Electric Water Heater Wiring

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  #1  
Old 11-28-06, 10:33 PM
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Exclamation Electric Water Heater Wiring

I just purchased a new electric water heater. I am converting from gas to electric to avoid using a venting chimney. The house has a 220 50 amp breaker line that was for an electric stove that I no longer use. I want to use this line to power the tank. The local experts at home depot told me to get a double pole 30 amp breaker which seems right, however, the confusion for me comes in with the wire itself. I need to put in a junction box at the old stove and run about 10 more feet of wire to the tank. they told me to get 10-3 wire and that would be sufficient. The 220 line is much thicker wire and has 2 positive (black wires) and a bare grounding wire. I was going to connect black to black and red to black, and bare ground to bare ground, leaving the white unattached. Is this correct? Especially with going from thicker wire to 10-3.
 
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  #2  
Old 11-29-06, 12:24 AM
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First could you share the make and model of water heater?

Is this a tankless or storage tank electric water heater?

I'm somewhat concerned about the existing cable, is this an aluminum wire cable or copper wire?

It sounds like it may be an se u type cable. Is the bare a weave of several wires or single solid wire?

In most cases a 30 amp breaker is correct but you need to install according to the instructions that came with the heater.

In most cases a neutral is not required for an electric water heater. There are some high end models that do require neutrals so best to check what you have there.

You should also install a disconnect close to the water heater. Then run a flexible appliance whip to the wiring enclosure of the heater from the disconnect switch.

Please answer the above questions as it will help the forum understand what you have in your situation as it is not always clear in the beginng of a post.


Roger
 
  #3  
Old 11-29-06, 04:45 AM
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There are no experts at Home Depot or any of the big box stores. Sometimes you get a knowledgeable person, but they are by no means an expert. Take any advice there with a grain of salt.

Assuming this is a normal 240 volt water heater, you wasted your money on 10-3. All you needed was 10-2.

If the existing wiring for the stove is copper then you can safely use it. If it is aluminum then I recommend you replace it. Don't consider any method of joining copper to aluminum. It's not worth the fire risk. Personally I would replace all the way back to the panel regardless.

There are no positives in alternating current. The two black wires are hot wires. Each is at 120 volts. Together they make 240 volts. The other wire is a ground wire. For 240 volts you need two hot wires which make 240 and one ground wire. The ground wire is for safety and does not contribute to the 240 volts.
 
  #4  
Old 11-29-06, 08:50 AM
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220 volts

I think you will be fine with your connection. The white wire should not be used as the transformer supplies the neutral for each hot leg. I would suggest 10-2 THHN wire and do use the bare ground at all boxes.
 

Last edited by stripcard; 11-29-06 at 08:55 AM. Reason: wire size
  #5  
Old 11-29-06, 11:11 AM
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> 10-2 THHN wire

I think you are confused; there is no such thing as 10-2 THHN. Individual conductors used in conduit may have THHN insulation. The issue here is about a new 10-3 NM cable ("Romex") and an old range cable, probably aluminum SE type.

> If the existing wiring for the stove is copper then you can safely use it. If
> it is aluminum then I recommend you replace it.

I second Bob's recommendation here. Many older homes have aluminum range cables and an aluminum to copper splice would not be a good idea in this situation. AL-CU splicing is at best unreliable and at worst a fire hazard; especially on a continuous use, high-current load like the water heater.
 
  #6  
Old 11-29-06, 10:34 PM
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Originally Posted by Roger View Post
First could you share the make and model of water heater?

Is this a tankless or storage tank electric water heater?

I'm somewhat concerned about the existing cable, is this an aluminum wire cable or copper wire?

It sounds like it may be an se u type cable. Is the bare a weave of several wires or single solid wire?

In most cases a 30 amp breaker is correct but you need to install according to the instructions that came with the heater.

In most cases a neutral is not required for an electric water heater. There are some high end models that do require neutrals so best to check what you have there.

You should also install a disconnect close to the water heater. Then run a flexible appliance whip to the wiring enclosure of the heater from the disconnect switch.

Please answer the above questions as it will help the forum understand what you have in your situation as it is not always clear in the beginng of a post.


Roger

It is a GE 50 Gallon heater purchased at Home Depot. The house was built in 1983, so there is all newer wiring in the home. I am almost certain that it is the se u type cable. I used the gray, larger wire nuts for the connection. I have everything wired in, except for the cut off switch, which I can easilly add, and am just waiting to hear what the verdict is for safety from everyone on here before I pull the breaker. Thanks for everyone's help!
 
  #7  
Old 11-29-06, 10:36 PM
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I just googled it and it is definatly se u type cable that was existing.
 
  #8  
Old 11-29-06, 11:12 PM
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Question

So, I got from all this. 1- 50 gallon electric water heater...new wire spliced to an old #8.

Never asked or answered..Total wattage of said heater. where did # 10 come from?
Existing cable Copper or aluminium ?
SEU: Most likey AL. 1983 home, That was still in practice.

Don't we need to know the draw before we advise? Good,bad or indifferent.
 
  #9  
Old 11-30-06, 07:57 AM
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First off if that se u is aluminum you cannot use it. Connection of aluminum and copper in a wirenut will quickly suffer oxidation corrosion due to the dissimilar metals and become a fire hazard. You need all copper from panel to heater. The installation instructions on many hot water tanks will have a warning about using aluminum wire. Though this is generally directed at the connection at the hot water tank wiring terminals which are rated for copper only. Aluminum is not worth the risk IMO.

Remember do not apply electricity to the heater before you fill the tank with water or you will destroy the heating elements.

Ge makes one model of 50 gal heater at 240 volts that has two 5500 watt heating elements. All the rest that are 50 gal are 4500 watts. Your instruction manual for the installation requirements will specify a copper wire size. Either will most likely specify 10 awg copper at 30 amps. However look at your installation instructions and verify the electrical requirements.

If you can give us the Model # off the unit we can verify this for you.

The disconnect should break both hot wires so you will need a dpst disconnect rated 30 amps. I couldnt find an example at HD but i'm sure they have them. Here is one at lowes.........copy and paste

http://www.lowes.com/lowes/lkn?action=productDetail&productId=73267-334-3032V-SP-L&lpage=none

lectriclee:

Your right of course... I prefer to get model#'s of the appliance and then verify the electrical on the manufacturers website...gives me peace of mind....and I can see what they have.

Roger
 
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