Does a 240v dryer plug need to be GFCI?

Discussion in 'Electrical and Wiring' started by InTooDeep, Jul 26, 2014.

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  1. Jul 26, 2014 #1

    InTooDeep

    InTooDeep

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    My laundry room right now is setup with the washer beside the dryer and then a laundry sink beside the dryer. I've been researching whether this is a problem having a sink close to a 240v outlet but can't find anything that says this is against code. The only thing I've found is that 120v outlets need to be GFCI.

    Firstly is this correct that 240v in a laundry room does not require GFCI when close to a sink. And secondly, if this is true, why?

    My basic logic would make me think that 240v is more dangerous than 120v.
     
  2. Jul 26, 2014 #2

    Wuzzat?

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    "The GFCI sensor in a two-pole QWIK-GARD circuit breaker continuously monitors the current flow in the two ungrounded ``hot`` load conductors and the neutral conductor. The sensor compares the current flow in all directions."
     
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  3. Jul 26, 2014 #3

    InTooDeep

    InTooDeep

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    So dryer outlets are automatically hooked up to prevent ground faults?
     
  4. Jul 26, 2014 #4

    Wuzzat?

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    With double insulated appliances with a two prong plug there supposedly cannot be a ground fault.

    With grounded appliances with a three prong plug the ground conductor carries virtually all of the fault current, and your body virtually none, since the resistance of your body is much higher than copper wire.

    With ungrounded appliances and a ground fault and 120v to ground your body is assumed to pass up to 1/4th amp to ground, giving a skin/body/skin resistance of 120/(.25) = 480 ohms.

    With ungrounded appliances and a ground fault and a GFCI your body will pass some current for a short time.
    How much time? Max T in seconds = (20/I)^1.43, with I in milliamps (UL 943). 20 mA is about the max let-go current and you will be disconnected in <1 second.
    For 10 mA, it's 2^1.43 seconds. You have a scientific calculator? My spreadsheet says this is 2.7 seconds.

    You can check for GFCI protection.
    Run a small 120v incand. bulb from either hot line to a known good ground. If it goes out and you hear a click somewhere in your house then you have it and then you need to reset the thing.
     
    Last edited: Jul 26, 2014
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  5. Jul 27, 2014 #5

    JoeD

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    The simple answer to the question is, NO you are not required to GFCI a 240 dryer receptacle.
     
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  6. Jul 27, 2014 #6

    Wuzzat?

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    Because the 120v dryer motor may cause nuisance trips?

    Sorry for spreading bad advice from other sites (if your dryer has a grounded frame)

    "
    Proper Application of Qwik-Gard GFCIs
    • Do not connect to electrical ranges or clothes dryers whose frames are grounded by a connection
    to the grounded circuit conductor.
    "

    from
    http://www.grainger.com/ec/pdf/QO-QOB-Miniature-Breakers-Catalog-2008.pdf
     
    Last edited: Jul 27, 2014
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  7. Jul 27, 2014 #7

    speedy petey

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    No.

    1) Older 3-wire dryers and ranges used the neutral ground the frame of the appliance. This is an instant GFI trip.
    2) It is simply NOT required.
     
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  8. Jul 27, 2014 #8

    speedy petey

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    Because it is highly unlikely that you'll pick up your dryer and drop it in the sink.

    The whole water vs. electricity thing while not a myth, is over-hyped. Those of us that like our water hot and our clothes clean are pretty happy about water and electricity mixing.
     
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  9. Jul 27, 2014 #9

    Wuzzat?

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    Assuming you are grounded and touch one hot wire you will never see more than 120v.

    I'm curious whether the fatality rate (1700/yr in the US) is any higher in countries that routinely use 220v/240v. They may be more careful than we are and so the danger cancels out.

    If there is any benefit to having a GFCI that is compatible with your dryer,
    or if any market exists for such a device
    and if false trips can be minimized,
    you might want to get one installed.

    My washing machine has a grounded plug but I ran an extra ground wire to the outlet screw. Virtually no cost to me, and added safety due to redundancy.
    I guess that is also an option for you, and cheaper than a GFCI.
     
  10. Jul 28, 2014 #10

    Wuzzat?

    Wuzzat?

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    Having dry skin when contacting residential voltages can save your life. Not so above 600v.
     
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  11. Jul 28, 2014 #11

    speedy petey

    speedy petey

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    That goes without saying. Then again it does not really apply to a site called houserepairtalk.com.
     
  12. Jul 28, 2014 #12

    Wuzzat?

    Wuzzat?

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    Straw man argument, minus 10 points! :(

    Facts cancel out hype.

    In your case it seems to need saying.

    Having information is a dominant strategy, as is carrying a weapon. You have it if you need it but you don't have to use it.

    "strategic dominance occurs when one strategy is better than another strategy for one player, no matter how that player's opponents may play."

    In this case the 'opponent' may be a non-functioning appliance. For the >600v cases, electronic air cleaners and CRT TVs come to mind.

    And knowing this info doesn't do any harm. Not always so with genetic testing info.

    My regards to Jim Port. :D I don't think his problems are genetic! :D :D

    Loosen up, SP. . . sooner or later you will catch me making a real error -
    and picking nits will probably blind you to that error when it does occur.
     
    Last edited: Jul 28, 2014
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  13. Jul 28, 2014 #13

    speedy petey

    speedy petey

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    You are one strange a$$ dude, you know that?
     
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  14. Jul 28, 2014 #14

    slownsteady

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    every family has one....or more :D
     
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  15. Jul 29, 2014 #15

    Wuzzat?

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    Last edited: Jul 29, 2014
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