Range wiring

Discussion in 'Electrical and Wiring' started by Texas, Dec 11, 2009.

  1. Dec 11, 2009 #1

    Texas

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    I am looking at the supply to the stove/range (typical stovetop with broiler/oven below) in this old house and want to make sure they did it properly.

    I see a #10 ground, two #6 hots, and a #10 neutral, off a double pole 50A breaker. All wires copper, run <50'.
    Did they do it correctly?
    Thank you.
     
  2. Dec 12, 2009 #2

    Nestor_Kelebay

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    Can't say about the wire size, but I'll tell you all what I knows for sure...

    The 50 amp breakers is right. Electric ranges come in at least two standard sizes; 30 inch wide for normal residential stoves, and 24 inches wide for "apartment" size stoves. The bigger ranges will have two 8 inch surface elements (instead of only one) and larger bake and broil elements, and will typically require 50 amp service. That means 50 amp fuses on BOTH the black and red wires going to the range. Because there's no designated plug and receptacle configuration for 40 amp, 220 volt service, the smaller apartment size ranges will still use the same cord and plug as the large residential 50 amp ranges, but will typically be fused down to 40 amp service by using two 40 amp fuses or breakers instead of two 50 amp fuses or breakers.

    (Electric clothes dryers will typically have two 30 amp fuses and will use a different plug and receptacle configuration designated for 30 amp 220 volt service so that you can't plug a dryer cord into a stove receptacle or vice versa.)

    There's a convention in wiring terminal blocks, plugs and receptacles for 220 volt appliances, and that convention is that the three connection points will alway be in a straight line. The white neutral wire will ALWAYS be connected to the MIDDLE connection point, and the two hot wires (black and red) will be connected on either side of the white wire. It doesn't matter which side the black and red are on, so long as white is in the middle and black and red are on either side, you're good. That's true even if you have red connected to black on opposite sides of a terminal block, or if the stove's red wire connects to the prong of the plug that goes into the slot of the receptacle that the house's black wire is connected to. As long as white's in the middle and the black and red hot wires are on either side in both the plug and receptacle or on both sides of the terminal block, then it's kosher and your karma is in harmony with the universe.

    The fourth connection terminal for ground won't be in the same line (cuz that could cause confusion) and will always be easy to recognize cuz it'll be permanently electrically connected to ground and/or the steel electrical box the receptacle is mounted in.

    Dunno if this helps any. Hopefully an electrician in here can confirm that the wire sizes are OK.
     
    Last edited: Dec 12, 2009
  3. Dec 12, 2009 #3

    rdmayers

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    The wire size is correct for a 50 amp circuit,#6 is rated for 60 amps,but what i do not understand is you say the neutral is a #10. In a normal cable all the conductors are the same size except for the ground which would be #10.
     
  4. Dec 12, 2009 #4

    Nestor_Kelebay

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    Rdmayers:

    It's cuz the black and red wires both carry the same voltage, but they're out of phase by 180 degrees. As a result, the current and voltage of both the black and red wires (ideally) would cancel each other out perfectly where they meet at the white wire. So in a perfect world, the current and voltage in the white neutral wire should theoretically both be zero. How big a wire do you need to carry 0 amps at 0 volts?

    But, the real world isn't perfect and Lassie kills chickens. You'd get close to complete cancellation of the voltage and current in a stove ONLY because the heating elements in it act like almost perfect resistors. They have almost no reactance.

    It's when you put the black and red wires through reactive loads like capacitors (TV sets and CRT computer monitors) or inductive loads (like electric motors and electromagnets) that the current sine waves get out of phase with the applied voltage sine waves. And, when you have the current and voltage sine waves in both the black and red wires out of sync, when they meet at the white wire they won't cancel out completely, and you can have some residual current and voltage in the white wire.

    I'm certainly no expert on this stuff, and I don't want to give that impression. Hopefully, one of the electricians in here can explain reactive loads better than I did. But, rest assured, in a resistive load like a toaster, light bulb or kitchen stove, both the voltage and current from the black and red wires will almost completely cancel out where they meet at the white wire, so there won't be nearly as much current or voltage in the white wire as there is in the black or red wires, and so you don't need nearly as big a white wire to carry that small amount of voltage or current.

    I have a write-up on my computer hard drive that explains house wiring a bit better. I wrote it up for a lady that wanted to know how to install a cord and receptacle on her dryer so that she could clean under and behind it easier. If anybody wants, I can post it here. It explains about the phase difference between the red and black hot wires in 220 volt wiring and why the voltage and current in the white wire isn't always zero.
     
