Confused about 220v

[jam022316]

Hey all. Hoping someone can explain 220 to me and if I'm able to wire for it.
Currently I have 200 amp service in my home. I have two 50 amp breakers in that box that are the main power for my garage (two power lines, 50 amps a piece).

Am I able to wire up a 220v circuit in my garage, and if so, how do I go about doing that?

Here's some pics as you guys requested

Garage panel:

Main box in house

Breakers that run power to garage

 

[larry_g]

I hate questions like this... This is not something to try and learn on the internet as there are a lot of variables to doing this. Do you already have a panel in the garage? What is it, can you post a picture. It should be no big problem but may be a big job, just depends on what you have. My advise would be to try and get someone qualified onsite that can lay out the process for you and then come back and confirm you have done it correctly.

lg
no neat sig line

 

[Steevo]

Take a picture of the double breaker in your main panel that is feeding your garage.
Then take a picture of the panel in the garage, preferably with the cover removed so the breakers and wiring are visible.
Post them here along with your question, and you should be able to get some useful responses.

 

[Stuart in MN]

I have two 50 amp breakers in that box that are the main power for my garage (two power lines, 50 amps a piece).

Do you have two individual (single pole) 50 amp breakers, or one 50 amp two pole breaker? Are they (or it) supplying power to a subpanel in the garage?

Below is a simple diagram I found online that shows the basic relationship between 120 and 240 (not 220) volts. The squiggly things on the left side represent the power company's transformer outside your house. In laymen's terms what you're getting from the power company is 120/240 volts. There are two hot wires and a single neutral wire coming into the main panel, and from hot to hot you have 240 volts and from either hot to the neutral you have 120 volts. The individual slots in the panel are fed alternately from the two hot wires.

A 120 volt circuit requires a single pole circuit breaker, one hot wire. A 240 volt circuit requires a two pole circuit breaker, two hots. A two pole circuit breaker kind of looks like two single pole circuit breakers side by side, but the little handle on it opens and closes both legs of the circuit simultaneously - you can't just use two single pole circuit breakers.

 

[jam022316]

Thanks for all the responses so far. I will take some pics when I get home. I believe I have two single pole 50 amp breakers feeding my subpanel in the garage. One for each leg of the box. I will verify when I get home and get back to you all.

 

[ddawg16]

As Stuart said....it's 240Vac, not 220....

Basically, you have 2 120Vac lines going to your house with a single common (white) wire.

Those 2 120Vac lines are 180 deg out of phase. Measure from either one to common and you get 120Vac. But measure from one 120Vac line to the other 120Vac line and you get 240Vac.

If you look inside the typical load center (CB Box), you will see 2 rails going down the center of it. Each rail is 120Vac. You will also notice that they are not straight rails...the zig and zag.

When you plug in a circuit breaker, it is connected to one of those rails. When you plug in a CB next to it....you will notice that it connects to the other rail (remember the zig zag?). Hence, any double breaker is going to be 240Vac because each breaker catches one of the 120Vac rails.

Clear so far?

So, on that power to your garage....you will have 4 wires.....2 120Vac's, one white (neutral) and a ground.

In your garage I'm going to assume that it is a sub-panel for 240Vac. If so, it will have the zig zag rails as well. That will allow you to have both 120Vac and 240Vac.

Does that clear it up?

 

[jam022316]

I think it does (I'll still get pictures so I don't mess anything up). Sounds like I need to get a double pole breaker and the outlet would have two hot connections and one for neutral and ground, correct? So how do I determine how big of a breaker to use and what size wiring.

Sorry for all the questions. Just want to make sure I don't risk my family's lives because I want a bigger compressor

 

[Interex]

Sounds like I need to get a double pole breaker and the outlet would have two hot connections and one for neutral and ground, correct?

Correct.

So how do I determine how big of a breaker to use and what size wiring.

That will depend on your load. You mentioned this is for a compressor, correct? You will need to look at your compressor motor specifications to see how many amps it draws. Take that number, add 20%, and you've got your answer on what size breaker you will need. The size of wire will depend on how much wire you'll be using to get from the breaker box to the compressor.

