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# converting 220 to 110

## converting 220 to 110

#1
03-04-04, 02:20 PM
dr.nick
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converting 220 to 110

I'm in the process of enclosing a patio to build-in a small office space. I've already wired all the fixtures and outlets and now just need to hook them up to power.

Since I only need 5 amps or so for the computer equipment and lites my plan was to punch through the wall and tap into the wiring in the garage. But come to find out the entire garage is on one 15 amp circiut and it powers a solar water heater pump as well as all the outlets and lites in the garage. So I've come to think that's a bad option.

I do have three 220 outlets in the garage. One is for the dryer but the other two are not in use and I'd like to canibalize one of them and convert it to 110 to power the office.

The outlet I want to convert to 110 is a twistlock 220. I took the outlet apart to look at the wiring and there are three 10ga. wires ... one black, one red, and one white. There is also a bare ground wire connected to the box but not the plug. The white and black are connected to the plug but the red is not ... it's just sitting there loose and it is stripped bare at the end. I'm assuming it popped loose from the plug when I pulled the outlet out because I can't imagine anyone would leave a hot(?) exposed like that.

Having never worked with 220 before I'm a little unsure of how to proceed. I assume the red and black are both hots (each one carrying 110) and the white is the neutral. Do I just carry the white through, pull the black for my hot and cap the red? Is there anything I need to do at the breaker box?

Could I also split the white and send it along with the red for another 30 amp circuit?

The breakers for the outlet are a clipped together pair of 30 amps.

Thanks,

- Nick

#2
03-04-04, 02:49 PM
dr.nick
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Follow up:

I put my meter on it ...

black/white = 125v

red/white = 125v

red/black = 250v

black/gnd = 125v

red/grd = 125v

- Nick

#3
03-04-04, 02:56 PM
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Yes, you can use this outlet if you want to.

However, you will need to replace the circuit breaker to be a 20 amp circuit breaker, and use 12 gauge wire from this location on.

You could use either the red wire or the black wire, in conjuction with the white and the bare ground wire to make a 120 volt circuit. You could use both the black and the red wires and make a multiwire circuit.

Your other option would be to use this wire to power a sub panel, from which you could run several circuits to your new room.

#4
03-04-04, 03:05 PM
Christopher
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You have the right idea

You are correct. But you do need to do something at the breaker panel.What size wire are you running from the outlet box to feed the office? If you are running 14 gauge wire then you need a spare 15amp breaker. So at the breaker panel if you do not have a spare 15amp breaker then you will need to remove the 2-pole 30amp breaker and install a single pole 15 amp breaker and get a panel blank cover for the unused slot in the panel.And put a wirenut on the end of the red wire in the panel.Make sure you have 120v between the black and white wires and check for same voltage between the black and ground wire also.You will need to hook up all your grounds in all boxes to all devices and switches. And if the boxes are metal bond all boxes also.You will definitly need a good ground for the computer.

#5
03-04-04, 05:47 PM
dr.nick
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I do actually have a box laying around that I could use as a subpanel. It looks fairy new. It was left over from a part of the house that was demo'ed in a remodel 2 years ago. It has one 15 amp breaker on one side ... one 15 amp and one 20 amp on the other.

It looks fairly simple to wire up but having never wired a box before let me talk through this and see if I'm making the correct assumptions.

... I'm assuming I take the black wire from my 220 outlet and connect that to one of the hex nuts at the head of the block of breakers. I connect the red wire from the 220 outlet to the other hex nut on the opposite side of the block of breakers. I wire the white from the 220 outlet to the connection block on the side of the subpanel box.

I wire the 14ga black from my 110v lighting wiring in the office to the output of one of the 15amp breakers. I wire the 12ga black from my 110v outlet wiring in the office to the output of the 20amp breaker. White from both 110v lighting & 110v outlets to the connection block. Connect all the ground wires to the grnd coming from the 220 plug.

Does that sound right?

Because I have two 30amp breakers on the main panel does that mean I have 30 amps total for my subpanel or 60 amps total (30amps on each side of the subpanel)?

