110V/220V and Pump Question


Active member
Oct 18, 2016
Long Valley, NJ
Bought a new house last August that has a pool. This is our first time owning a pool. Pool is in decent shape, and all the equipment works, but the plumbing is a functional and cosmetic mess, and the pump timer is broken. I'm pretty handy, so decided to tackle fixing everything myself.

While planning this out, I started to look at SVRS options, as our pool inspector had recommended installing one. While Googling, I found that Hayward and Pentair make pumps that are variable speed (allegedly more efficient), include a digital timer, and include SVRS. These pumps run about $1200.

When you consider an add-on SVRS is $500 and a new timer is $100, you're "only" paying $600 for a brand new pump, far simpler install, and alleged energy efficiency. BUT...

- These pumps are 220V; I'm currently wired for 110V
- These pumps are 3HP; I currently have a 1HP pump that is sufficient

So, first, my pump questions:

- Is a 3HP variable speed pump an appropriate solution to replace a 1HP single speed pump? Overkill? We don't have any water features or anything fancy; just a skimmer, sidewall suction, and two returns.
- Are these pumps really that much more energy efficient? Physics says work is work, and if I need to filter the entire pool (29K gallons) each day, it will take roughly the same electricity whether I run a 1HP pump for 10 hours, a 3HP pump for 3 hours, or a 30HP pump for 15 minutes (gross generalization, but hopefully you get what I'm hinting at).
- Any other benefits besides efficiency of having a variable speed pump?

Now, my electrical questions (I also posted these on an electrical forum):

I currently have two 20A, 110V electrical circuits run out to my pool equipment area. The circuit breakers for each of these are right on top of one another. The wiring was done with 12/3, so there is only one neutral between the two circuits. I can easily convert this to 220V by replacing the individual breakers with a 20A double pole breaker. However...I also need 110V on the equipment pad to run the vacuum.

I've attached a diagram of what I'm thinking about doing. If I have my electrical theory right, the two hot legs have 220V potential to each other, and if I connect one hot leg to neutral, it will have 110V potential to ground.

Questions are:

1. Is this legal?
2. Is this safe?
3. If I overload the 110V outlet, either with the pump on or off, will it trip the double pole breaker?
4. What happens if I am running the pump and have something plugged into the 110V outlet at the same time? Will it cause pump problems due to a lower voltage in one leg than the other?

Pool Electrical.jpg


TFP Guide
Jun 4, 2012
western NY
Technically you already have a 240 volt service out to the pool panel. The ground wire feeding this should be insulated as well. It is a bit of a grey area depending on where the panel is located but, everything going out of the pool panel needs the insulated ground. The two breakers on top of one another are technically ok as long as the feed breaker from the main panel is a common trip two pole breaker. You technically already have 240 out there if you measure 240 between the two breakers in the pool panel. If you want to run a 240 circuit and a 120 circuit they will need to be on separate breakers. You can, if there is room, add a double pole breaker into the pool panel if needed.
Edit: The next post brings up a good question. Is there a sub panel(pool panel) at the pool or just two 120 circuits running out there?


Bronze Supporter
TFP Guide
Jul 24, 2015
Central Valley CA
Assuming a ground is present just not documented to connect it the way you want and be legal / safe you would need to install a sub panel at the pad with separate breakers for the 220 and the 110. That is exactly the way my builder did mine. When installing a sub panel the neutral is not bonded to the ground the only place you do that is at the main panel, most panels have a green screw on the neutral bus bar runs down to the case bonding it, just remove that screw and you are good to go.

VS pumps are for sure the most efficient when it comes to power consumption. When it comes to saving money often a 2 speed motor replacement on an existing pump may be more economical because of the lower purchase price. If your equipment is old and you are staring fresh I would go with the VS.

I will let someone else comment on the 3HP pump for sure not needed but I don't know if there is a reason it would cause a problem. My gut tells me not a problem because you can just run lower RPM thus lower GPM

As to the savings to give you an idea if I had a single speed pump I would have to run aprox 1.6 hours to filter the same amount of water I do with my VS at 1100 RPM in 5 hours. The single speed per day would use 4.8 kwh if your electrical rate is $0.18 per hour that comes to $0.86 per day. My VS pump at 6 hrs per day would use 0.75 kwh x $0.18 = $0.14 per day.

BTW you don't need to filter the whole pool every day more on that in Pool School in how to.


LifeTime Supporter
Mar 29, 2008
Los Angeles, Ca
FWIW, Pentair and Hayward both make 115V variable speed pumps.
Lower HP, but sound like they would be fine for your pool.
I think the Pentair can run off of either 115 or 220, but has less power at 220.

Our electric company provides a rebate for installing a variable speed pool pump, so I just had a Hayward installed the other day.
At low speed, thing is so quiet, and uses very little power.