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Thread: Wiring question

  1. #1
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    I recently disconnected a hot tub (replacing it with a green house) and I want to use the same dedicated circuit to power the greenhouse equipment.

    Only problem is, there is an extra wire! I have a red and a black wire that are connected to the juction box, a green wire that is grounded, but there is also a (much thicker) white wire was (if I remember right) wired directly to the tub (by passed the junction box entirely).

    What the heck is this white wire?

    What would I do with it if I wanted to wire in an outlet?

    Thanks for any help! I can post a pic of the juction box if it would be of any help...
    17 Nash Rd.
    North Salem, NY 10560

    YOU! Outta my gene pool!

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    Moderator Joseph Clemens's Avatar
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    The white wire is the Neutral -- It must be connected to any equipment that only uses 120 VAC. The black is a 120VAC hot line and the red is the other 120VAC hot line, together they provide 240VAC to equipment that uses 240VAC exclusively, in those types of equipment the neutral is not needed, just the two hot lines and the green - ground. In any equipment that uses 120VAC for any component, the neutral is needed to complete the 120VAC circuit.

    In other words for 240VAC equipment the 240VAC flows (both ways) through the black and red wires, but in 120VAC equipment the white - neutral wire is needed to complete the 120VAC circuit and allow the current to flow (to and from the source).

    In your case the white wire is probably larger than either hot wire because the hot tub likely had both 120VAC and 240VAC devices operating in it. Though the 240VAC devices may have used more power, it was delivered to them more efficiently at the higher voltage. 120VAC devices are somewhat less efficient and since there are two different "legs" of 120VAC, the red and black, they theoretically need the larger neutral to complete their path back to source since they are likely not balanced as 240VAC circuits would be.

    As you observed the white wire does not go through any switching devices, it, like the green or bare grounding wire must be continuous and never broken. Since it is used to complete any 120VAC circuits, when those devices are operating it carries current and is HOT.



    Joseph Clemens
    Tucson, Arizona, U S A

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    Cardiac Nurse JB_OrchidGuy's Avatar
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    I can attest hot tubs are 240. I had one as well, but mine had a 30 amp 240VAC breaker and a 20 amp 120VAC. The only thing that runs on 240VAC is the heater. Everything else runs on 120VAC.
    JB
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    SirKristoff is a poopiehead Ozzy's Avatar
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    OK MOVE OUT OF THE WAY AND LET THE ELECTRICIAN THOUGH.



    I agree with what was said here except for a couple of minor points.

    Quote Originally Posted by [b
    Quote[/b] ]The black is a 120VAC hot line and the red is the other 120VAC hot line, together they provide 240VAC to equipment that uses 240VAC exclusively, in those types of equipment the neutral is not needed,
    Not entirely true. By code the hot tub should be wired through a GFCI. (Ground Fault Current Interrupter). These devices are what's in most bathrooms with the red and black buttons. They keep you from getting fried if you drop the hairdryer in the tub. They are required anywhere that is within 6ft of a water source or outside. Since the hot tub is a water source it has to be GFCI protected. GFCI's require a neutral to work. There are other 240v objects that requires a neutral, Stove and Dryers requires a neutral.

    Quote Originally Posted by [b
    Quote[/b] ]n your case the white wire is probably larger than either hot wire because the hot tub likely had both 120VAC and 240VAC devices operating in it. Though the 240VAC devices may have used more power, it was delivered to them more efficiently at the higher voltage. 120VAC devices are somewhat less efficient and since there are two different "legs" of 120VAC, the red and black, they theoretically need the larger neutral to complete their path back to source since they are likely not balanced as 240VAC circuits would be.
    I really don't know why the neutral is bigger. There is no reason for it to be. I agree with most of what was said above. When you say power regarding electricity, you are not talking about voltage, you're talking about amps. A 240V device will use roughly half of the power of a 120V device. So that's what makes higher voltage more efficient. It's about the same as trying to drive a stake in the ground with a 16 oz hammer verses a 5lb hammer.
    You're right about the power from the two hot legs (Black and Red wires) traveling back on the same neutral wire. But the neutral wire only has to be rated the same as the hot wires. Even though it is carrying double the load. There is a very smart way this is done. (Thanks to Nikolos Tesla for designing a better electrical system than what Thomas Edison had) Look up "War of the Currents" Very interesting and it deserves it's own topic here. In the USA electricity is on 60 hertz. That means 60 times a second there is a pulse of electricity sent through the each wire. The hot legs alternate, meaning that there is never electricity on both wires at the same time. They take turns. So the neutral never has more power on it than a single hot leg, but it has twice the power because instead of it being 60 hertz it's 120 hertz. That's where the name AC (Alternating Current) comes from. The USA has a 3-phase system which is even more efficient than Single Phase 240V. It's is the same as I described above except there are 3 hot wires instead of two. This system is used for bigger buildings like stores, restaurants, office buildings, ETC.


    OK what was the original question? Oh yeah hot tub and greenhouse. Dave send me pics of where the hot tub wires come out and the hook up of the green house and I'll get you going in the right direction.

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    Moderator Schmoderator Fluorescent fluorite, England PlantAKiss's Avatar
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    Quote Originally Posted by [b
    Quote[/b] ]What the heck is this white wire?
    Any IDIOT would know what that wire is. Maybe you should pay somebody like an electrician to come out there and tell you what that wire is. After all...people that stupid SHOULD pay for being so stupid.

    "Fox terriers are born with about four times as much original sin in them as other dogs." - Jerome K. Jerome

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    SirKristoff is a poopiehead Ozzy's Avatar
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    I agree, I'll come take your money. Or you can pay me in Dave's firey sauce.

    And no Pak that is not what I meant.




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    Quote Originally Posted by [b
    Quote[/b] (PlantAKiss @ Aug. 15 2006,5:38)]
    Quote Originally Posted by [b
    Quote[/b] ]What the heck is this white wire?
    Any IDIOT would know what that wire is. Maybe you should pay somebody like an electrician to come out there and tell you what that wire is. After all...people that stupid SHOULD pay for being so stupid.

    Harsh...

    PAK, you need an "outlet" to vent that angst.
    There's a tunnel at the end of the light...

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    herenorthere's Avatar
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    This amateur will add that you should never assume anything when working with wiring in older houses. Just because a wire should be something doesn't mean it actually is. Remember that previous owners as incompetent as us each had an opportunity to really screw things up.

    Whenever there's any doubt, test and make sure wires are what you think they are. And there should always be doubt. It's amazing how often grounds aren't grounded. And definitely don't take my (former) shortcut of thinking it's safe to work downstream of a wall switch without tripping the circuit breaker. I got shocked that way once and figure someone must have switched the neutral instead of the hot wire.

    Since I'm not methodical enough for my own good, I've pretty much quit doing wiring and I long ago gave up the illusion of doing plumbing.
    Bruce in CT

    Madness is something rare in individuals but in groups, parties, peoples, ages it is the rule. Friedrich Nietzsche

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