Lady Kenmore Solid State Dryer

[combo52]

Grounding 208 and 240 volt ranges and dryers In The US

Grounding ranges and dryers has always been very important for safe operation of these appliances.

 

This 1979 LKM electric dryer was built with the white neutral wire tied to the cabinet in the wiring harness from the factory, you can confirm that the ground connection is properly connected by taking an Ohm meter and testing from the El shaped prong on the cord to the cabinet of the dryer and you should have 0 Ohms resistance.

 

The current requirement to have 4 wire cords which provide a separate ground wire all the way back to the service panel is a mixed blessing IMEO.

 

The problem with a 4 wire cord is you have no way of knowing whether the appliance is ACTUALLY grounded and whether it STAYS grounded throughout its use in your house. We see appliances all the time where the ground was never connected either at the appliance, in the outlet box or in the circuit panel.

 

With the 3 wire system where the neutral and ground are the same the dryer will not even run if the neutral-ground goes open, the possible bad part of this system is the cabinet of the appliance can become live with 120 volts, but you will have to call for service to get the dryer to run again.

 

In my homes and at the warehouse I never use the 4 wire system, first of all it is a waste of copper as you are using 25% more copper [ or aluminum ] because you have an extra 10-6 Ga wire running all the way from the appliance to the main panel that will never be used to run the appliance.

 

John L.

 

[qsd-dan]

That was an interesting post, John. Thanks

 

[maytag85]

I never really understood what the point of the newer 4 prong 240 volt dryer cords. If they used 3 prong 240 volt plugs all these years and dryers that use them still work fine I don’t see what the point of putting a 4 prong 240 volt plug on them.

 

[vacerator]

Sean, same here.

I figure electricians and plumbers in their trades have conspired with local building code enforcers to make more money, and or more work for their members by improving the ground, and the chimeny flu liner diameter from 3, or 4 to 6 inches for gas water heaters. Expensive jobs. So if a 3 inch diameter flu was adequate for 80 years, and our grandparents never had asfixiation, or electrocution problems, why now? As usual, do the math, follow the money.

 

[kb0nes]

The point of the 4th wire is that a safety ground wire should never carry circuit current unless there is a fault. But indeed the ground and neutral are bonded in the service entrance panel so the chassis of the appliance should never be far from ground potential. That is UNLESS the neutral connection breaks then at which point the chassis flies off to 120v AC to ground. This can't happen if there is a 4th ground wire as the breaker will trip.

But John's point of the possibility of having an open ground wire is valid, and unless someone insures the ground integrity one might be simply hoping that someone did things right. Unlike 120v outlets I am unaware of a common plug in outlet tester for a 240v dryer outlet.

 

[mattl]

Larger flue?  Mine was downsized years ago when I went to a 96+ furnace. Was told since it was only the WH there was too much draw so they dropped a flex line to reduce it, not a big deal, took less than an hour.

 

[vacerator]

Good tip Matt;

Hope I won't need one then when our WH needs replacing. Had this one since 2002. We only keep it just above warm for the two of us, so likely why it's still good. 40 gallon GE smart heater 12 year. Already have a 95+ furnace.
It was my Dad's house when the flu enlargment was required. He had an 80% efficiency Heil furnace that was still using the chimney for exhaust. Only drew in outside air for combustion. There was no liner yet. Of course, a year after he passed my sister had to replace it. She had central air installed 2 years prior and they said the furnace was still ok. Heat exchange was perforated clean through. Her Co2 detector went off, but ironically she smelled it first.

 

[historian]

Ground lug

Hey, I am NOT a professional but wouldn't this green lug be where you would connect the 4th wire?

 

[combo52]

Ground Connection On An Electric Dryer

Hi Historian, Yes that is where a separate ground wire gets connected, either from a 4 wire cord or a separate ground to a cold water pipe etc.

 

But if you are going to install a 4 wire cord on an older WP-KM dryer like this you need to raise the dryer top and disconnect the internal ground that goes from the white center terminal to the cabinet.

 

John L.

 

[historian]

Thanks, good to know!