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  1. #1
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    Default changing 3wire 240v to 4wire 240v

    I have a hot tub the requires 4wire (2 hot, ground, neutral). My house has a quick disconnect that's wired 3 wire (2 hot, ground). I have NO way to get a single wire back to the main box to use as a neutral. Any solutions? I was thinking of changing the quick disconnnect out and putting in a new box that wouls let me run a neutral to it. Will this work? Any other solutions would be greatly appreciated.

  2. #2
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    Default Re: changing 3wire 240v to 4wire 240v

    I'll have to plead ignorance, I have never heard of using a quick disconnect on a house. Normal house wiring from a power company to a house is 3 wire, 2 hot and one common. The common is reference to ground. The wiring goes from a transformer to a Meter base and then to the main breaker box. A ground rod is installed near the house and the ground wire is run from it to the breaker box and is connected to a bus that is used to connect all grounds and the common wires for 120 volt circuits. At least thats the case in the U.S..
    Jack
    Last edited by JLMCDANIEL; 06-30-2008 at 11:02 PM.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
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    Default Re: changing 3wire 240v to 4wire 240v

    I must be getting old YukYuk, I thought he meant the power to the house was a quick disconnect. Need to read a little bit slower.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  4. #4
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    Default Re: changing 3wire 240v to 4wire 240v

    kandpwood, you might want to take a look at this post http://advice.thisoldhouse.com/showthread.php?t=6680. I am not familiar with code requirements for hot tubs, Ravens53 solution in the referenced thread may apply to your circumstance but you should check with your local building dept for confirmation.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
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    Thumbs up Re: changing 3wire 240v to 4wire 240v

    Quote Originally Posted by JLMCDANIEL View Post
    kandpwood, you might want to take a look at this post http://advice.thisoldhouse.com/showthread.php?t=6680. I am not familiar with code requirements for hot tubs, Ravens53 solution in the referenced thread may apply to your circumstance but you should check with your local building dept for confirmation.
    Jack
    The advise I gave in regard the oven is a different application.
    There is no short cuts in wiring a hot tub spa. you will need a 4 wire configuration 2 hots a neutral and a ground. The neutral carries the unbalanced load of the control circuits which can be less then a amp but 5 mil amps can kill you so hooking the ground and neutral together in this aplication can kill you. You also need to protect the conductors going to the hot tub with a GFCI breaker. You also must bond and metal parts on the hot tub. There is also verbage in the National electric code about distances of other power that must also be GFCI protected.

    If life means alot to you, your family members and friends Hire a liscensed electrician to do your install. This is not a job for a homeowner. Water Electricity just do not go together it resaults in DEATH
    Harry

  6. #6
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    Default Re: changing 3wire 240v to 4wire 240v

    Quote Originally Posted by Ravens53 View Post
    The advise I gave in regard the oven is a different application.
    There is no short cuts in wiring a hot tub spa. you will need a 4 wire configuration 2 hots a neutral and a ground. The neutral carries the unbalanced load of the control circuits which can be less then a amp but 5 mil amps can kill you so hooking the ground and neutral together in this aplication can kill you. You also need to protect the conductors going to the hot tub with a GFCI breaker. You also must bond and metal parts on the hot tub. There is also verbage in the National electric code about distances of other power that must also be GFCI protected.

    If life means alot to you, your family members and friends Hire a liscensed electrician to do your install. This is not a job for a homeowner. Water Electricity just do not go together it resaults in DEATH
    Thanks Harry as I said I'm have no experience with hot tubs or the requirements.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  7. #7
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    Default Re: changing 3wire 240v to 4wire 240v

    Quote Originally Posted by YukYuk View Post
    Jack,

    A quick disconnect is the emergency cut off required five feet from the 240 Volts Spa/hot tub; a fairly common term. It may be incorporated into/onto the Spa Disconnect GFCI Load Center if its shared placement permits or seperately located within the code required safety access zone.
    the conductors feeding the spa need to be protected by a GFI if the disconnect or control panel is located on the SPA.
    Harry

  8. #8
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    Default Re: changing 3wire 240v to 4wire 240v

    Quote Originally Posted by asc2078 View Post
    This is off-point for this thread but another application for using a disconnect in a residential installation is when the breaker panel is not located near the meter base. In a standard residential application, per our local code, the breaker panel is not supposed to be located more than 8 Ft. from the meter base. This is not always practical if the house has no basement and the electrical service drop comes in on an inconvenient side of the house.

    For example: At one house I wired, the overhead service drop came in from a pole on the side of the house that contained the master bedroom. Had I followed standard code, the breaker panel would have been located in a conspicuous spot on the wall of the master bedroom. By installing an outside disconnect below the meter base, the code allowed me to continue the entry cable, through the crawl space and locate the breaker panel at another location in the house.

    As I understand it, this disconnect requirement is related to fire safety. Under normal circumstances the fire department will know where the main electric service is in your house because the breaker panel is always close to the meter base. If the breaker panel is in a more distant location, they can simply throw the disconnect and kill all power in the building.

    DB
    The main reason in your case you stated is that it is considered unfused wire from the transformer to the main breaker. having unfused wiring running at great distances thoughout a home or any building would be very unsafe. I have seen the resaults of a phone installer when he drilled through the side of a home. The service cable was penitrated by his small drill shorted the service cable and burnt the side house before the transformer fuse blew.
    Harry

  9. #9
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    Default Re: changing 3wire 240v to 4wire 240v

    Quote Originally Posted by asc2078 View Post
    You are probably correct on that point because with that setup I referred to, one actually has two main breakers. One is in the outside box below the meter base and the other is in the electrical panel. That way if the line is shorted between the meter base and the more distant breaker panel, the outside main trips.

    DB
    I also want to point out the disconnect becomes the service. the second panel becomes a sub panel that would require a separate neutral and ground conductor service cable. The Neutral bar does not become bonded to the panel can. The ground bar does get bonded to the can. We were required to keep the unfused wire in the house at a minimum less than 5'.
    Harry

  10. #10
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    Default Re: changing 3wire 240v to 4wire 240v

    Years ago I ran No. 10 copper wire, three conductor (white, black and uninsulated ground) from the breaker panel to an electrical dryer which we still use.

    In the panel I connected the white wire to one side of a double pole breaker and the black wire to the other. The ground wire I connected to the ground bus. I'm pretty sure the service neutral is connected to the ground bus in the breaker box.

    The other end of the wires I connected to an electic dryer with the white and black wires going to the heating element and the ground wire to the metal case of the dryer.

    Is this a dangerous hookup? Should I have used a 4-wire conductor and somehow connected this at the dryer and breaker box end?

    I'm asking because the new wall oven I am thinking of connecting, came with instructions that say this:

    "The neutral of this unit is grounded to the frame through the green or solid grounding wire. (The green and the white wires are twisted together at the termination of the conduit.) If used on new branch-circuit installations (1966 NEC)...or in an area where local codes prohibit grounding through the neutral conductor, untwist or disconnect the green wire and connect the green wire to ground in accordance to local code. Connect the white neutral to the service neutral."

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