How to convert a 240V AC outlet to 120V AC outlet

Reply

  #1  
Old 05-08-15, 01:20 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
How to convert a 240V AC outlet to 120V AC outlet

Hello all,

I need to replace the 240V outlet with 120V outlet. Give the outlet comes with two types, one is four-hole and the other is three-hole. Here is my plan, can someone double-check whether my plan is correct?

In the case of four-hole 240V receptacle with a four-wire circuit,
1> In receptacle side, connect white wire to neutral terminal(silver), black wire to hot terminal(brass), and connect green/bare wire to ground terminal(green). Finally wrap the red wire and do NOT use it.

2> In the power panel, replace the 240V 20amp breaker with 120V 15 amp breaker. Then connect white wire to neutral bar, black wire to hot bar, and green/bare wire to ground bar. Finally wrap the red wire and do NOT use it.

In the case of three-hole 240V receptacle with a three-wire circuit
1> In receptacle side, connect red wire to neutral terminal(silver), black wire to hot terminal(brass), and connect bare wire to ground terminal(green)

2> In the power panel, replace the 240V 20amp breaker with 120V 15 amp breaker. Then connect red wire to neutral bar, black wire to hot bar, and bare wire to ground bar.

Thank you
 
  #2  
Old 05-08-15, 01:27 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
In the case of three-hole 240V receptacle with a three-wire circuit
1> In receptacle side, connect red wire to neutral terminal(silver), black wire to hot terminal(brass), and connect bare/green wire to ground terminal(green)
If you have a three wire receptacle you have black, white ground. That can be converted to 120v. If it is a dryer or stove you would most likely have black, white, red no ground. That can not be changed to 120 because a none of the colors can be used as a ground.
 

Last edited by ray2047; 05-08-15 at 02:27 PM.
  #3  
Old 05-08-15, 02:10 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Why do you said "If it is a dryer or stove you would most likely have black, white, red no ground. That can not be changed to 120 because a none of the colors can be used as a ground."

Why I cannot change the setting in the power panel and then I will have ground, neutral and hot. Three wires are all conductors and why I cannot use it for 120V?

Based on my understanding, a 240V outlet always has two hot wires and one ground. It may NOT have neutral wire. So I feel confused about your comments above.

Thank you
 
  #4  
Old 05-08-15, 02:19 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Almost all dryers and stoves are 120/240 not 240. At one time the NEC permitted a combined neutral ground using a white wire so no bare or green was used but for 120 you must have bare or green. (4-wire stove and dryer receptacles do contain a green and can be converted to 120v,)

National electric Code states that neutral wires and ground wires #6 and smaller must be factory colored green, yellow green, or bare for ground wires and neutrals white or gray. Other colors of #6 or smaller can not be field marked those reserved colors.
 
  #5  
Old 05-08-15, 02:22 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello ray,

Thank you for your quick response.

Here is the problem we have. The old outlet is 240V for electrical dryer.
Now we plan to buy gas dryer that requires 120V.

Question 1> Do you mean I cannot convert the power line from 240V into 120V?

Question 2> Do dryer and washer require separated breaker or they share one?

Thank you
 
  #6  
Old 05-08-15, 02:35 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Question 1> Do you mean I cannot convert the power line from 240V into 120V?
If there is no ground wire and it is wired with non metallic cable (AKA Romex) it can't be converted.
Question 2> Do dryer and washer require separated breaker or they share one?
Yes if you mean a gas dryer. Best practice it should be a dedicated 20 amp circuit. In some cases it may need to be GFCI protected.
 
  #7  
Old 05-08-15, 02:38 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
"If there is no ground wire and it is wired with non metallic cable it can't be converted."

In this case, when I hire a electrician, he has to route a new wire from the power box to my wash room.

Thank you


A related post:
http://www.doityourself.com/forum/el...it-change.html
 
  #8  
Old 05-08-15, 02:40 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
In this case, when I hire a electrician, he has to route a new wire from the power box to my wash room.
No, a new cable. This is usually an easy DIY job.
 
  #9  
Old 05-08-15, 02:47 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello ray,

What do you mean a new cable?
Do you mean I just need to add one #12 bare wire to supply as a ground?
In that case, I have to open the drywall that has been finished and it will be difficult for me to do it.

Can you give me some instructions in detail or point to me some places where I can find further information?

Many thanks!
 
  #10  
Old 05-08-15, 03:36 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
I have to open the drywall that has been finished
Why would you? You almost never need to open the drywall to run new cable. You either fish it from above or below. Conduit or surface raceway (AKA Wiremold) are two other ways. Give us details o where the dryer is and where the breaker box is and we can better help you.

While the NEC will allow you to run a single ground wire from the panel to an existing ungrounded receptacle that is not what you are doing. You are adding a new receptacle. In any event same rules for running a single ground wire as a cable so same amount of work.
 
  #11  
Old 05-08-15, 08:34 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello Ray,

Thank you for your great helps and I will report back after we close the house.

To summarize your points, here is my understanding:

In the all following cases, I can make the conversion from 240V to 120V.

