Author Topic: How much Generator do I need for my well pump?  (Read 5344 times)

Offline txoutback

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How much Generator do I need for my well pump?
« on: January 09, 2013, 10:02:08 AM »
I am shopping for a backup generator to power my well pump. The well is about 225ft deep, but the original installer lost all his records of it.

The control box on the well-head has some technical info printed on it:


Model: CB10412

KW: .75 (750W)
AMP: 8.2
ST MAX AMP: 9.8

V: 230
HP: 1
PH: 1
HZ: 60

RPM: 3450


Based on that info, would a 6500W generator that can handle 7500W peak would work?

Thanks for your help!

Offline txoutback

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Re: How much Generator do I need for my well pump?
« Reply #1 on: January 09, 2013, 10:27:18 AM »
As a followup, I see there's 8.2A and 9.8A "ST MAX" listed.

Multiplying those by 230V gives me 1886W and 2254W respectively... is that really the requirements for my well pump? Seems so low! If its true, then I could use a 5000W Genny and bring the rest of the house into the mix.

Cautiously Optimistic...

Offline Luvmy45

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Re: How much Generator do I need for my well pump?
« Reply #2 on: January 09, 2013, 11:15:59 AM »
Assuming the ST MAX is the startup surge for the pump... you would want to size the generator to be above that so it doesn't bog down, turn off, or trip the circuit.

Your numbers look correct... but it's always best to verify, put a meter on it and see what it actually is drawing.

Offline RationalHusker

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Re: How much Generator do I need for my well pump?
« Reply #3 on: January 09, 2013, 11:26:58 AM »
Great topic.  Just tagging so I can follow.  I rent a farmhouse, and we have rural water (i.e., public supply for rural areas).  However, there is a well for livestock and garden watering.  Be nice to be able to tap that in cases of emergency.  Thanks for the thread topic.

Offline Morning Sunshine

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Re: How much Generator do I need for my well pump?
« Reply #4 on: January 09, 2013, 09:21:34 PM »
tagging for my info as well  :)

Offline GSL68028

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Re: How much Generator do I need for my well pump?
« Reply #5 on: January 10, 2013, 03:52:46 AM »
We have a 200 foot well and the electrician told me it will draw 2500watts. I got a 6500w generator and he hooked up the transfer switch to include the furnace blower fans, garage outlets and the kitchen.  The well doesn't need run the whole time and is the most draw. After showers and water gathered I can flip off the pump switch and have plenty of extra power. The well only need on a couple of times a day but it draws a LOT of juice.

d3nni5

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Re: How much Generator do I need for my well pump?
« Reply #6 on: January 10, 2013, 06:15:25 AM »


Check out this file.   Page 32 has recommended generators.   I *think* this matches up with your given specs, but I'm not an electrian.   Maybe it will help.

http://www.aggressivepump.com/CentriPro%20Motor%20Full%20MAID.pdf

If I'm reading it right, it is saying a 4KW generator.

Offline txoutback

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Re: How much Generator do I need for my well pump?
« Reply #7 on: January 10, 2013, 08:07:59 AM »
Yep, its a Centripro, so that should do the trick. Thanks for finding this, Mountain State Prepper!

Offline Tyronedeblanco

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Re: How much Generator do I need for my well pump?
« Reply #8 on: January 11, 2013, 06:29:25 AM »
glad someone brought this up.   im working on my battery bank (steven harris) and im wondering if / how many times i can power it from my battery bank once i get it all tied in correctly. 

Offline armymars

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Re: How much Generator do I need for my well pump?
« Reply #9 on: January 11, 2013, 01:58:57 PM »
   Rule of thumb is 1KW per/HP. It's the start up current rush or stall current that gets you. The electrician who put in my whole house generator would not wire in my central air because it would not handle the stall current rating of the A/C. This was a code requirement.

Offline Sarey

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Re: How much Generator do I need for my well pump?
« Reply #10 on: January 16, 2013, 09:36:16 AM »
Funny how you find just what your looking for when you need it...

Seriously I get the best idea's right here on these boards.

Offline Tyronedeblanco

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Re: How much Generator do I need for my well pump?
« Reply #11 on: January 24, 2013, 04:46:09 PM »
i love these boards!!   It's Like DIY heaven on HGH!!! You guys are the best!

Offline txoutback

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Re: How much Generator do I need for my well pump?
« Reply #12 on: January 24, 2013, 05:00:09 PM »
Tyronedeblanco, You'll need to calculate the load your well requires and the amt of time it takes to fill your pressure tank, then that will give you an idea of the amp/hours you need for your battery bank.

You'll also have to deal with whatever might be incurred from converting the batteries to 220V instead of the normal 110V...Or could you run direct DC? I dont know if the conversion from AC to DC happens at the control box above ground or deep down in there at the pump... seems the former might be a best-case.

Be sure to chime in with your findings... inquiring minds want to know!

Offline Tyronedeblanco

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Re: How much Generator do I need for my well pump?
« Reply #13 on: January 24, 2013, 05:17:14 PM »
Ya will do.  I have an expert on speed dial that is coming over to help me get this set up correctly.  I have my bank all set, just need to find the info on my pump and grab a transfer switch or interlock.