 

[lametec]

As Stuart said....it's 240Vac, not 220....

<snipped>

Those 2 120Vac lines are 180 deg out of phase.

Well, if one is to nitpick, the two 120V lines are not 180° out of phase. They are inverted with reference to each other, in phase.

As long as we're talking a pure sine wave, inverted and 180° out of phase looks the same on a scope, but if we inject some noise onto half of those sine waves (say the first 180°), inverted now becomes very different from 180°.

For the 120V lines to be 180° out of phase means that one 120V line will start "moving" 1/2 cycle after the other. This is of course not how it is. The moment power is applied, one 120V line increases in voltage, while the other decreases in voltage at the very same time by the very same amount.

Since the to 120V lines come from a single 240V line, just split in half, the two have to in phase, as long as delay isn't inserted into one line.

So in other words, if there's a voltage spike of 10V on the 240V for half a cycle, both 120V see the same 10V spike (but divided equally among them) at the same time, so they are in phase.

But I digress.

 

[ddawg16]

Ok.....now your going to have the OP really confused.......just don't mention RMS.

 

[Thruxton]

Go to your favorite big box store and get a DIY wiring book. Study and come back. Coming to this forum is a very bad way to go about learning how to wire up even simple circuits, but a very good way to get explanations of things you don't understand after you know some of the basics.

 

[ddawg16]

Go to your favorite big box store and get a DIY wiring book. Study and come back. Coming to this forum is a very bad way to go about learning how to wire up even simple circuits, but a very good way to get explanations of things you don't understand after you know some of the basics.

Haven't you heard? Some have been recalled due to incorrect information.

 

[dittle fart around]

There's a reason Electricians go to trade school to learn about electricity. Yea you could probably do it yourself and not die. But is taking that chance really worth the money you would save?

 

[jam022316]

Ok.....now your going to have the OP really confused.......just don't mention RMS.

I agree. That went straight over my head and almost tmi!

There's a reason Electricians go to trade school to learn about electricity. Yea you could probably do it yourself and not die. But is taking that chance really worth the money you would save?

I'm very capable of doing this myself. I respect it and know it can kill me which I think is important. Where's the fun in hiring someone to do it for a lot of money when I can do it myself, learn something and be proud of it?


Back to the topic, I have one spot left on the left and 3 spots left on the right in the panel in the garage. Many questions I have, and I'm probably making it harder than it needs to be.

1. I need to get a double pole single throw switch for the main box to replace the two single pole breakers powering the garage. My question, why is that? What is wrong with the setup I have now?

2. How much is technically going to my sub panel? Is it 240volts at 100 amps? 110volts at 100 amps? 110volts at 50amps

3. Is it safe to go ahead and wire in a 240v outlet to my subpanel?

4. I don't have a compressor in mind yet, just want to get something good. What would be a good wire/breaker combination to cover most compressors?

 

[Aceman]

First things first.

Attached or detached garage?
Where is the ground wire feeding the garage panel?

 

[jam022316]

First things first.

Attached or detached garage?
Where is the ground wire feeding the garage panel?

Attached garage. You can't really tell from the picture but the very top wire on the ground bar is the ground of the wire coming into the box. The power cable had a red,black,and white, that were all 6 guage (I believe it's six, can't remember) and in that it also had a ground wire which is connected to the ground of the main panel.

 

[Charles (in GA)]

From the pic of the sub panel in the garage, and the fact that it has 4 wire supplying it, and that you have two adjacent open breaker slots, this is about as easy as it gets.

Plug in a double pole breaker of the appropriate brand and amps, and run two hots, a ground and if needed, a neutral. I've taken to carrying a neutral to the receptacle, even if it is not needed, might come in handy later, but if you are wiring a 240v air compressor or such, you don't need a neutral, just two hots off the breaker and a ground.

You have 50 amps supplying your subpanel. With a double pole breaker, imaging one side is current out, one side is current back at 240v (its not quite that way, but easy to understand). With 120V, you have one side out (the breaker) and one side back (the neutral). One side of the double pole breaker serves the same purpose as a neutral on 120v, but since its on a un-grounded bus bar, it has to be protected by a breaker, hence the double pole.

