3 wire retrofit for 4 wire oven

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  #1  
Old 07-24-16, 01:51 PM
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3 wire retrofit for 4 wire oven

Hi,

I'm in Redmond, WA doing my kitchen remodeling in the house which was build in 1983. After removing old oven/microwave I realized it was wired with 3-wires: 2 blacks (hot) and 1 bare (ground). I need to connect Ikea Nutid single oven to this setup. Manufacturer allows this 3-wires and recommends wire together neutral and ground.

Basically, questions I have:
  1. Is it safe to wire oven's neutral with the bare (ground) wire?
  2. Is it code compliant to do so?
  3. If not what are the options except to wire whole new cable from garage to the kitchen?
Thanks for your advice!
 
  #2  
Old 07-24-16, 01:56 PM
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Is it safe..... technically no and it is not code compliant.

What is the model of the single Ikea oven ?
Some appliances only require 240v.
 
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Old 07-24-16, 02:16 PM
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It is Self-cleaning convection oven. Voltage: 208-240V.

Confused on the manufacturer recommendations for 3-wire setup. Looks like they think this is safe. Manual attached.

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Last edited by ray2047; 07-24-16 at 02:36 PM. Reason: Rotate and enlarge image.
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Old 07-24-16, 02:39 PM
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Manufacturer allows this 3-wires and recommends wire together neutral and ground.... I realized it was wired with 3-wires: 2 blacks (hot) and 1 bare (ground)
It needs a neutral to work. You don't have a neutral. Usually bare ground can't be used as a neutral.
2 blacks (hot) and 1 bare (ground)
Is the ground stranded and wrapped around the conductors? Is this SE cable?
 
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Old 07-24-16, 03:06 PM
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Better to show the picture. One black, one black with red stripe, one bare ground on the back goes from the electrical panel in the garage. 4-wire (black, red, white, bare) comes from the new oven.

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Old 07-24-16, 03:20 PM
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Yes.... that is SE Al cable and is not up to current code.
 
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Old 07-24-16, 03:37 PM
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I don't know why they want a neutral when it says it is 240 volts, not 120/240.
 
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Old 07-24-16, 04:29 PM
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What options do I have? Only new 4-wire cable from the electrical panel or I can use existing old cable?
 
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Old 07-24-16, 04:31 PM
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The existing cable won't meet code so a new cable is your safe option.

Not recommended but you might test the oven with the neutral disconnected. If everything works then you could just leave the neutral disconnected and capped. Note because you have aluminum SE cable you can't use wire nuts*. You need special connectors such as AlumiConn connectors.

Guess: The neutral is required to provide 120 volts for the electronic controls and perhaps the warming option.

*Purple Wire Nuts are sold for copper to aluminum use but are not recommended because of their failure rate.
 
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Old 07-24-16, 05:07 PM
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The Ideal purple wire nuts are too small for that conductor size.
 
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Old 07-24-16, 05:42 PM
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I install wall ovens as part of kitchen remodels. Personally, I would not hook up this oven to your existing wiring. I would advise all new cable, 8-3 with ground.

The manufacturer (and grandfathered code) allows the ground and the neutral from the whip tied together only when the "neutral" wire from the house is insulated.

I also wonder why there is a neutral from the whip as was mentioned.

If I was desperate to use the existing cable, I would contact the manufacturer directly and ask if a 50amp 3-prong plug can be installed on the whip (there are plugs made for this), and the whip plugged into a 50amp range receptacle. I'm seeing more and more cooktops that are being plugged into 240V receptacles rather than hardwiring.
 
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Old 07-24-16, 06:01 PM
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But he can't use a 3-wire range receptacle because he has no neutral. That is the basic problem with any solution, no neutral. It would be interesting to see the wiring diagram for the oven.

The Ikea site refers you to the downloadable manual. Manual is one page that refers you to Ikea for help. Apparently it may be (?) manufactured by Wirlpool. Trying to find a wiring manual I found this: http://ths.gardenweb.com/discussions...atid-whirlpool If you just can't replace the cable you might look at other ovens. Some are 240 only and would work with your wiring.
 
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Old 07-24-16, 06:27 PM
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That is the basic problem with any solution, no neutral
I know there is no neutral. I was thinking the oven could be hooked up similar to a free standing range, which whether the range requires a neutral or not, it is allowed to use a bare wire in the cable depending on the cable type. Help me out
 
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Old 07-24-16, 06:35 PM
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As far as I know current rules are the same hard wired or plug. The pros though will have to give the final answer. I seem to remember that at one time 2-conductor SE could be used with the shield wire being neutral but I was thinking that is no longer true.
 
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Old 07-26-16, 06:41 PM
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No way would I try to resue that old aluminum SEU cable. My first observatrion made me wonder why it isn't in a box. AlumiConn connectors and purple wire nuts are too small for this wiring and purple wire nuts are known to fail and burn up. IF he used the old wiring, he'd have to use either aluminum split bolts or Polaris type connectors. The only real and safe solution is a new circuit.
 
 

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