110v vs 220v for pool pump.

TomAtlanta

Well-known member
Sep 10, 2011
334
Atlanta Ga
I know a pump will burn out faster on 110, but how much faster? I am trying to decide if it is worth the money to get an electrician to fix the 220v going to my pool pump area. This is for a 1hp motor.
 

cfherrman

TFP Guide
May 10, 2017
2,280
Hays, Kansas
Everything being the same, everything is the same, so make everything the same.

Or if you want to understand that, 110v is only a problem when you cheap out
 

Jimrahbe

Mod Squad
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Jul 7, 2014
13,628
Bedford, TX
Tom,

I am not sure what you say is true.. But the cheaper the pump, the shorter their life span.. And my guess is that the average pool owner with a 120 volt pump will try to replace it with the cheapest pump they can find..

Are you saying a pump that is designed to run on 120 or 240, will burn out faster when run on 120 volts?? If so, I have never heard that before.. :scratch:

Thanks,

Jim R.
 

TomAtlanta

Well-known member
Sep 10, 2011
334
Atlanta Ga
Are you saying a pump that is designed to run on 120 or 240, will burn out faster when run on 120 volts?? If so, I have never heard that before..
I read that somewhere on this forum. I don't understand enough about electricity and motors to explain it very well, but someone said the pumps ran hotter at 120. I will try to find a link to that discussion.
 

cfherrman

TFP Guide
May 10, 2017
2,280
Hays, Kansas
At 120 they pull 2x more amps, that is the only difference. The real difference is you can put a junk extension cord on a 110v pump causing it to pull more amps and run hotter, at 220v it's hardwired with the proper sized wire at the footage.

Everything being the same everything is the same
 

mas985

TFP Expert
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May 3, 2007
12,628
Pleasanton, CA
I read that somewhere on this forum. I don't understand enough about electricity and motors to explain it very well, but someone said the pumps ran hotter at 120. I will try to find a link to that discussion.
If the mains supply wire is sized appropriately, the current going through the winding's is exactly the same wired for 240v vs 120v. However, if the wire or cord is undersized, this can lead to a larger voltage drop for the 120v case than for the 240v which can lead to a higher current draw for 120v (and higher motor temperature).
 

TomAtlanta

Well-known member
Sep 10, 2011
334
Atlanta Ga
Thanks for the info everyone.

So why do they make the pumps work on both 120v and 240v ? Why ever use 240v if there is no advantage?
 

mas985

TFP Expert
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May 3, 2007
12,628
Pleasanton, CA
There is an advantage in wire size. 120v requires a lower guage wire and thus a larger conduit. So 220v installation should cost slight less although 220v requires dual breakers so that negates some of the advantage.

But in reality the choice is usually more about what is available.
 

Steve_in_C

Bronze Supporter
Jul 6, 2017
333
Kinston, NC
In common language, people often refer to 110V/220V. Single phase US voltage is actually 120V/240V. One of the previous posters pointed out that the higher voltage uses half the amps. There is also less voltage drop using the higher voltage. That's why you can get by with smaller wire. Any type of switch, timeclock, contactor, relay, or even the starter circuit in your single phase pool motor has "contact points" that open and close. These "points" carry the load and will last longer with lower amps. Now these differences may be negligible with your 1HP motor but with larger motors and bigger draws, they become more significant. That's why most larger motors are wired at higher voltage than 120V. So if you are having some wiring done or putting in new, consider 240V. If what you have is working adequately, there likely isn't enough advantage to be worth the cost.

There is one more thing to consider. If your pump failed due to a motor issue, it could be caused by excessive voltage drop. The general rule of thumb is no more than 5% voltage drop (under a load). So if you know someone with a voltmeter you could ask them to measure the voltage at the pump when it is running. If the voltage is any lower than 120V - 5% or 114V, then you could have more heat production, less efficiency, and premature failure of your pump motor.
 