    Last edited: Dec 12, 2009
  5. Dec 12, 2009 #5

    rdmayers

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    I guess you did not understand what i was saying. Normally all the conductors in a cable are the same size. they do not under size the neutral. So the question i am asking is how there is only a #10 neutral. I understand exactly how everything works.and i also understand that they do not under size the conductors in a cable. I am not questioning if the conductor will carry the load, the only thing the neutral is used for in a electric range is the timer and light. I am just asking how the #10 neutral got there.
     
  6. Dec 12, 2009 #6

    travelover

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    I think the neutral is there for the 110 volt applications of the range (like the light, timer, etc). As Nestor so succinctly pointed out, the 220 volt current flow is all through the red and black wire. And the ground wire is just that - a ground wire.
     
  7. Dec 12, 2009 #7

    Nestor_Kelebay

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    Yes, you are right. Now that I come to think of it, every range and dryer cord I've ever installed had a white neutral wire of the same gauge as the red and black wires, even though it would appear that it didn't need to be as big.

    We need an electrician in here to tell us whether the reason the neutral is the same size just because of electrical code requirements. It's a guess, but I'm guessing the electrical code requires the neutral to be of the same size in the event of a short circuit. If the neutral were required to carry the same current as the black or red if the range shorted out, then undersizing the neutral could result in a fire.
     
  8. Dec 12, 2009 #8

    rdmayers

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    Nobody seems to understand what i am asking. I would like to find out how a #10 neutral got to the range location. I know what the neutral does once it get there. What I am saying is they do not make a romex with 2 #6 and a #10 neutral and a #10 ground. So I just wanted to know how the neutral ended up being a #10. Did they run conduit to the range location and pulled the conductors in it, or did they run a 6-2 with ground an ran a single conductor #10 for the neutral,which would be against code. So for the third time, how is the #10 neutral getting there. That's what i want to find out.
    Texas asked the question if it was done correctly.I can not answer this until i find out how the #10 neutral gets there.Is this so had to understand.Everyone want to reply,but nobody want to answer my question
     
  9. Dec 12, 2009 #9

    Nestor_Kelebay

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    RDMayers:
    That's cuz only Texas can answer that question.

    Texas: Can you describe the wiring between your electrical panel and your range please.
     
  10. Dec 12, 2009 #10

    Blue Jay

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    Can't tell you in this case, I know I have seen older wire with a smaller neutral but they did NOT have the ground wire.
     
  11. Dec 13, 2009 #11

    speedy petey

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    I don't think any of us can accurately answer this, not just you.
    Texas posted this one and only post two nights ago and has not been back since. EVERYTHING from here on out is purely speculation until (unless) he returns.


    Actually, unless there are other problems/circumstances we don't know about it is likely a compleltey complaint installation.

    210.19 Exc. 2 tells us this:

    Exception No. 2: The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall-mounted oven, or a counter-mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range of 83/4-kW or more rating has been calculated according to Column C of Table 220.55, but such conductor shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 AWG.
     
  12. Dec 13, 2009 #12

    Nestor_Kelebay

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    And here I got into a bar fight last night with a guy who insisted that "ampacity" was a real word. Now I'm going to have to visit him in the hospital and apologize.

    OK, so provided that the 10 gauge wire meets the requirement of being able to carry 70 percent of 60 amps, then we can assume the wiring was done by someone who knew the electrical code, and almost certainly did it correctly.

    But, RDMayers point still remains, and I'd like to know (and probably all of the other non-electricians in here, too)... how could that physically be done if you can't buy a cable with an undersized white wire? Would you run a #6 two conductor cable to the range and then what? Have the 10 gauge neutral wire strung across the kitchen ceiling between the electrical panel and the stove and doubling as an indoor clothes line?

    Or do they make special cables for ranges with an undersized neutral just because the code allows a smaller neutral in certain circumstances?
     
    Last edited: Dec 13, 2009
  13. Dec 13, 2009 #13

    speedy petey

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    Well, according to Firefox it is not a word, but I know it is. At least in my world.
    Why is he in the hospital? Did he trip walking out to his car and sprain his ankle? :D :p




    One can only assume conduit. It is certainly feasible.
    Since we have yet another MIA thread starter :mad: we may never know.
     
  14. Dec 13, 2009 #14

    JoeD

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    This is not correct. The only time current flows on the neutral is when you need 120 volts. 240 loads even if they are reactive or inducutive will still cancel each other out. A 240 volt welder is very reactive and it has no neutral.
     
  15. Dec 14, 2009 #15

    Nestor_Kelebay

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    Let me get back to you on this point, Joe.

