Expert: Greg Hughes - 5/10/2007

Question
QUESTION: My dryer is a newer 4 prong model.  My old outlet is only 3 prong.  I bought a 4 prong outlet.  But I only have a black, white, and copper wire coming to the old outlet.  Where do I get the 4th wire from?  Do I need to re-wire through the wall from the panel box?
ANSWER: Hi Matthew,

You are one of the many that got caught in the changes the NEC made to homes.

Many people don't understand that dryers use both 220v and 110v. In fact it has misstated here at this site that you don't need the neutral for dryers.

Some European appliances are true 220v, but here in the U.S.A. most appliances use 110v for the clocks, timers, and motors.

So following the NEC, the appliance manufactures went back to the 4 prong cords for 220v appliances that use 110v.

Here is why you need the neutral and ground;

If you wire your dryer with 3 wires being hot, hot, and ground, then the load bearing neutral has to travel on the ground wire. This makes your ground wire "load bearing".

If you wire your dryer with 3 wires being hot, hot, and neutral, then you don't have that ground protection.


Now, to your question "do I need to rewire?"

Honestly, to be protected the best you can possibly be against shock, then yes you do.

Basically, you need a neutral wire ran to your dryer. How that happens depends on the setup of your house circuits.

I know that there are sites that describe how to rewire your dryer so that the 3 prong cord works, but I strongly do not recommend it because you are bypassing a safety feature.

Hope that makes sense. If you have more questions just let me know.

---------- FOLLOW-UP ----------

QUESTION: what if I take the ground wire coming out of my wall and use that as the neutral?  Then I go to my panel box and move the ground wire to the neutral bar.  Maybe put white tape on it and label it.  Then I take a short wire and wire that from the outlet ground to the metal conduit box?

This way I'm not really pulling wires through the 2x4's in the wall.  Would this work?

Answer
Matthew,

There are websites that describe how to convert your dryer from a 4 prong to a 3 prong.

I do not recommend losing your ground, which is what you would be doing by what you described.

We have been using 3 prong outlets for years. I have worked for the big major appliance companies and never ran into a problem using a 3 prong outlet.

Apparently the bigwigs at the NEC decided that this is a large enough problem to change the code.

However, since the dryer came with a 4 prong I am not inclined to endorse you changing it unless you have written consent from the manufacture.

But there are websites that describe how to install a 3 prong cord.


Hope this helps