being used as a ground for the oven, and it will be up to code.
Ben, thank you for your input. The 3/4" conduit goes from the panel to the oven.
 
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Old 09-25-07, 11:31 PM
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As always the inspector has the last word but blue by code can not be used as a ground nor can a wire that small be re-designated with green bands. Grounds can by code only be bare, green, or green with yellow stripe.

If you had grown up with Usenet you would realize that this is a very friendly place compared to Usenet groups. Raycraft may seem a bit short sometimes but his time is limited and he has a real job too as all do here so just bear with us. Remember honey is better then vinegar. <G>
 
  #12  
Old 09-26-07, 05:28 AM
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I did not say that you could not run the other wires in the same conduit.

You asked which would be easier, I gave you my answer. A new circuit using NM-B cable is easier than attempting to add wires to conduit.

If you do add wires to the conduit, do NOT add a new ground wire. Use the single larger size ground wire for both circuits.
 
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Old 09-26-07, 08:20 AM
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Make sure you correctly understood your inspector. It seems inconceivable to me that any inspector in North America would approve the use of a blue wire for grounding. Maybe the blue wire is actually a faded or color-shifted green wire?
 
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