Thanks so much for your help.

- Nick

#6
03-04-04, 06:08 PM
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Stop.

Subpanels are not that easy, and you would be wiring this one incorrectly.

Subpanels have very specific requirements about where they can be placed. I am not familiar with all of the requirements about where they can be placed, so I won't go there.

However, I do know this. In a subpanel, you must separate the neutral and the ground wire. They cannot be joined together. You must have a ground buss and a neutral buss. I believe that there also must be a main breaker for the sub panel.

I will tell you this. In your main panel you have a 220 breaker rated at 30 amps. You have 30 amps at 220 volts coming into the garage on this circuit. This means that at your sub panel you could supply 30 amps at 110 volts to each half of the panel.

#7
03-04-04, 06:42 PM
dr.nick
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Originally posted by racraft
In a subpanel, you must separate the neutral and the ground wire. They cannot be joined together.
Sorry for my ignorance, but it what way was I suggesting "joining them together"? By joined together do you mean the ground wire has to be run completely seperately from the neutral/hots from the sub to main?

Originally posted by racraft
You must have a ground buss and a neutral buss.
The neutral bus is self evident. But I don't see a ground bus. This box looks like it was previously wired with a separate 8ga(?) ground wire that leaves the box to be buried in the ground perhaps? The ground from outgoing wires are all connected together and also "grounded" to the box itself.

Originally posted by racraft
I believe that there also must be a main breaker for the sub panel.
This panel does not seem to have that option. Also a subpanel we have upstairs (that was part of the remodel I previously mentioned and done by a local electrician) does not have a main breaker. Does this mean that panel is out of code?

Originally posted by racraft
I will tell you this. In your main panel you have a 220 breaker rated at 30 amps. You have 30 amps at 220 volts coming into the garage on this circuit. This means that at your sub panel you could supply 30 amps at 110 volts to each half of the panel.
Thank you for clearing that up for me.

#8
03-05-04, 12:53 AM
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In a sub panel you do not connect the neutral and ground wires. They must remain separate.

The neutral wire from your main panel goes to one buss bar, while the graund wire from your main panel goes to a second buss bar. Keep the grounds and neutrals from your new wiring tied to their respective buss bars.

#9
03-05-04, 11:10 AM
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Dr. Nick,

In general, the neutral is supposed to be insulated electrically from the grounding system, in the same way that the hots are supposed to be separated.

The reason is that the equipment grounding conductors (the green or bare wires) and _not_ supposed to carry current in ordinary circumstances. The neutral wires (also known as the ground_ed_ conductors _are_ supposed to carry current; they carry the return current from the hot wires after the current has supplied the load.

If you were to connect the neutral wires and the grounding wires in more than one location, then the current would follow parallel paths in both wire systems.

The major exception to the rule for keeping neutral and ground separate is in the main service panel. At this one point the two conductor systems are 'bonded' together, for various technical reasons. This bond helps limit the voltage between the electrical system and ground to the desired design voltage, and provides a return current path should any 'hot' conductor come in contact with any grounded metal (eg your plumbing pipes).

Since most panels in homes are service panels, most of what us DIYers see are panels that have a _single_ bus that is used both for the ground and the neutral wires. When you install a 'sub-panel', you cannot combine the grounds and the neutrals on a single bus. This means that in your subpanel, you will need to buy an additional ground bus, and you will also have to make certain that the 'neutral' bus in the panel is _not_ bonded to the case. (Bonded electrically; of course it should be physically mounted )

As Bob said, there are _many_ details involved in planning a subpanel. You will likely need to do a bit of reading prior to installing one, and will have to ask more questions, but IMHO it sounds to me like a good use of the resources that you already have on hand (the 30A 240V circuit, the small panel, etc.)

-Jon

#10
03-05-04, 04:11 PM
dr.nick
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Thanks for all your input. I think I know enough to know "I don't know enough" to put this in myself. I think I'll just have to bite the bullet and pay an electrician to come out.

Thanks,

- Nick

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