New Irrigation Pump Electrical Question

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Old 02-14-15, 11:08 AM
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New Irrigation Pump Electrical Question

Hello,

I have what I think are three easy questions that I would very much appreciate some advice on. I am installing a new irrigation pump in my garage. The pump is a 1.5 hp Goulds pump. Standard stuff. I am planning to run a new electrical service so that my electrician can hardwire the pump. The pump will run on 230v. According to the installation instructions that came with the pump, the full load amps is 10 and requires a standard circuit breaker of 35 amps. My electrician says that I can utilize a currently unused 40 amp circuit breaker in my panel. I think this is probably ok but thought I would double check.

The pump installation instructions also say that for distances of less than 100 feet (my situation) from the electrical service entrance to the motor, 14 AWG wiring is sufficient. I'm a little uncomfortable with that gauge of wire. I have an electrical book that says 230v, 40 amp service requires 8 AWG wire. Will I be safe if I use 12 or 10 AWG wire for this? My guess is that because the full load amps draw is relatively low (compared to the start up draw), the manufacturer doesn't believe a heavier gauge wire is needed, but again, I thought I would see what others think about this situation.

Third question. My understanding is that even for an irrigation pump (where water is present), if it is hardwire (i.e., no plug), you don't need a GFCI breaker, but a standard breaker. Is that correct?

Thank you to everyone for the advice. It is much appreciated.
 
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Old 02-14-15, 11:56 AM
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I am planning to run a new electrical service so that my electrician can hardwire the pump.
If this is a detached garage and already has electrical you can't run another feed.
 
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Old 02-14-15, 12:18 PM
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Hi Ray

I'm sorry, maybe I used the wrong term in my original post. The garage is attached. The sub panel is in the basement and the basement shares a wall with the garage, so the plan is to run the wire from the subpanel (which has open multiple open slots and one unused 40 amp breaker) along the ceiling joists, to the shared wall, through the wall and into the garage. I have already had this done once (by a licensed electrician and then inspected) to add two 115v outlets for shop tools, so I know that a similar setup is ok in my town. Does that help?

Thank you!
 

Last edited by njtl1983; 02-14-15 at 12:46 PM.
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Old 02-14-15, 02:51 PM
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Motors have special rules in regards to wire sizing and over current protection. 40 amps seams a bit excessive to me, but I would need the name plate info to figure it out.

You do not need to GFCI protect the motor. Even 240 volt receptacles (cord ans plug) are not required to be GFCI protected, even in the presence of water.
 
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Old 02-14-15, 06:22 PM
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I think a 35 amp breakers is excessive for a simple 1 1/2 HP motor. The online motor data calculator I like agrees with the #14 wire, but says use a 20 amp breaker. At 115 volts it would be a 40 amp breaker. Are you sure you read the breaker size for 230 volts?

Single Phase Motor Data
 
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Old 02-14-15, 06:33 PM
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40 amps (or 35, per the instructions) seemed like overkill to me, though I hesitate to contradict the instructions. Here is a link to the online version of the instructions that came with the pump. Page 6 is the electrical specs. My pump is the GT15.
 
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Old 02-14-15, 06:52 PM
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I find manufactures recommendations are sometimes hard to swallow when they fly in the face of common sense.

I would recommend running #12 wiring to the pump. #14 is sufficient but you will have less voltage drop and easier motor starting on #12.

As far as a breaker..... 30A maximum....... although I would try it on a two pole 20A first. If it trips.... change for a 30A.
 
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Old 02-14-15, 07:02 PM
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Page 6 is the electrical specs. My pump is the GT15.
Look again. The thermal circuit breaker you'll be using is considered a time delay device sort of like a dual element fuse. The chart calls for a 20 amp delay breaker.
 
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Old 02-15-15, 08:56 AM
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@joe

I read that as you could use either a standard circuit breaker OR a delay type (I thought this referred to the special use breakers that are common in Europe) given that all circuit breakers have some delay built in. Is that not correct?
 

Last edited by njtl1983; 02-15-15 at 09:14 AM.
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Old 02-15-15, 06:57 PM
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The delay built in to the breakers available to you for a typical loadcenter is all you need. Use a 20 amp breaker. I doubt you'll have any problem.
 
 

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