DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Electrical and Wiring > Does a 240v dryer plug need to be GFCI?




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Old 07-26-2014, 07:07 AM  
InTooDeep
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Default Does a 240v dryer plug need to be GFCI?

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.



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Old 07-26-2014, 07:17 AM  
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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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Old 07-26-2014, 10:27 AM  
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So dryer outlets are automatically hooked up to prevent ground faults?

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Old 07-26-2014, 11:36 AM  
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Originally Posted by InTooDeep View Post
So dryer outlets are automatically hooked up to prevent ground faults?
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.
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Old 07-26-2014, 06:13 PM  
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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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Old 07-26-2014, 06:22 PM  
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Originally Posted by JoeD View Post
The simple answer to the question is, NO you are not required to GFCI a 240 dryer receptacle.
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-QO...talog-2008.pdf
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Old 07-26-2014, 07:40 PM  
speedy petey
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Quote:
Originally Posted by Wuzzat? View Post
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-QO...talog-2008.pdf
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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Old 07-26-2014, 07:41 PM  
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Quote:
Originally Posted by InTooDeep View Post

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.
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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Old 07-27-2014, 11:09 AM  
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Quote:
Originally Posted by InTooDeep View Post
My basic logic would make me think that 240v is more dangerous than 120v.
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.
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Old 07-28-2014, 11:52 AM  
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Quote:
Originally Posted by speedy petey View Post
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.
Having dry skin when contacting residential voltages can save your life. Not so above 600v.


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