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Thread: 240 v install

  1. #1
    DIY Senior Member rockycmt's Avatar
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    Default 240 v install

    have in the past properly installed 20 Amp 120vac circuits to my main. I feel I have a good understanding as to how they work and are installed. I am going to attempt my first 240vac circuit for a new range. My existing range is electric but the wiring is old and since I have the wall open I have the chance to put in new. Here are the details of my new range.

    Electric Supply:
    These ranges must be supplied with 208/240 volt,
    60 Hz., and connected to an individual, properly
    grounded branch circuit protected by a circuit
    breaker or time delay fuse (50 amp for 48" ranges,
    30 amp for 36" and 30" ranges). The receptacle
    must be a NEMA 14-50R device to accept the
    4-prong plug supplied with the range.

    The range is equipped for use with an electrical
    supply which uses a separate grounding conductor
    (4 wire system).
    If this range must be connected to an electrical
    system which utilizes a single conductor for ground
    and neutral (3 wire system), the grounding jumper
    at the terminal block must be connected.
    The grounding jumper is located to the right
    of the terminal block.

    The model I have is a 30 inch so I need a 30 AMP circuit. Here are my questions

    1- Why donít I need a ground on a 240 V circuit?
    2- When I install a 14-50R outlet can I put 30 Amp wire to it ?(This sounds wrong.)
    3- What is the correct gauge I should use to hook this up?

  2. #2
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Default

    1) See where it says "IF"?
    Yes, you DO need a dedicated ground and separate neutral. A 14-50R is a 4-prong receptacles that requires four conductors. This is a "120/240v" circuit, NOT a "240v" circuit.

    2) Yes, it would be wrong, but not non-compliant. Odd, I know. I would make sure the cord was indeed a 50A range cord.

    3) If you use a 30A breaker you can use 10/3 w/ground cable. If you are going with the 50A use 6/3 w/g cable.
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

  3. #3
    DIY Senior Member rockycmt's Avatar
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    Great comments I will go with the 50 A solution
    But....
    What is the difference between 120/240 and a 240 v circuit?

    And i guess if one had to use 3 wire hookup the jumber lets the neutral and ground piggyback back to the main?

  4. #4
    Electrician Johnny C's Avatar
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    Default 240-V Range Installation

    DO NOT install a 50 ampere breaker for a range that is listed to be used with a 30 ampere overcurrent device. Remember the wiring in the electric range is designed to be used with a 30 ampere overcurrent device, NOT 50 amps. This would be a violation of NEC Section 110.3(B). When the testing laboratory tested the electric range, it was tested with a 30 ampere overcurrent device. A fault in the wiring or heater element would result in a greater fault current and arcing than allowed by the testing Laboratory specs.

  5. #5
    DIY Senior Member rockycmt's Avatar
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    Default

    So are you saying go with 10/3 wg 30amp braker to a 14-50R outlet?

  6. #6

    Default

    Most standard 30" ranges require a 40 amp circuit (8/3 NM)


    I would at least install that in case someone wants a standard range there someday. Use 8 wire and a 30 amp breaker to stay within the Mfg's requirements on the one you are looking at.

    In the olden days, ranges were straight 240 volts (like your water heater still is today). No 120V components, so no neutral required. Newer models use 120V for controls, low heat. lights etc
    Last edited by 220/221; 12-11-2008 at 02:26 PM.

  7. #7
    Plumber jimbo's Avatar
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    Default

    Quote Originally Posted by 220/221 View Post
    Most standard 30" ranges require a 40 amp circuit (8/3 NM)


    Agree with that. I took a quick scan through my GE catalog, and all their 30" ranges spec. at 40 amp supply.

  8. #8
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Rocky, is this a "dual fuel" range? They typically call for a 30A circuit.
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

  9. #9
    DIY Senior Member rockycmt's Avatar
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    Yes this is a professional GE Monogram Duel Fuel range.

  10. #10
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by rockycmt View Post
    Yes this is a professional GE Monogram Duel Fuel range.
    Ah-ha! That would have been good to mention.
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

  11. #11
    Licensed Electrical Contractor Speedy Petey's Avatar
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    I agree with 221. Wire the circuit with 8/3nm cable but use a 30A breaker and receptacle. This way you have the opportunity to use an electric range later. The difference between #8 and #10 is no that much.
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

  12. #12

    Default

    Why don't you just use the information from the electric range data plate and size the circuit accordingly like you are suppose to.

    You will need see what the rated wattage is of the appliance and its nominal voltage.

    Everything else is just a guess.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  13. #13

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    I agree with 221
    Ok.....this is starting to freak me out

  14. #14
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by 220/221 View Post
    Ok.....this is starting to freak me out
    You too huh?
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

  15. #15
    Electrical Contractor jbfan74's Avatar
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    Quote Originally Posted by Speedy Petey View Post
    You too huh?
    What is up with you two?
    I'm evening freaking out!
    Yes I am A Pirate-Jimmy Buffett

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