If they still make that panel, you may be able to get a handle tie to connect the two 50 amp breaker handles together. If not, you need to locate a double pole breaker to replace it, which is nothing more than what you have now, with a handle tie. You want both sides to trip together, its a safety thing, if one trips and one remains hot, you can have safety issues. Code requires common trip on a feeder such as this. If the existing breaker handles have holes thru them, it is for installing a handle tie, you just need to find one to fit it.

Since its attached, you do not need any sort of main disconnect at the sub panel. The 50 amps (when the handles are tied together) serve this purpose.

Charles

 

[jam022316]

From the pic of the sub panel in the garage, and the fact that it has 4 wire supplying it, and that you have two adjacent open breaker slots, this is about as easy as it gets.

Plug in a double pole breaker of the appropriate brand and amps, and run two hots, a ground and if needed, a neutral. I've taken to carrying a neutral to the receptacle, even if it is not needed, might come in handy later, but if you are wiring a 240v air compressor or such, you don't need a neutral, just two hots off the breaker and a ground.

You have 50 amps supplying your subpanel. With a double pole breaker, imaging one side is current out, one side is current back at 240v (its not quite that way, but easy to understand). With 120V, you have one side out (the breaker) and one side back (the neutral). One side of the double pole breaker serves the same purpose as a neutral on 120v, but since its on a un-grounded bus bar, it has to be protected by a breaker, hence the double pole.

If they still make that panel, you may be able to get a handle tie to connect the two 50 amp breaker handles together. If not, you need to locate a double pole breaker to replace it, which is nothing more than what you have now, with a handle tie. You want both sides to trip together, its a safety thing, if one trips and one remains hot, you can have safety issues. Code requires common trip on a feeder such as this. If the existing breaker handles have holes thru them, it is for installing a handle tie, you just need to find one to fit it.

Since its attached, you do not need any sort of main disconnect at the sub panel. The 50 amps (when the handles are tied together) serve this purpose.

Charles

Thanks for the great info! Any advice on common breaker size and wiring that would cover the demand of most compressors?

 

[brewchief]

Back to the topic, I have one spot left on the left and 3 spots left on the right in the panel in the garage. Many questions I have, and I'm probably making it harder than it needs to be.

Looks to me like only 2 open spaces on the right, sometimes the panel cover will have more slots then are actually in the panel.

Also looks like no wire protectors on the wires entering from the left side, I would try to get some type of wire protector in there if at all possible.

 

[BigJohn20]

Also looks like no wire protectors on the wires entering from the left side, I would try to get some type of wire protector in there if at all possible.

And this is why I love the Arlington NM94 NM-B connectors. Takes all of 5 seconds to fix when the last guy punched a KO and didn't use a connector.

 

[jam022316]

Looks to me like only 2 open spaces on the right, sometimes the panel cover will have more slots then are actually in the panel.

Also looks like no wire protectors on the wires entering from the left side, I would try to get some type of wire protector in there if at all possible.

I'll have to double check, you could be right. As far as the wires on the left, would a rubber gromet work?

 

[jam022316]

Also, I've been wanting to replace the main panel with for reliable breakers (I was told these breakers were taken off the market due to not fully shutting off and arching). How dangerous is it to pull the meter? Would the electric company pull the meter and put it back no questions asked? I'm not going to pay an electrician $1000 to swap out the panel.

 

[BigJohn20]

Also, I've been wanting to replace the main panel with for reliable breakers (I was told these breakers were taken off the market due to not fully shutting off and arching). How dangerous is it to pull the meter? Would the electric company pull the meter and put it back no questions asked? I'm not going to pay an electrician $1000 to swap out the panel.

Potentially extremely dangerous. There's a reason why the rules call for a full kit of PPE gear when pulling the meter. There's a potential for an arc-flash that could permanently injure or kill you.

The utility may or may not require any work done to be inspected before they replace the meter.