4 wire dryer outlet or 3 wire?

[Escapades]

In new residential housing, running a 10/3 nm romex to a dryer is a 3 wire or 4 wire outlet and cord required.
Mike

 

[goldstar]

Most of the new dryers on the market today require 4 wire connections. You should always make the choice to run 10/3 rather than 10/2 anyway. If it turns out that the dryer requires only a 3 wire connection then you don't use the neutral. However, if it requires a 4 wire cord and plug attachment and you only ran a 10/2, it could be more difficult to run the new line in after the walls are up and finished.

 

[Jim W in Tampa]

You were never allowed to use 10-2 for a dryer.What was permitted was to bond the frame to the neutral and not have a ground wire.Code now requires 4 wire

 

[busman]

At one time, you could use 10-2 SE cable for a dryer and bond the neutral to the frame of the dryer. The only way 10-2 romex would be legal is if the dryer had a 240 volt motor, then no neutral would be required and 10-2 with a 3 prong grounding plug would be correct.

Mark

 

[pierre]

250.140 is the reference. The exception permits existing (exisitng before the code rule change) dryers to be of the 3-wire type. Otherwise the dryer is required to be installed with a 4-wire, using a 4 conductor cord. The manufacturers do not sell the unit with a cord, as they do not know if the sale will go to a building with an existing receptacle or a new building.

 

[charlie b]

250.140 is the reference. The exception permits existing (existing before the code rule change) dryers to be of the 3-wire type.

The rule does not govern the dryer itself; it governs the receptacle outlet. An existing 3-wire outlet need not be replaced with a 4-wire outlet. I am sure that is what you meant to say.

 

[pierre]

Thanks Charlie... maybe I should have you proof read my posts. 8)

 

[jeff43222]

The OP mentioned new residential housing, so the only legal way to wire the circuit is to use a 4-prong receptacle. The dryer would then need to have a 4-conductor cord-n-plug installed.

 

[chicar]

A lot of people don't know that the dryer is 2 110v c1rciuts. One for the 110v motor and one for the heating element. The 3 prong plug needs a neutral, not a ground. The 4 prong gets a ground wire.

 

[don_resqcapt19]

chicar,

A lot of people don't know that the dryer is 2 110v c1rciuts. One for the 110v motor and one for the heating element.

Mine has 240 volt heating element and I just looked a number of online wiring diagrams that all showed 240 volt heating elements and 120 volt motors and controls.
Don

 

[chicar]

Don. I graduated appliance repair class in 1977. The dryers I worked on had 110v heaters. Our first lesson was to check for wiring diagrams. Wether the heating element was then 110v,or now 220v, you still need a neutral [old] or grounded.[new]

 

[Jim W in Tampa]

Also at issue is the light that some have as well as the timer motor.While i am guilty of using 10-2 romex 20 years ago i do know now why it was wrong.What really upsets me is that an inspector noticed it and still passed it.How many of you know why up untill about 10 years ago we permitted 3 prong for ranges and dryers and why it was allowed to start with ?

 

[chicar]

I think back then they considered grounded and grounding pretty much the same. Then one day someone touched the dryer while the other hand was submersed in the laundry sink water and said, # * @ # .

 

[don_resqcapt19]

chicar,

Then one day someone touched the dryer while the other hand was submersed in the laundry sink water and said, # * @ # .

The change to delete the 3 wire circuit and require the 4 wire one took at least 5 code cycles. In all of the proposals and comments, there was not one documented case of a shock or other problem caused by the use of a 3 wire circuit.
Don

 

[Jim W in Tampa]

chicar,

Then one day someone touched the dryer while the other hand was submersed in the laundry sink water and said, # * @ # .

The change to delete the 3 wire circuit and require the 4 wire one took at least 5 code cycles. In all of the proposals and comments, there was not one documented case of a shock or other problem caused by the use of a 3 wire circuit.
Don

I had one case in my over 20 years.What happend was a defective range surface mount outlet.It was not making a good connection to the cord netral.Luckily the lady that was pregnant at the time was ok,had her or the baby been hurt a company brand name that starts with E would been in court.Give you all a hint it started during world war 2

 

[benaround]

10-2 was allowed for a short time,when the code said a 'covered' neutral was ok. Shortly thereafter the term changed to ' insulated' but the tradition carried on.

 

[benaround]

The only dryers I have ever seen with 120vac heating elements, are the little stackable ones the rest all have 230vac heat.

 

[chicar]

Received a service call. Lady would get shocked when hand in sink and touch microwave while on. Removed three prong receptical from wall. Someone jumpered the grounding screw to the grounded screw just to fool the inspector. I removed the jumper wire,installed g.f.c.i.,install the sticker,done.

 

[Jim W in Tampa]

Received a service call. Lady would get shocked when hand in sink and touch microwave while on. Removed three prong receptical from wall. Someone jumpered the grounding screw to the grounded screw just to fool the inspector. I removed the jumper wire,installed g.f.c.i.,install the sticker,done.

Ok just what do you think you helped ? What you did was a violation in my opinion.You now have a piece of equipment that requires equipment ground.While she wont get killed what you did wasn't good fix

 

[don_resqcapt19]

Jim,

Give you all a hint it started during world war 2

That was investigated by Bennie, and he could find no evidence that the use of a single wire for both the grounding and grounded conductor had anything to do with WW2.
Don