CJadamec

TFP Expert
Apr 29, 2016
2,390
Quaker Hill, CT
I've always designed my circuits for no more than 3% voltage drop. A 5% drop increases the risk of voltage related electronics issues quite a bit. If you want to get technical about it though the NEC code allows for different voltage drops based on how each circuit will be used and where it is used.

Residential voltage can be either 110/220 or 120/240 or 108/210. It really depends on the local power grid and how and where the transformers feeding your house are tapped and located. These voltages are also nominal voltages. What is actually making it to the power panel in your home needs to be verified. If your panel is starting out with a lower than average voltage allowing for an additional 5% drop before it gets to the end device can really cause issues.

At the end of the day there is no real tangible difference in motor design or life span for a 110v or a 220v motor. As long as the motor is fed by a properly designed circuit that can handle the current draw of the motor.

The reason 110v motors seem to fail more often is simply that there are more of them and they are often plugged into any plug you can find without any consideration for weather or not the wiring to that plug can handle the motor. 220v motors seem more durable because there are far fewer of them in a home and they are almost always installed on circuits specifically designed for the needs of the motor.
 

Richard320

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Jan 6, 2010
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San Dimas, CA (LA County)
All things being equal, is a 220v 1hp Pump using less watts than a 110v Pump? I was always told it was half.
Nope. Exactly the same. Amps X Volts = watts. Look at the plate on a dual-voltage motor. It'll show two amperages-- one is half the other. It'll also show two voltages -- one is twice the other. It cancels.
 

Jimrahbe

Mod Squad
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Jul 7, 2014
13,628
Bedford, TX
Half the amps

220v at 3.5 amps

110 v at 7 amps

Note hp = watts, you could say a 750 watt pump and it means the same as a 1 hp pump
Casey,

Sorry, but it is not half the amps, because each leg of the 220 pulls 3.5 amps each for a total of 7 amps..

Jim R.
 

cfherrman

TFP Guide
May 10, 2017
2,280
Hays, Kansas
220 x 7 amps is double the watts of 110 x 7 amps

If you measure each leg of 110, I believe it's been awhile, each leg will pull 7 as well
 

JamesW

TFP Expert
Mar 2, 2011
15,592
A pump running on 230 volts will be pulling half the amps of a pump running on 115 volts.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,628
Pleasanton, CA
If the mains supply wire is sized appropriately, the current going through the winding's is exactly the same wired for 240v vs 120v. However, if the wire or cord is undersized, this can lead to a larger voltage drop for the 120v case than for the 240v which can lead to a higher current draw for 120v (and higher motor temperature).
I now realize that what I posted may have caused some confusion so let me explain further.

There are two poles in a single speed induction motor. Each pole is a separate winding. When wired for 240v, the two winding's are fed in series so there is effectively 120v across each of the poles. When wired for 120v, the two winding's are fed in parallel with 120v across each of the winding. So in both cases, the same current is traveling through each winding and there is the same voltage across each of the winding. But because the 120v wiring is in parallel, the draw from the mains is 2x that of the 240v case.
 

JamesW

TFP Expert
Mar 2, 2011
15,592
Note hp = watts, you could say a 750 watt pump and it means the same as a 1 hp pump
The hp rating of the pump does not directly translate into how many watts it uses.

For example a 1 hp full rated Whisperflo pump will use close to 1,650 watts, which is about double what you would expect.

First, you have to look at the total hp, which is the rated hp x the service factor.

A full rated 1hp WhisperFlo has a total hp of 1.65 hp.

The total hp is the delivered hp, which is the total power used x the efficiency.

For induction pump motors, the total hp x about 1,000 will give you the total power used.

This is in contrast to a gas heater, for example, where the rated power is the total power used and the delivered power is the total power used x the efficiency.
 

cfherrman

TFP Guide
May 10, 2017
2,280
Hays, Kansas
If the impeller is only a 1 hp it will draw only 1 hp, except for efficiency

The motor can say 20 how it still will draw close to 1 hp, except for efficiency