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Old 12-31-2009, 08:15 PM   #1
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240 to 120


Hi I just wanted to know how I can go from 240 to 120 volts? I have this wire inside my kitchen island and it has 4 wires red, white, black, bare or copper so I tested it and it showed 120 but when I installed it it shows 240. Now I can't remember if I tested the white with black which must of been 120 and I installed red and black that is 240 could that be pretty much what I did and if I just connect the white and take off the red will that give me 120? Also do I have to downgrade the breaker to a lower amp or can I just leave it?

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Old 12-31-2009, 08:46 PM   #2
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240 to 120


What size is the wire & what size is the breaker ?
Do you know what was installed that this line fed ?

With 10-3 or 12-3 you can connect black, white & green/bare & get 120v
This is PROVIDED that it is connected correctly at the breaker panel
AND that it is a 20a breaker
It's also possible this is part of a MWBC (multi-wire branch circuit) & that you could have (2) 120v circuits

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Old 12-31-2009, 11:57 PM   #3
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240 to 120


Here's a description of how 3 wire / 4 wire 240 volt circuits work and are wired. http://www.nojolt.com/Understanding_...circuits.shtml
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Old 01-01-2010, 03:36 AM   #4
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240 to 120


Quote:
Originally Posted by Scuba_Dave View Post
What size is the wire & what size is the breaker ?
Do you know what was installed that this line fed ?

With 10-3 or 12-3 you can connect black, white & green & get 120v
This is PROVIDED that it is connected correctly at the breaker panel
AND that it is a 20a breaker
It's also possible this is part of a MWBC (multi-wire branch circuit) & that you could have (2) 120v circuits
I'm not sure on the gauge it is solid copper could be 14 AWG and there was nothing installed on that line before it was just lying there. and as for the breaker the sticker that tells me what amp it is is torn off but it take twice the room as a reg 10 amp breakers. I was going to connect the white and take off the red to see what it does but i'm just wondering if I have to downgrade the breaker?
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Old 01-01-2010, 07:02 AM   #5
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240 to 120


THE first thing you have to do is follow Scuba Dave , What size is the breaker or breakers ? Even if the tag fell off it should still be engraved somewhere on the breaker as to the size IE: 15, 20, 30.

You also have to find out the wire size somehow then post back.

And when you say you installed the wire what do you mean by installed?

If you can provide that information I am sure plenty of people can help you.
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Old 01-01-2010, 07:40 AM   #6
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240 to 120


Correct voltage reading:

Red-Black -- 240 volts
Red-white -- 120 volts
Black-white -- 120 volts
Red-Ground -- 120 volts
Black-ground -- 120 bolts
White-ground -- 0 volts

(Voltages are approximate)

Your 120 volts loads (lights, receptacles) should be divided about evenly between red-white and black-white.

If all wires on all circuits and subcircuits attached to the breaker are 12 gauge or fatter, you may use a 20 amp breaker pair. If any are 14 gauge, then use a 15 amp breaker pair. The breaker must be double wide with handles tied together with the red and black connected to the two hot screws respectively.
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Last edited by AllanJ; 01-01-2010 at 07:46 AM.
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Old 01-01-2010, 07:49 AM   #7
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240 to 120


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Originally Posted by sammy004 View Post
as for the breaker the sticker that tells me what amp it is is torn off but it take twice the room as a reg 10 amp breakers. I was going to connect the white and take off the red to see what it does but i'm just wondering if I have to downgrade the breaker?
The white wire is neutral. Do not connect the white wire of this circuit to the breaker except to the neutral screw of a GFCI or arc fault breaker.
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Old 01-01-2010, 07:00 PM   #8
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240 to 120


Ok I got it it is a 14 gauge wire and the breakers are 2 10 amp breakers tied in with a center piece so if I turn one off the other is turned off as well. So does that make that into a 20 amp breaker? I took off the black wire and replaced it with the white one and then the copper one is still there so I got 120volts but when I check it with my test light it is telling me reverse polarity should I turn the white and red around or can I just leave it for a while because I really don't want to open it up again, I'm tired ?
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Old 01-01-2010, 08:03 PM   #9
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240 to 120


Are you sure they are 10a breakers & not 15a ?

No the breakers do not add for power available

Red = hot to one breaker
Black = hot to the other breaker
White = neutral
Bare/copper = ground

1 Outlet = use black on hot , white on neutral, ground NO red
2nd outlet = use red on hot , white on neutral, ground NO Black

If you only have one outlet (receptacle) you can make it a split receptacle
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Old 01-01-2010, 08:41 PM   #10
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240 to 120


Quote:
Originally Posted by Scuba_Dave View Post
Are you sure they are 10a breakers & not 15a ?

Ne
if I remember some of what I have read, I believe Canada uses some 10 amp breakers.



sammy, are you in Canada (not that it changes the voltage connections, just would explain that 10 amp thing, maybe)
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Old 01-01-2010, 09:00 PM   #11
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240 to 120


Yes - his IP does track to Canada
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Old 01-01-2010, 09:33 PM   #12
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240 to 120


yes I am from Canada and the breakers do say 10 amp on them. I only want one receptacle but what is a split receptacle?
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Old 01-01-2010, 09:41 PM   #13
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240 to 120


that is where each receptacle of a duplex is fed by a different circuit. If I remember what I hear on the forum, you are required to install split receps in the kitchen in Canada. Don't rely on that to make your installation but I thought I read that.

there are little tabs connecting the two recep sections together

you can see it on this recep. It is even tagged for you

http://gilchrist-electric.com/Images...ptacle_tab.jpg

ignore the "switched". If you break that tab off, it will isolate one recep from the other so you can attach 1 circuit to each of the receps. You would leave the tab intact on the neutral side as you are using a multiwire branch circuit with a shared neutral.

Last edited by nap; 01-01-2010 at 09:44 PM.
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Old 01-02-2010, 07:19 AM   #14
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240 to 120


You will get 20 amps @ 120 volts via the red/white/black (3 conductors plus ground) cable and the double 10 amp breaker only when half of the loads, max 10 amps (lights, appliances) are on the red/white pair and the other half, max 10 amps, are on the black/white pair. Of course some of the time lesser amounts may be consumed for example 7 amps on the red/white pair and 4 amps on the black/white pair.

You might also have 240 volt appliances using the red/black pair. Here the 240 volt stuff and the red/white 120 volt stuff together have a maximum of 10 amps and the 240 volt stuff and the black/white 120 volt stuff together have a maximum of 10 amps (10 amp breaker pair).

Using modern receptacles sold in the U.S. the white wire is connected to the side with the slightly larger prong hole and/or silver screw, and the red or black wire is connected to the side with the slightly smaller prong hole and/or gold screw.

When the same red/black/single-white cable line is to be daisy chained to additional receptacles or lights, the white wire coming in and the white wire continuing on must be connected to each other directly (using a wire nut) and a short segment (pigtail) used to reach the receptacle screw. For this purpose do not break the jumper between the two silver screws otherwise you will need two pigtails.
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Last edited by AllanJ; 01-02-2010 at 07:28 AM.
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Old 01-04-2010, 02:43 PM   #15
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240 to 120


OK guys I got it all hooked up it is reading 120V on the meter but it is saying reverse polarity with a test light is that OK can I leave it like that?

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