Question On 240 Wire Size And Ground For Wall Oven - Electrical - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum question on 240 wire size and ground for wall oven
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04-29-2011, 11:45 AM   #1
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question on 240 wire size and ground for wall oven

I'm getting ready to install a Wolf wall oven (single) and the mfg's install instructions tell me I need L1,L2 and ground 10AWG wire on a 30Amp circuit for their 240/208VAC 60 Hz oven. A few questions I have though:
1) Wolf states the 10 AWG is minimum requirement. The distance from the wall oven to the sub panel is approx 34'. Is that sufficient or should I go with 8 or 6? I live in Atlanta, Ga if that makes a difference. The county I live in follows NEC 2008.
2) Wolf also states that grounding through the neutral conductor is prohibited for new branch circuit installs. I'm not sure I understand this sentence. The house used to have a 6 AWG wire in place when we first bought the house back in 1993. That wiring had two black leads going to the breakers and a white lead going to the neutral buss bar in the sub panel. (Nothing going to the ground buss bar) So, wouldn't I wire the new 10/2 the same way? (I couldn't use that run because of the length is too short for where the new wall oven is going in the kitchen).

Thanks much for any clarification.

04-29-2011, 11:51 AM   #2
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well, since you live in GA. I think you should go with some 4/0 just to be sure.

Just kidding. A 30 amp breaker, per code, must have a circuit conductor no smaller than #10. The distance you have (34') is not enough to worry about voltage drop so, go with the 10 unless you are into overbuilding for some reason.

You new circuit will have 2 wires going to a breaker and the third (must be green or bare) going to the ground bar. If this is in your main panel, your neutral and ground bars should be bonded so they are both the same effectively.

 04-29-2011, 02:09 PM #3 Newbie   Join Date: Apr 2011 Location: Atlanta, GA Posts: 26 Rewards Points: 25 Nap, thanks for the feedback. If I can ask just two more follow up questions... 1) looking inside my sub panel which is located in the basement, I have four main wires coming in from outside... 2 black sheathed wires: one going to each bank of breakers, an aluminum looking wire (definitely not copper) going to the ground bar (buss) and a fourth wire with gray sheathing going to the neutral bar (buss). I don't see how the neutral and ground are connected, if I'm understanding your earlier comment. The old 6 awg that I pulled out (because it was too short in length) had a white sheathed wire going to the neutral bar. 2) I'm also out of open slots on my panel and was told by a master electrician to replace two 20 amp single pole breakers with a 20/30 quad so I can hook up my oven. does that make sense? The electrician actually was at my house this morning because I thought it made sense to add another sub panel, but he told me I could install this quad breaker to meet my needs and fore go the expense of a sub panel. I offered to pay him to do the sub panel or to install the breakers he recommended, but he said it was easy enough to do. Kind of strange that he drove all the way to my home and didn't want the work. didn't charge me for any of his time either! In case you need to know... I have 150 amp service, the sub panel in the basement is a Siemens G2040ML1200 (installed in 1993) Series B / Type 1 Enclosure if that helps.

 04-29-2011, 02:20 PM #4 Electrical Contractor     Join Date: Jun 2004 Location: Newnan GA Posts: 7,027 Rewards Points: 650 The old wire that was removed did not have a ground wire. In days of old, that was an acceptable practice. The instruction for your stove tells you the you could not use this wire even if it was long enough. When you run the new wire, the 2 hots would land on the breaker, and the bare wire will land on the ground bar. A subpanel has the neutral and ground seperate. I haven't looked to see if your panel will take quad, but that could be an option. Welcome to the site. __________________ "The problem isn't that Hillary Clinton lies. We all know she lies. The problem is that her supporters don't seem to care"
 04-29-2011, 04:12 PM #5 Newbie   Join Date: Apr 2011 Location: Atlanta, GA Posts: 26 Rewards Points: 25 JBFan, Thanks for the feedback and the clarification about the old way versus today's requirements. Between you and Nap's fdbk, I got it now. Just a side note, since I notice you're in Newnan. I'm in Kennesaw and we often go see a group called A1A... a Buffet tribute band based in Marietta. Not like Jimmy, but pretty close. Thanks again guys for your help.
04-29-2011, 04:56 PM   #6
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question on 240 wire size and ground for wall oven

double check that you do not need a neutral. Some ovens require a neutral for electronic times, clocks etc. If that is the case than the neutral and the ground have to be seperated at the oven. This wcould required the bonding strap removed at the oven.
This would require 10/3 wire. At the panel blck and red to brreaker, neutral to neutral bas and ground to ground bar.
If only 10/2 is required than at the panel black and white to breaker and ground to ground bar.

 04-29-2011, 10:53 PM #7 Newbie   Join Date: Apr 2011 Location: Atlanta, GA Posts: 26 Rewards Points: 25 NJMarine, thanks for the tip. The wall oven arrived today and I looked at the install instructions and also called the mfg just to double-check. The oven is strictly 240V. So I guess the timer, clock, is handled through the oven's electronics. (I really don't know enough about it) but the mfg told me the oven is 240V and not 120/240. So I think I'm set. Appreciate the heads up though!
 04-29-2011, 11:42 PM #8 " Euro " electrician     Join Date: Apr 2006 Location: WI & France { in France for now } Posts: 5,369 Rewards Points: 2,000 Normally I useally run 10/3 W/G NM cable for wall oven { unless if double oven then I will check the specs little more closer to verify the power requirment due some do take 40 amp circuit } The reason why I always run 10/3 due some case you may have some oven required netural there if not use just cap it off but Jamais ( Never ) cut it off some day you will need it if you change the oven for some reason. As far for your breaker box it can take tandem breaker without issue due you stated 20/40 space panel so it will work either way and Oui IIRC they do have quad verison as well just pay attetion where you land 240 volt circuit on quads { you will get 240 volts no question but the major quirk is watch the breaker postion when you hook up that all., GE breakers are diffrent story I will fill it in other time } Merci, Marc __________________ The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )
04-30-2011, 07:13 AM   #9
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Merci Beaucoup!

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