How do I know if a have a neutral wire in my wall switch

Reply

  #1  
Old 08-20-13, 01:41 PM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
Question How do I know if a have a neutral wire in my wall switch

Hello.
First I want to thank for the help.
I want to buy a WeMo Wall Light Switch from Belkin (WeMo Light Switch | WeMo Home Automation | Connected Home | Products | Belkin USA Site) but as part of the requirements they mention: Neutral Wire Required.
I opened the wall switch at my home and I saw 3 cables: two red wires (one enters the switch and the other one exits the switch to the lamp) and one yellow wire.
I used a tester and that wire (yelloew) does not have electricity, but when I placed the tester one side on the hot red wire and the other side in the yellow wire, the tester marked 73V.
My question is: There is any safety way to understand if that yellow wire is a Neutral wire so I will be able to install the WeMo switch?
I dont want to buy the WeMo and not be able to install it.
Any help its appreciated.
If there is any additional info I can provide please let me know
Daniele.
 
Sponsored Links
  #2  
Old 08-20-13, 02:10 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,504
Welcome to the forums from Venezuela.

Your power is is similar to ours.....120v 60hz.

Test from the red wires to ground or the box.
Test from the yellow wire to ground or the box.

What did you measure ?
 
  #3  
Old 08-20-13, 02:45 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Those aren't cables, they're wires.

There is any safety way to understand if that yellow wire is a Neutral wire so I will be able to install the WeMo switch?
Turn the power off and disconnect the two red wires from the switch. Separate all three wires so that they cannot contact each other or the box.

Turn the power on and test from each red wire to the yellow wire and to the box. You should see 120V between one of the red wires and the box - if it's grounded - and between that red wire and the yellow wire, if the yellow wire is a neutral. You should also see 0V between the yellow wire and the box if the wire is a neutral and the box is grounded.
 
  #4  
Old 08-20-13, 07:46 PM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
Hello.
I did the following:
Measured from red wire 1 to the box and got 120V
Measured from red wire 2 to the box and got 0V (I assume that is the one that closes the circuit for the light)
Measured from the yellow wire to the box and got 22V (not 0V)
I hope this information helps understand the room wiring.
Please let me know if you need any additional information or test
Thank you for the help.

Ps. In Venezuela we speak spanish (not english) and we call cables the wires thats why I made the mistake naming it.
 
  #5  
Old 08-20-13, 08:13 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,504
You measured what we expected to see on the red wires.

However, it would appear that you have some type of neutral issue there unless that yellow wire is not a neutral.

Try checking between the slots on a receptacle to ground and see what the neutral measures as there.
 
  #6  
Old 08-21-13, 11:34 AM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
Hi PJmax.

Thank you for your help.

Could you please explain me what means "slots on a receptacle"?

I dont unsdertand what test you want me to try.

Thank you again,
 
  #7  
Old 08-21-13, 11:51 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,363
A receptacle is where you plug an appliance in. The slots are where the blades make contact inside the device.
 
  #8  
Old 08-21-13, 12:08 PM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
ok.. let me see if I understood... you want me test a wall outlet (one side at a time to ground) in the room to see the measure?
Its that correct?
Sorry if not but I dont want to make it wrong way.
Thank you
 
  #9  
Old 08-21-13, 04:50 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
In Venezuela we speak spanish (not english) and we call cables the wires thats why I made the mistake naming it.
Point taken. Two questions:
  1. Is it possible that the wire you're calling a yellow wire - un cable amarillo - could actually be an older, discolored white wire - un cable blanco?
  2. What are you using to measure the voltage? If you're using a digital multimeter, the 22 volts you saw from the yellow wire to ground could be induced voltage on the wire, not from the source. Analog multimeters are better at filtering out or not registering induced voltage.
you want me test a wall outlet (one side at a time to ground) in the room to see the measure?
I don't think that's what PJ was asking for but I like your suggestion. Also just measure from slot to slot on the receptacle (the "wall outlet").
 
  #10  
Old 08-22-13, 06:40 AM
Member
Join Date: Mar 2010
Location: USA
Posts: 2,860
What is the yellow wire connected to?

Using short wires with alligator clips on each end, connect up an incandescent light fixture with at least a 100 watt bulb. Connect it to the yellow wire and a red wire while the switch is still connected up. If you find that the makeshift light stays on bright and steady while you flip the switch and turn on and off the light the switch controls then you can make an educated guess that the yellow wire is a neutral.

The colors used in Venezuela may be different from those used in the U.S. and Canada. In the U.S. any color except white, gray, and green is for a hot wire.

Also, techniques may differ. In the past, there was wiring in the U.S. where only the neutral entered the switch box and was switched. That is no longer permitted in the U.S. (or Canada); the switch must interrupt the hot wire.
 
  #11  
Old 08-22-13, 03:25 PM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
Hello Nashkat1. Thank you for your help.

Here the answers:
1.- Yes, it can be an older wire but not a discolored wire. Maybe at some point in time the older owner of the apartment rewire the room and added new wires and disconnected the old ones.
2.- I'm using a digital multimeter. I will need to find one analog. I'll let you know as soon as I find it a redo the test.

Thank you for your help.
 
  #12  
Old 08-22-13, 03:31 PM
Member
Thread Starter
Join Date: Aug 2013
Location: Venezuela
Posts: 6
Hello AllanJ

I have no idea to what is connected the yellow wire.

I will have to bring down the ceiling lamp (its hard, that why I havent done that yet) to see if the yellow wire is connected to something.

Question: The connection you are suggesting is at the ceiling end or at the switch? Sorry but I'm not sure I understood correctly to which red wire you want me to connect.

I will connect one end to the yellow wire and the other end to one of the two red wires (the one that enters the switch or the one that exists the switch?) and see what happens to the light. It's that correct?

Thank you for the help.

Daniele.
 
  #13  
Old 08-25-13, 11:40 AM
Member
Join Date: Mar 2010
Location: USA
Posts: 2,860
About the yellow wire, what I meant was, in the switch box you have open, what is/was the yellow wire end you are touching attached to.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'