    My understanding is that people often presume there can't be any current through the neutral wire because it's connected to ground in the main panel. So, if it's grounded at the panel then it supposedly has zero voltage, and therefore can't have any current. But, ask any dairy farmer, and you'll find out about "dirty electricity" where there are voltages and currents in the neutral wire that interfere with their operations. There can be enough voltage in supposedly neutral wires to cause cows to stop giving milk because of the tingling they feel from the very small shocks they get. I'm gonna phone down to the Electrical Engineering Department at the U of M tomorrow and ask what would happen in the neutral wire if there were an inductor connected between the black and neutral and a capacitor connected between the red and neutral.
     
  16. Dec 14, 2009 #16

    Nestor_Kelebay

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    Joe:

    The University of Manitoba doesn't have anyone who knows anything about house wiring except the electricians employed there.

    I talked to one major electrical contractor this morning and he tells me it's common to have current through the white wire. When they wire electrical outlets for kitchens, they will often cut the tab between the two outlets on a duplex receptacle and connect one outlet to the black voltage source and the other to the red voltage source. They do that because it's common for people to blow fuses or trip the breaker to the kitchen electrical outlet because so many things that get plugged in there draw high current (coffee maker, toaster, microwave, electric frying pan, etc.) So, by providing two 15 amp circuits to that outlet and sharing the neutral, you don't blow as many fuses, but any imbalance in the current ends up going down that shared neutral. If a toaster and blender are plugged in, you might have 10 amps through the toaster and 3 amps through the blender, and the difference of 7 amps will flow through the neutral. However, that same electrician told me that even through there is 7 amps in that neutral, there won't be any voltage in that white wire, and that violates the first principle of electricity. You simply can't have current without a voltage to drive it.

    That electrical contractor suggested I talk to one of the instructors at Winnipeg's Red River College where they train electricians, and I did so. I could tell that instructor simply didn't know enough about the subject to have any confidence in his answer, and he suggested I talk to the engineering department at Manitoba Hydro.

    Manitoba Hydro employees get every 2nd Monday off, and that just happens to be this Monday. I will talk to Manitoba Hydro's engineering department tomorrow.

    Anyhow, I fully understand that such an "imbalanced load" (as described for a kitchen outlet) is not exactly what we're talking about. What we're talking about is a current and voltage in the white neutral wire due ENTIRELY to the red and black voltage and current sine waves not cancelling each other out.

    I remain convinced that if those red and black sine waves don't cancel out completely, then there simply has to be a resulting current and voltage in the white wire. There's simply no other option. I'll talk to Manitoba Hydro tomorrow.
     
    Last edited: Dec 14, 2009
  17. Dec 16, 2009 #17

    Nestor_Kelebay

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    Phoned Manitoba Hydro today, talked to two electrical engineers and one electrical engineering technologist, and none of them knew that residential power consisted of two hot wires and one neutral wire with the two hots out of phase by 180 degrees. The technologist had no idea who to even refer me to. One engineer was willing to help, but didn't know that power was delivered via two hots that were 180 degrees out of phase. The other electrical engineer, a supervisor of the department was asking more questions than me... why do I want to know this, what difference does it make, who am I doing this for, etc. etc. etc. Then he just lost interest in the discussion and told me he didn't know the answer and didn't know of anyone who might.

    This is getting stupid already. The question isn't difficult, and I'm amazed that no one at Manitoba Hydro is knowledgeable about this.
     
  18. Dec 17, 2009 #18

    triple D

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    Stop whipping this horse!!!! The only thing in an oven using a neut. is the light bulb, or timer, or cooling fan. The neut is simply not required by code, anywhere, to match current carrying conductor size. Refer to quote in speedy's post.
     
  19. Dec 17, 2009 #19

    travelover

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    Well, I'm not surprised considering that they don't even know that hydro means water and electricity is - well, electricity. :D
     
  20. Dec 17, 2009 #20

    Nestor_Kelebay

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    Oh ye of little faith! Be patient.

    I am confident that I understand reactance well enough that if you have an inductive load on one leg of 220 volt house wiring and a capacitive load on the other leg, then where the two amperage waves meet at the white wire, there won't be complete cancellation, and there will be some NET amperage in the white wire.

    The issue I'm having now is that the voltage sine wave HAS TO BE affected by the inductor. If it wasn't, then the voltage sine waves would cancel completely, and I'd be standing here saying that there's a net amperage in the white wire WITHOUT any associated driving voltage in that white wire. (and, like, hey man, you can't have current without a driving voltage) If there's smoke there fire, and if there's current, there's voltage.

    So, that's where things stand right now. One of these days I'm gonna take a drive down to the U of M.

    PS: The horse tells me that he's wanting to know the answer too. The horse tells me he's always understood that the current sine wave is affected by impedance, but agrees that the voltage sine waves can't cancel completely cuz then you'd have current without voltage. He's a smart horse.
     

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