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Electrical Code - USA Commercial or Residential 1999 / 2002 / 2005 versions - for UNITED STATES

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  #1   IP: 173.67.122.2
Old November 28th, 2009, 10:02 AM
hzolla hzolla is offline
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Default Convert Dryer Circuit to 120V

I am replacing an electric dryer with a gas one. I had a licensed plumber install the gas line so it is ready to go.

I need a grounded 120V receptable for the gas dryer. The existing circuit is 240V and I want to reuse the cable between the panel and the receptacle and downgrade it to 120V.

Here is my problem:
The existing 240V cable does not have a groound - it is an old type that has three conductors, white (N), black (H) and red (H).

And my question:
To put in a grounded 120V outlet, what is the risk of using the red conductor as my new ground so I don't have to install a new run? Should I label the red conductor "ground" in the panel box and in the receptacle box? Should I just strip all visible red insulation from it so that no one in the future gets confused?
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  #2   IP: 70.195.0.188
Old November 28th, 2009, 10:41 AM
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Wgoodrich Wgoodrich is offline
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If the house is properly wired you have 1500 va already in the laundry room for the laundry equipment. Why not just plug into the washer receptacle for your gas dryer and leave the dryer receptacle existing ?

Wg
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  #3   IP: 173.67.122.2
Old November 28th, 2009, 01:41 PM
hzolla hzolla is offline
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Thanks so much for writing back so quickly. I just moved in to this house so I am stuck with what is here.

According to the nameplates on the new washer and dryer, they each are listed at 120 V, 15A. Please tell me if I am wrong about this, but I don't think it is OK to plug both these in on the same 15A or 20A circuit.

The existing washer receptacle is on a 20A breaker, grounded and is OK. It is not a dedicated circuit, it is shared with other receptacles and lights which are nearby.

The reasoning behind this project is that I believe (perhaps incorrectly) that the dryer needs to be on another circuit.

-HGZ
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  #4   IP: 173.67.122.2
Old November 28th, 2009, 02:04 PM
hzolla hzolla is offline
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Default More Info

Upon further inspection, I realize the dryer outlet is grounded, though not through a conductor which is run with the power cable. It appears a bare conductor was run some other way (I can't see very far into the wall - perhaps it is from the nearby washer receptacle) to the dryer receptacle and is connected to the (metallic) box which contains the receptacle. I tested it to see whether it is bonded to the neutral and it has a resistance of 1.3 Ohms.

I know you would never do this if you were installing this today. However, is this considered OK?

What is the best course of action here?
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  #5   IP: 72.38.178.108
Old November 28th, 2009, 03:34 PM
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Recheck the specs. A washer does not draw 15 amps. Does it say use on a 15 amp circuit or the current rating is 15 amps.
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  #6   IP: 98.247.156.18
Old November 28th, 2009, 03:34 PM
suemarkp suemarkp is offline
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I'd read further into the nameplate ratings on the washer and dryer. I've noticed many appliances saying "15A 120V", where what they're really telling you is that is what the plug is and circuit needs to be. Does anything list the amps, VA, or watts used? A 120V gas dryer typically only uses about 6 amps and the washing machine perhaps up to 10. I think they'll be fine on a 20A laundry circuit.

If you can't verify the integrity of the separate grounding wire for the dryer circuit, I wouldn't use it. Measuring the resistance is not a good test. It may be < 1 ohm with the meter with a few little wire fuzzies making good contact. Get a fault down that circuit, and the wire could burn open and have infinite resistance.

If you really don't want to use the existing 120V laundry circuit, I'd be inclined to remark the red wire green (both in the receptacle box and in the breaker panel). This is only allowed if the wire is in a cable and not individual conductors. Obviously, that remarked wire would need to be removed from the circuit breaker and moved to the grounding bus. You'd also have to change the breaker to 20A (single or double pole), and you'll probably need #12 pigtails on the receptacle because the #10 wires probably aren't going to fit the screws.
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  #7   IP: 71.174.88.209
Old November 28th, 2009, 04:55 PM
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scuba_dave scuba_dave is offline
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My washer pulls about 7a I think.....
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  #8   IP: 173.67.122.2
Old November 28th, 2009, 05:53 PM
hzolla hzolla is offline
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Smile Done

I agree that the nameplates are probably bogus. Though both instruction manuals call for a dedicated circuit for each. I would imagine that the washing machine, since it has a heating element and a motor probably draws more peak current than the dryer.

I followed Mark's (and a local electrician friends's) advice - I wrapped the red conductor in green electrical tape and used it as a ground. I now have a dedicated 20A 120V circuit for the dryer. I needed to get this done this weekend and not mess around.
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  #9   IP: 98.247.156.18
Old November 29th, 2009, 10:38 AM
suemarkp suemarkp is offline
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Your washing machine has a heating element? Never seen that before except in a dish washer -- usually the hot water input hose is sufficient.

I hate all the manufacturer instructions which require a "dedicated circuit". Completely bogus for many things, but that label is one way to put a 15A plug on a device which has a nameplate larger than 12 amps. Saying "use on 20A circuit" would be better, but not sure UL would go for that without a 20A plug (which will greatly reduce where you can plug the item in since hardly anyone install 20A T slot receptacles).
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  #10   IP: 173.67.122.2
Old November 29th, 2009, 04:30 PM
hzolla hzolla is offline
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Default Many high end washers have heaters and steam cycles now

Here is info on the washer:

http://www.whirlpool.com/catalog/pro...arch=wfw9500tw

The latest greatest thing these days is a steam cycle (both the washer and dryer have them) which necessarily requires some sort of heater.

In addition, in order get the highest energy star rating (which this unit has) it uses a small amount of water and uses an internal heater to keep it at the wash temperature throughout the long cycle. Intead of an agitator which rubs the clothes back and forth against each other, these high efficiency front loading washers tumble the clothes in and out of a pool of wash water for a long period of time which is gentler on the clothes and uses less net energy.
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