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MsFixIt
Single or double pole?

Funny thing about small projects in my 66 year old house.....they never stay small very long. Anyway, in my dining room area, sandwiched between two peices of glued together paneling, I located an outlet. the outlet itself is a 220.... after further exporation into the wall, it seems like that powered an air conditioning unit that was once in the wall (found a framed up and covered up location near the outlet void of insulation) I traced the wire in the attic, and it went to straight down into my panel in the laundry room. So, my question is, does 220 require a double pole breaker, or can it potentially run off of a single pole? I am trying to determine the voltage becuase nothing regarding my electric was ever labeled, and I have only been moderatly sucessful in my personal attempts.

Fencepost
Re: Single or double pole?

220 absolutely requires a double-pole breaker, because the circuit will have two "hot" lines -- nominally, 120V from line to ground/neutral and 240V from line to line.

If the existing circuit was wired by someone other than a licensed electrician, there's no guarantee that it's wired properly. Don't assume that just because the outlet has "250V" stamped on it that's what's actually running to it; use a voltmeter to be sure.

All "hot" legs of a circuit require proper overcurrent protection.

MsFixIt
Re: Single or double pole?
Fencepost wrote:

220 absolutely requires a double-pole breaker, because the circuit will have two "hot" lines -- nominally, 120V from line to ground/neutral and 240V from line to line.

If the existing circuit was wired by someone other than a licensed electrician, there's no guarantee that it's wired properly. Don't assume that just because the outlet has "250V" stamped on it that's what's actually running to it; use a voltmeter to be sure.

All "hot" legs of a circuit require proper overcurrent protection.

I have an old voltmeter somewhere, along with a host of other tools in that same somewhere :) Most of my eletrician friends use a digital. So, where do I put the leads on the old one.... I sure would hate to light myself up figuring this out. But, I need to know becuase if it's only 110, I am going to re-route it and use if for a garbage disposal.

Re: Single or double pole?
MsFixIt wrote:

I have an old voltmeter somewhere, along with a host of other tools in that same somewhere :) Most of my eletrician friends use a digital. So, where do I put the leads on the old one.... I sure would hate to light myself up figuring this out. But, I need to know becuase if it's only 110, I am going to re-route it and use if for a garbage disposal.

Old style mechanical voltmeters are very unforgiving. Set the dials wrong and smoke comes out the back.

You would have to set the "mode" switch to AC volts and the "range" high enough to read at least 250 volts. Be sure the leads are still in good shape and plugged into the "com", which is usually black and the "volts" jack, which is usually red.

Read the instructions that came with the meter and turn off the breaker while attaching the leads with alligator clips. Don't attempt to work the circuit live.

Verify the meter is working by reading a known voltage first, such as the 120 volts at a common receptacle.

If any of the wires read from 210 to 250 volts it's called a 240 volt circuit and requires a 2 pole breaker and 2 pole disconnect, switch or 250 volt receptacle.

Most modern digital meters merely need to be set on the ac volts setting and will automatically adjust themselves to read correctly.

A. Spruce
Re: Single or double pole?
The Semi-Retired Electric wrote:

Old style mechanical voltmeters are very unforgiving. Set the dials wrong and smoke comes out the back.

Meters are calibrated at the factory with a specific amount of magic smoke, once you let that smoke out, there is no way to recalibrate the meter, you'll have to replace it. :p

On a more serious note, if you intend to split the 220 into a 110 line, you will need to replace the breaker with a 110 breaker, you can't just pull the keeper off the tip of the double 220 switches..

MsFixIt
Re: Single or double pole?

Thanks guys. I really do appreciate this. If it's 220, it's illegal and I need to fix it becuase it runs to a single pole on my subpanel in the laundry room.... Again, I think the contractor/persons who built this place was smoking something. I think the only reason it wasn't caught at inspection was becuase it was hidden. If it's just a 220 receptical wired to a 110 ciruct, no biggie other than to instal a GFI breaker and outlet (since I am going to move it witih 3' of a water source. Now... to tackle the newly discovered termite damage....just thanking the Big Guy upstairs that I have not come across an active infestation. *sigh*

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