Case 1> the 240V outlet has red(hot), black(hot), white(neutral), bare(ground)

Case 2> the 240V outlet has red(hot), black(hot), bare(ground)

Case 3> the 240V outlet has white(hot), black(hot), bare(ground)

The only case, I cannot make the conversion b/c it violates the code which says the ground MUST be bare wire:

Case 4> the 240V outlet has red(hot), black(hot), green(ground)
Here is a good example https://www.youtube.com/watch?v=DqefJ2MQrRo
Name:  Capture2.jpg
Views: 10181
Size:  23.8 KBName:  Capture3.jpg
Views: 9781
Size:  23.2 KBName:  Capture.jpg
Views: 9118
Size:  15.2 KB
I really hope that I don't have Case 4 in the house so that I can avoid many problems.

Based on your comments, if my new house's dryer has the outlet same as above pictures, then I cannot convert the 240v outlet directly to 110V. Frankly, I feel confused here and I don't understand why code doesn't allow this modification. As far as I know, I cannot imagine any unsafe issues here.

Thank you
 

Last edited by q0987; 05-08-15 at 08:58 PM.
  #12  
Old 05-08-15, 09:05 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Case 2> the 240V outlet has red(hot), black(hot), bare(ground)
No. You have no neutral but the cable you describe is only used in Canada.
Case 3> the 240V outlet has white(hot), black(hot), bare(ground)
Yes but it would not be an electric dryer circuit.
Case 4> the 240V outlet has red(hot), black(hot), green(ground)
No, but no cable has those colors. It would be conduit and you might be able to pull a white in.
Case 1> the 240V outlet has red(hot), black(hot), white(neutral), bare(ground)
Yes that will work.
 
  #13  
Old 05-08-15, 09:11 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,224
Received 105 Votes on 91 Posts
Just plug the dryer into the washer receptacle.
 
  #14  
Old 05-08-15, 09:19 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
In my post #6 I replied:
Question 2> Do dryer and washer require separated breaker or they share one?
Yes if you mean a gas dryer. Best practice it should be a dedicated 20 amp circuit. In some cases it may need to be GFCI protected.
But you don't seem to want to take the easy way. Why don't you want to use the washer receptacle?
 
  #15  
Old 05-08-15, 09:19 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Sorry for those silly questions I have posted.
I will upload more house circuit pictures after I have access to it.

From the video in YouTube, I realize the typical case is black(hot), white(hot), and bare(ground) or black(hot), white(hot), and green(ground).
I hope mine are these cases as this so that I can easily make the change.

But safety first, I will post more pictures for you and then get the final solution before I make any modifications.

Thank you again!
 
  #16  
Old 05-08-15, 09:22 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Did you see PCBoss' and mine preceding posts?
 
  #17  
Old 05-08-15, 09:27 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello pcboss,

If I remember correctly, both European dryer and washer have a very large power plug and I assume they are all 240V. The dryer is an electrical one so 240V is must.

Even if the washer uses 110V, I still am out of luck because the installer requires two wall outlets for both dryer and washer by code.

My best bet is to convert both 240V outlets into 110V without wiring a new outlet.

Thank you all.
 
  #18  
Old 05-08-15, 09:35 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello Ray,

If you have a three wire receptacle you have black, white ground. That can be converted to 120v. If it is a dryer or stove you would most likely have black, white, red no ground. That can not be changed to 120 because a none of the colors can be used as a ground.
I think this is the key argument I just missed. Based on my research, any 240V AC outlet must have a ground wire and ground wire should be either green or bare. The neutral wire for 240V AC outlet is optional and it can be white color.

Question> Now why the 240V dryer outlet uses the setting as "black, white, red no ground" in the first place?
Since we cannot use white for ground as you indicate early. Then what is the usage of white in the dryer outlet?

Thank you
 
  #19  
Old 05-08-15, 09:36 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
All residential washers in the U.S. are 120 volt (with very minor exceptions). How the heck did European washers get dragged into this.
 
  #20  
Old 05-08-15, 09:45 PM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello Ray,

Yes you are right, but the original owner has the setting and they will keep both machines after selling the house b/c they are high quality machines?!. So I have to make some changes in order to buy 110V electrical washer and gas dryer.

Thank you
 
  #21  
Old 05-08-15, 10:21 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Then just run a new 20 amp 120 (not 110) circuit.
 
  #22  
Old 05-09-15, 07:08 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,224
Received 105 Votes on 91 Posts
I think you are still confusing the difference between a 240 volt circuit and a 120/240 volt circuit.
 
  #23  
Old 05-09-15, 07:31 AM
Handyone's Avatar
Member
Join Date: Aug 2000
Location: U.S.
Posts: 5,450
Received 0 Votes on 0 Posts
Man, this is a lot of info on 240V circuits.

Q,
Your problem is very simple. All you need to do is remove the receptacle after you move in. Post a picture of the wires in the receptacle box.

If you have: Black, Red, White, and bare ground, you can convert it to 120.

If you have: Black, White, and bare ground, you can convert it to 120.
 
  #24  
Old 05-09-15, 07:48 AM
Q
Member
Thread Starter
Join Date: Dec 2014
Posts: 252
Received 0 Votes on 0 Posts
Hello all,

Thank you so much for the great helps!

I will post detail images back after we close the house and move in.

Many many thanks!
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: