Electrical question: how to check if the home has 220v coming in

Thread Starter

yourminky

Joined May 31, 2019
33
I know this forum is for circuits. However, I have a electrical related question. Most new homes have two 110 volt lines coming in and the phase difference between the two lines is 220v. All of my electrical equipment including air-conditioner and dryer are 110v.
I know I can take the main circuit breaker cover off and check the voltage with a voltmeter. However, I am looking for an option that does not require me to open the circuit breaker box.
How to check if my home already has 220v coming in without opening the circuit breaker box?
All of my wiring is underground. No over-head supply lines. Even the step-down transformers are in secured and locked distribution boxes throughout the neighborhood.
 
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BR-549

Joined Sep 22, 2013
4,928
Do you have any equipment that uses 220V? A furnace or heat pump? AC? Hot water heater? Kitchen stove or oven? Clothes dryer? Well pump?
 

crutschow

Joined Mar 14, 2008
34,285
If it has 220V, there will be three wires from the power line to your electrical panel, two hot and one neutral.
Measuring across the two hot leads, should give you 220V.
 

Thread Starter

yourminky

Joined May 31, 2019
33
If it has 220V, there will be three wires from the power line to your electrical panel, two hot and one neutral.
Measuring across the two hot leads, should give you 220V.
I have seen both 4-wire and 3-wire setup for 220 volts. Some have 2 live, 1 neutral and 1 ground. Some 220 volt setup do not use a neutral, they have 2 live and 1 ground.
All of my wall panels are 110 volt. I still may have 2-phase 110 volt coming in my house. How to tell the house has 1-phase or 2-phase service without opening the circuit breaker?
 
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BR-549

Joined Sep 22, 2013
4,928
It's single, split phase. There should be three wires entering your house in NA. 220V with a split phase neutral. The neutral is connected at ground in your power panel. Your house has it's own ground rod........to reference that ground.
 

Thread Starter

yourminky

Joined May 31, 2019
33
It's single, split phase. There should be three wires entering your house in NA. 220V with a split phase neutral. The neutral is connected at ground in your power panel. Your house has it's own ground rod........to reference that ground.
Thanks for your comment but as I mentioned I cannot see any wires entering my house. Everything is underground and coming through steel protective rods.
 

BR-549

Joined Sep 22, 2013
4,928
Ok.....I can't read minds. Can you get to your power panel? Can you take a snapshot of it? Is there any information on the panel?
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I guessed you were in N.A. from the way described your split phase power, the most common is N.A. many others are a 1ph and neutral, derived from 3ph, BTW, for some time now, N.A. has been 120v-240v, although you will still often see appliances marked with the old 110v rating.
As already mentioned, if you have a large stove/range or a clothes dryer etc, you will be able to easily check if you have 120v-240v service.
Max.
 
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MaxHeadRoom

Joined Jul 18, 2013
28,619
I believe all 220V outlets have a different type of socket, you cant connect 110V to a 220V socket. Google '220V outlet socket'
For simple 240v appliances from 15a to 30amp the plug/socket power pins are horizontal, instead of vertical as in the 120v version.
Max.
 

SLK001

Joined Nov 29, 2011
1,549
Most new homes have two 110 volt lines coming in and the phase difference between the two lines is 220v.
Phase is measured in degrees, not volts. You have two 110v lines with the phase difference of 180°.

All of my electrical equipment including air-conditioner and dryer are 110v.
I doubt that... How did you determine this?

How to check if my home already has 220v coming in without opening the circuit breaker box?
Here's a quick way... Go to GOOGLE EARTH and find your location therein. If your location is in NORTH AMERICA, then your input voltage is 220V. Easy peasy.
 

ElectricSpidey

Joined Dec 2, 2017
2,758
Get a long extension cord, plug it in and move to various other outlets in your property, measure from hot to hot using a multimeter, and unless all of your outlets are wired to the same phase, you should see 220 at some of them.
 
i was writing this as @ElectricSpidey posted. It's much more detailed.

A pic of the breaker panel might help.

Are there any breakers that are tied together?

The main breaker should be tied together mechanically.

==

What will make it difficult is if the circuits have "tamper proof" receptacles. You can't push in one side to get a reading. You need to be able to measure 120 VAC at an outlet. That, in itself, can sometimes be difficult. Use another short polarized extension cord if that's the case.

In a typical panel with breakers arranged vertically, the breakers will alternate phase so when you insert a 240 V breaker, it takes up two ajacent spaces.

That said, locate two breakers next to one another vertically.

Turn off one of the breakers and locate an outlet that turned off. (Circuit #1)

Do the same with the other one. Locate an outlet that turned off. (Circuit #2)

Now turn both breakers on and connect an outlet from Circuit #1 to to a long extension cord and take the female part to where circuit #2 is located.

Now measure between the female socket (short receptacle) of the extension cord (Circuit #1) and the female socket (short side) of Circuit #2.
You should have 240 V. Nearly zero would mean unconnected, you made a mistake, or you have only 120.

==

Things that are likely 240 VAC are an electric stove, an outdoor AC unit, electric heat and an electric water heater.
 
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Will people at least read the TS post? He does not have a way to measure... 'no voltmeter'
We did. You apparently didn't. His requirement is to not open the main box.

I know I can take the main circuit breaker cover off and check the voltage with a voltmeter. However, I am looking for an option that does not require me to open the circuit breaker box.
 
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